Tejon #7 - 1990 Crown Supercoach

[Tejon7]

Hello everyone! I've been lurking here for a few months. I'm getting started on my bus build, so I thought this would be a good time to start posting. Hopefully, I'll keep this build thread updated so that others can learn from my mistakes and so that I can come back years from now when I'm scratching my head, wondering "What the heck was I THINKING?".

Our bus is a beautiful beast. It's a 1990 Crown Supercoach with a Detroit 6-71T paired with an Eaton Fuller Roadranger 10 speed. It was in service for the El Tejon Unified School District, a mountain community above Bakersfield, CA, up until about 2016. It has 146k miles and ~9000 hours on the motor (BTW, does anybody know if these numbers jibe with each other??). She drives like a dream, but I drive like an idiot. That last part got a bit better over the 1200 miles that I had to drive her home, from Bakersfield, CA to Missoula, MT

I bought 'ol Tejon #7 from a fantastic guy who bought her at auction. I won't share this gentleman's info on the internet, but he was possibly the best seller I could have asked for. He jumped through multiple hoops to make sure the bus was in tip-top condition before selling it to me. He put in brand new 8D batteries, a new turbo, had three injectors re-conditioned, and had various other tune-ups done. I was soooo fortunate to have found this fella! I think he's a forum member here - if you're reading this, I can't thank you enough!

I have a general plan for most of the conversion, but I also have many, many questions. Hopefully all you knowledgeable folks will share your wisdom with me as I go along! Especially you Crown specialists - there's a couple beautiful Crown builds here that I plan to extensively copy from (you know who you are! Thanks for sharing!).

I hope to update this page frequently as I go, but no promises. So far I have the seats out and am working on removing the aluminum ceiling panels and fiberglass insulation in preparation for spray foam.

Wish me luck, as this will be a long project!

[PNW_Steve]

Nice looking bus!!

When I win the lotto I am gonna buy me a Crown with a Detroit 2 stroke and a 10 speed

I don't think that there is a more beautiful example of a school bus to be found than the Crown.

[Native]

Congratulations. Looks like you have a nice one.

[Tejon7]

Thanks guys. We're certainly excited about it.

Steve - I remember reading in an older thread that your dream bus would be a Crown with a Detroit. That actually helped me take the plunge and no regrets so far. So thanks for that!

As for being a millionaire to get one of these... I was originally hoping for a $3500 40' pusher off of GovDeals or Public Surplus, but when I stumbled into this Crown with an asking price of $7500, I found it easy to justify doubling my budget. I feel like that's an absolutely phenomenal price for this work of art, especially with all the mechanic-ing that was done to it before I got it.

So a little more about the bus and our intentions:

It's a mountain bus, with jake brake, auto tire chains, heated mirrors, and a cushy El Dorado air ride seat. Being in Montana, all those little add-ons may be useful.

My wife and I lived for a few summers in an '84 International S1700 about ten years ago. We had done a very rudimentary conversion on that bus, but it was some of the best times of our lives. We've acted like grown-ups for a decade, and now we're itching to get back to a nomadic lifestyle. We hope to move into Tejon #7 full-time in a year or two.

Current plan is to do a semi-fancy conversion. To me, that means trying to do everything right, but leaning toward re-used stuff and sale shopping wherever possible. We're not on an unlimited budget. Also, we like that it's a bus, and we're going to try to keep it looking like one as much as the law allows. That means keeping the stock windows (which are fantastic, but inefficient), and possible re-using the aluminum ceiling after insulating.

Like everyone else here, our plans will evolve, so don't give me a hard time if I completely change my tune in a few months!

-Eric

[Crown_Guy]

You asked for it. So here goes. Make sure you know and Really understand about the use of the proper oil. DD 2-strokes MUST only use CF2 rated Mineral (not synthetic) based with the lowest ash content rating available. Generally and historically speaking the only one in wide use is Delo 100(mineral) CF2 straight 40wt. Delo 400 is a synthetic based oil and NOT recommended by Detroit Diesel. There are a few other brands out there but the key is the CF2 lowest ash rating mineral oil. If it isn't CF2 rated equivalent then don't use it

In the winter you may need and can use straight 30wt for those really cold conditions. It may be better though to have auxiliary heating systems available where the engine, oil, and coolant can be heated up before starting, in order to allow the use of the 40wt which is preferred. Under no circumstances should any multi-grade oil ever be used. To make sure of having the correct oil with you at all times, since you will be having to add as you drive, that's the charm of the 2-strokes, make sure you always carry a case of Delo 100 or one of the few equivalents with you always. Be prepared because you won't be able to find it on the road, it's unobtanium.

Also a spare set of all filters and belts is an extremely good idea. The oil and fuel filters aren't hard to find, neither is the water conditioner whatever you may have, but Senor Murphy always finds a way to put you down hard somewhere remote where you can't find or reach a parts store at o'dark thirty. Both sets of belts are also pretty hard to find since they are so long, and worth their weight in gold to have on-board against the day you need to replace one/them. Easy to fix but hard to find.

I'll assume it has standard rear end gearing and probably a 10spd where 10th gear is a direct drive 1:1 output ratio, you'll know it's a direct drive since 5th/10th gears are located DOWN and to the right in the shift pattern. In case it's an overdrive the 5/10 gears will be UP and to the right. With the oh so standard school bus 4:11 rear end ratio the top road speed in direct 1:1 high gear (5-spd or 10spd trans) will max out at around barely 63mph at almost 2300rpm, if it goes that high. Some are turned down to a sedate 2150rpm for typical fleet operations and better fuel mileage, and slower road speed, 60....maybe.

Whatever you now have rest assured that it can be fairly easily improved to the point that you can make it a true highway cruiser and maintain 75mph with no effort all day long and it won't be breathing hard, not with the turbo, and max out at 80 easily. You're definitely going to be in the market for higher road speed living where you do once you get the hang of driving it under your belt. When everybody is passing you on the Interstate just remember you too can go that fast,....if you want to. It's pretty easy really. Not free. But not too much $$ either

I did this for a lady who bought a nice 35ft Crown, a tad shorter than your 38ftr, but exactly the same in performance. It also had a 6-71T and Jakes with an automatic transmission. We upped her rear end to a 3:70 and where it now did a measured 80mph and cruised at 75 easily without having to thrash it or keep buried in the throttle, at around 2100rpm which is good.

Living in Boulder and planning to drive long distances on the Interstates made sense for her. The high plains altitude had no impact on it's performance, unlike all non-turbo'd Detroits which fall off rapidly with increasing altitude. The turbo makes up for the thinning air and keeps the performance at sea level horsepower ratings. You may also be considering something similar.

If all is well mechanically with the Crown they will cruise at these highway speeds with ease and you'll feel totally comfortable and in control. She had never driven a bus of any kind and was shocked to look down when we left L.A. at how fast she was going and that it was not even noticeable to her. These attributes are why I always say they are like sports cars on the road where you are in intimate contact with the vehicle and the road with no strain or effort. It's the biggest part of the joy of ownership, as I suspect you're just now finding out about.

A couple things to know about in case you've never had the chance to drive a DD 2-stroke engine. As an aside while you struggle to learn how to shift it, which I'm sure you're dealing with, and know that it will get better with practice and experience, you should always make an effort to NEVER lug the engine down below 1600 rpm while trying to pull full throttle. This means that as you blow the shifts and get all lost and screwed up try real hard not to just power out by lugging it until it starts to pull better. The power range for that engine is from 1600 to 2300 and if it goes below 1600 make sure you downshift it, if you can.....This too will get better and easier with practice.

There is real danger to the engine by lugging it and keeping the rpms at the low end of the power range, even if it seems to be pulling OK. The turbo lulls you into thinking that all is well and you can keep the rpms low, but that's not true. Low rpms with full throttle application will cause the coolant temp to rise as well as stress the bearings and cylinder head and other key things. Downshift and keep the engine rpms between 1600 and 2300 and you'll never hurt the engine. Running it above 1800 is best. This moves coolant to keep it cool and doesn't stress the engine. You'll also find with experience that it has a sweet spot where it likes to settle down at about 1900 rpm when you take your attention off it. This is a clue to where it really likes to be running. This is a good thing and you should be trying to run it here on the road. You'll notice you are lifting the throttle slightly in this sweet spot which will give better mileage and efficient engine operation. You can't always do that if you need the road speed so don't despair, You can run the engine all day long if needed right up on the governor at full engine rpm with no damage or long term issues, and most are set up to be run like that in order to get any kind of highway speed. That's what they had to do as school buses. 55 mph at almost full governed speed. Do it with a clear conscience, it won't hurt a thing, and the engines are made to do this and be run like this. That's what you have now. Just know you can make improvements with lots of room for speed and economy.

When pulling a hill or grade and it doesn't feel like it wants to pick up the next gear, by all means downshift to where you can go up the hill at 2200 or so in that gear, that's the one you need. This is how you drive a 2-stroke. TWO RULES. NEVER get it hot, and Don't lug it down. Lugging will lead to getting it hot and very bad things flow from that.

Keep the rpms up and learn to drive it close to the governed engine speed at all times. That means that when you are accelerating and up-shifting you MUST take it up until it bumps into the governor (actually just a tad before) and then make the shift to the next higher gear. That way you'll end up in the higher gear about 300 rpms lower while still in the power range about 1700 or 1800 or so. The key is to learn to drive the thing like you're mad at it, and I mean it, they need the high rpms and full throttle while shifting to keep coolant flowing and the power keeps the rings seated and not blowing out oil. FULL throttle when shifting and run it up to the governor before shifting. Do all this and you'll get the most out of it and a long and happy life for the engine.

You'll notice how fast the rpms drop between shifts going up and it seems like you just don't have enough time to do the double clutching thing...Well guess what. You don't have time, and that's why most every driver with experience will learn eventually to drive without using the clutch. As long as this is done carefully enough (while learning) and you don't just try cramming it into gear before it's ready you won't hurt anything. Your goal should be to learn how to float the gears out and then in as you change the engine speed with the throttle. Gently ease into the gear and the transmission will oblige by not being ready to take it until the speed match. You can feel how square the gears feel (shift collars actually) and with a very narrow mechanical gateway to allow for the gears to engage. As long as you don't force things it will become second nature and very natural and smooth for you. Try to gain enough finesse so that you can shift so smooth nobody even feels it on the bus. A cup of water on the dash is a good indicator. If you can learn to do this you will have become a proper professional grade Road Ranger driver and better than most Commercial Drivers today. A real accomplishment, take pride in improving your skills, it's guaranteed to increase your enjoyment of and appreciate the Crown even more. They are truly a Drivers bus and once mastered you will never find their equals again.

And don't forget the proper Delo 100 40wt oil.

If driven as they should be, which is becoming a lost art the Detroit 2-strokes are exceedingly reliable and hard to hurt. That was one reason they were so popular at one time. We all were taught and learned the correct driving techniques and managed to get enormous miles out of them. 4-500K miles was not unusual with routine maintenance and proper driver care. I like to say that a Crown will always get you home and the DD is a big part of that.

I've always loved the 2-strokes and with a 10spd it's a divine experience. That's what I learned to drive in all those years ago. I also now have a second Crown with a 6-71T and 10spd just like yours. Now I can really enjoy the fantastic 2-stroke sound whenever I want to, and I fully intend to change the rear-end for speed, plus it'll need Jakes eventually, but the basics are already there and it's just way too much fun to drive. I love it. So now I have one of each, the monster Cummins, and a sporty 35ft with a 6-71T 10spd, what could be better than that.

And welcome to the exclusive Crown owners club. It's special, as you'll soon really find out. It's also money well spent. It'll last longer than you and can be given to your kids. Plus there won't be any more made so you do the math. Exceedingly long life and dwindling supply. Does that suggest something to you. A lifetime investment and enjoyment plus going up in value for sure. What's not to love. It's already happening.

Enjoy it and contact me direct if you feel the need and have questions.

mikemcc2k@yahoo.com

[Placeholder Bus Name]

Reading all of this posts makes me want a Crown. Dang that's sweet!

[Danjo]

I love that your bus came with a great name

[Tejon7]

Originally Posted by Crown_Guy

You asked for it. So here goes...

This entire reply is one big fantastic chunk of knowledge. Thank you for taking the time to share all of this! I feel like I should boil this down into bullet points and make it into my pre-drive checklist.

Originally Posted by Crown_Guy

...Delo 100(mineral) CF2 straight 40wt.

I hear this repeated time and time again, so I'll heed the advice of those with more experience. You'll never catch me without a few gallons of Delo 100! To keep things simple, I think I'll try to stick with 40wt (at least at first) and use aux heating systems as you suggested when it's chilly out. My bus has a coolant heater installed, but I may also build some kind of reflectix enclosure and a Mr Buddy that I can put under the oil pan.

I didn't realize that the belts are a hard-to-find size. Thanks for that tip! I'll definitely track some down before travelling. Waiting days for a simple belt change would be frustrating.

Originally Posted by Crown_Guy

I'll assume it has standard rear end gearing and probably a 10spd where 10th gear is a direct drive 1:1 output ratio...

Correct assumption. 10th is 1:1. I'm not sure how to verify the diff ratio, but it sounds like 4:11 is probably right as well, since the speed/rpm you combo you mentioned is very close to what I experience. My tachometer is fritzy, so I'm never sure about that, but it governs out in 10th speed at about 67 mph. I'm not 100% sure the speedo is correct, or that the governor is set properly. I'm slowly troubleshooting my tach problems, and once that's fixed some of this might be a bit easier to nail down.

I'll eventually start a new thread about my tach woes, but for this conversation here's the gist: Tach was bouncing around, so I looked for loose wires. Found the connection at the alternator was just barely hanging on, so tightened it down - bingo! Rock solid for a few hours/hundred miles. Then intermittently accurate mixed with ~1000 rpm too high. Now always ~1000 rpm too high. I eventually started ignoring it, so I'm not sure if it stays ~1000 too high, or if the error varies with engine speed. Ok, back on track...

It's good to know that increased highway speed is attainable. For now, I'm happy in the slow lane. For me, converting into a usable living space will take precedence in the short term (haha, 'short' meaning several years). Once it's livable, I would love to change to a higher diff ratio.

Originally Posted by Crown_Guy

A couple things to know about in case you've never had the chance to drive a DD 2-stroke engine. As an aside while you struggle to learn how to shift it, which I'm sure you're dealing with, and know that it will get better with practice and experience, you should always make an effort to NEVER lug the engine...

Thanks to you and others here who have shared this. I have to admit, I DID lug the engine for a few brief moments at first. Having lurked around this site for a while and having seen similar warnings for you and others, I knew that lugging DD engines was no bueno. I'm still no pro, but I'm now much better at finding the gear I want, so lugging should be a thing of the past!

As you mentioned, practice IS making shifting easier.

Originally Posted by Crown_Guy

The key is to learn to drive the thing like you're mad at it, and I mean it...

There is a TON of important info in your reply for new DD/10 speed drivers like myself. I think the above quote is the most helpful for me. Coming from my experience driving a regular 'ol 5 speed automobile, I hear that DD engine screaming and I think I'm doing some long-term damage. With reassurance like this from experienced DD drivers, it becomes easier to really give'er as my Canadian friends say. Once you're up around the governed rpms, shifting becomes easy. I found during my 1200 mile journey home that, as you suggest, float shifting is much easier than double-clutching. The shifter just falls into place when the rpms are right. I was lucky enough to have a well-seasoned driver along for some training when I bought the bus. He gave very similar advice as you - be patient, be gentle on the stick, get the rpms right, and don't bother with the clutch unless starting from a stop light.

Many thanks for all this information! I hope that future Crown/Detroit/Roadranger newbs like myself find your post and learn from it. I know I'll be referencing this info regularly until it's burned into my brain!

-Eric

[Tejon7]

Originally Posted by Danjo

I love that your bus came with a great name

I know! I didn't really care about a name, but one just fell in my lap and I love it! For Español-deficient folks like myself, Google translate says that 'Tejon'=Badger=Bada$$ name for a bus!

[Tejon7]

This is my first progress update, so I'm going to try to set a theme and stick with it. My goal is to get out some basic, need-to-know info at the top of these updates, then fill in with details and pics lower down. I'm guilty of 'skimming' through some of the longer build threads, so hopefully this format will help similarly lazy readers find information that's helpful to them. Here it goes...

Progress: Seats, ceiling panels, and fiberglass insulation removed
Time: ~20 hours
Difficulty: Not technically demanding, but pretty sucky at times
Useful Tools: Impact driver, air compressor, air hammer, wire brush, PPE

Seat removal
This was super easy. I was expecting this to be tough, since my last bus had the seats bolted through the floor ('84 International S1700). That was definitely a two-person job, where one person crawled underneath to hold the super rusty spinning nut, while the other used a ratchet (and sometimes breaker bar) to loosen the bolt. I didn't have two people, so that really sucked. The seats in this Crown, on the other hand, were a joy to remove. I think they were all out in under an hour. Each seat had two bolts that threaded directly into the chair rail. Another two bolts secured the aisle-side feet by threading through the plywood floor and into a steel plate that runs along the length of the bus at either side of the aisle. With an impact driver, it took about 30 seconds to remove each seat. YESSS!!

It took much longer to separate the seating components for recycling. Still very easy, but a bit time consuming. And gross. Kids are disgusting and I'm embarrassed to have ever been one. So much gum! I thought gum-chewing kids was a Hollywood stereotype, but it's been proven true on this bus!

Anyway, back to the story: I kept 4 seats (two port, two stbd), then drove Tejon over to the recycling place and dropped off ~900 lbs of steel seat frames. I got $10 for my efforts. Then it was off to the dump, where I dropped off another 500 lbs of seat stuffing and vinyl.

Driving through rush hour traffic and navigating tight roundabouts for the first time was exhilarating! I got tons of attention - mostly positive. The Prius behind me at a stoplight wasn't pleased, but I swear I wasn't trying to roll coal - it just does that sometimes!

Ceiling panel removal
There were around 2200 rivets to remove before I could get the ceiling panels out. I feel fortunate, in that Crown used 3/16 steel/aluminum rivets in my ceiling (except for a few... we'll get to that later). The steel mandrel meant that drilling them out would have been a pain, but using an air hammer and the center punch/chisel method was fairly painless. The mandrel punched out pretty easily. Then a sharp chisel sliced off the aluminum head nicely. One thing I hadn't seen mentioned much but that helped me immensely - keep the chisel tip sharp. After initially putting a bevel on the air chisel with a bench grinder, I found that I needed to re-sharpen it with a file after every 100 or so rivets. After 100 rivets, it was noticeably harder to slice off the rivet heads.

Our current plan is to re-use the aluminum ceiling skin after spray-foam insulating. It's light weight, the perfect size, fire-resistant, *free*, and we like the look (painted a different color, of course). I dinged it up a bit here and there, but overall it's still presentable. One place I messed it up a bit, though, is in the rear curved section. There are two strings of 1/4" rivets with 1/2" heads back there (see pic). It turns out they're just holding two pieces of aluminum sheet together and aren't into a steel structural member as I'd assumed. So future Crown converters - don't remove these larger rivets! Doing so just makes more work for you and unnecessarily mangles the aluminum sheet.


Fiberglass insulation removal
I'm so glad we decided to remove the old insulation. The ceiling cavity was completely full with very few gaps, so the folks at Crown did a good job. But fiberglass is still crappy insulation compared to spray foam. And there was a good deal of black mold toward the back of the bus. I can't find any noticeable leaks, so maybe it's just that all the mouth-breather kids sat at the back?? I'll go through and super-seal everything just in case, but I'm glad we caught this problem and fixed it.


I removed the wiring chases pretty early on in the ceiling panel removal process and found black mold. After that, I played it safe and wore a respirator for the rest of the air hammer and insulation removal work. Once the ceiling panels were out and I really started into the insulation, I found that coveralls and a face shield were much better protection than the t-shirt and safety glasses that I wore the first afternoon


Crown used a black adhesive that looks like rhino-lining on the interior ceiling. I assume this was partially sealing, partially sound-proofing, and partially adhesive. The insulation definitely stuck to it, so the only way to get it mostly removed was to scrub with a wire brush. I tried with a wire wheel on my drill, but the wire brush was easier. This scrubbing caused the air to fill up with millions of tiny fiberglass particles, so proper PPE was essential. After scrubbing out the stuck-on insulation, I used a pump sprayer to spray a diluted bleach solution over the entire ceiling area.

[ol trunt]

Nice wright-up and quality work. Glad to see it.
Jack

[Tejon7]

Progress: Window cavities cleaned out, backup cam installed, strobe removed
Time: ~6 hours for the windows, ~4 hours for camera, ~4 hours for strobe delete
Difficulty: Fairly easy, but the windows were gross
Useful Tools: Wonder bar, thin strip of aluminum, lighted mechanical pickup tool (Google that and you’ll know)

Window cavities
I’ll get this out of the way right at the beginning: if you’re going to remove you Crown’s windows for any reason, do that first before cleaning out the pocket that they slide into. It would be easier with the window removed. If you’re hoping to leave your windows in place like me, then read on…

Crown busses have a very clever dry wall design where the windows retract into a pocket between the interior and exterior panels. This way, any rain water or condensation on the window will run through the wall cavity and out of the “gutter” at the bottom, like this:


From an engineering and aesthetic standpoint, this window layout is fantastic. But before the design team opened the champagne and started high-fiving each other, I feel like they should have asked for a fifth-grade teacher’s opinion. I’m sure a teacher would have sighed, shook their head, and instantly seen what was going to happen to those poor, beautiful windows. On my bus, the window cavities were filled with a prodigious amount of s**t. Markers, pencils, erasers, rulers, plastic Dracula teeth, cardboard Valentine’s, batteries, and an unholy amount of junk food wrappers. The picture below is the junk that came out of one window:


I could make many observations about what kids actually eat or discard on the bus, so feel free to PM me if you’re a head-scratching parent or junk-food company executive. For the rest of you, I’ll just share my observations about Nutri-Grain bars. These things should not be consumed by humans, and kids apparently know it. Scores of these things were jammed into the windows unopened or with one bite out of them. There they sat for 10, 20, or 30 years. Yet every single one of them came out smelling exactly like it was fresh baked from the factory. Even though some of them came out soggy and visibly unrecognizable, I could instantly identify them by their fresh Nutri-Grain smell. I can’t even fathom the amount a preservatives necessary for that. Unless you want to mummify yourself from the inside, steer clear of these puppies!

The task of removing all this crud took me about 6 hours. In-between being grossed out, I was actually kinda fascinated with what treasure I’d find next. I got into a groove and lost track of time, so it may have taken 8 or more hours. I found that the best technique was to use a flat pry bar (eg Stanley Wonder Bar) to gently open up the bottom of the gutter, then use a thin piece of aluminum to scrape back and forth and pry out junk. Conveniently, the piece of aluminum I used fell out of the first window cavity that I cleaned out. Occasionally, larger items would need to be pulled out with needle nose pliers or carefully removed from the top with a ‘lighted mechanical pickup tool’ (Google that and you’ll know exactly what I mean).


Backup camera
I have a local insulation company coming to do spray foam in about three weeks, so I’m hoping to finish most of the roof penetrations before they get here. I wanted a camera mounted fairly high on the rear end, so now seemed like a good time to get that installed. I went with a cheap model from Amazon, the DVKNM. It came with a long enough video cable and claims to be ‘Antiseptic’. An antiseptic camera for $80, you say?! What a steal!!
https://www.amazon.com/1024X600-Wate.../dp/B07HFWPRPG

Installing this was pretty easy, even though the instructions were nearly useless. Most of the time on this project was simply trying to figure out the rats nest of wiring under my dash. Crown did a fantastic job of organizing wires, but there have been a few additions and subtractions since it left the factory that have... confused things a bit.

The wiring harness has a red, black, and blue wire. Red for 12v power supply, black for ground, and I believe blue can hook to your backup light to switch to a different camera when you shift into reverse. I’ll probably add a second camera later, but for now I only used the red and black wires. I hooked these into the old strobe light switch, since I’ll be removing the strobe.

The camera is pretty low end, but I think it’ll work. Because of my Crown’s curvy rear end, the camera’s high mounting point means that I can’t see directly down to the bumper. Someday I’ll add a bumper-level camera and wire it to the reverse gear for backing into tight spots. For now, though, this will be fine.

Stobe delete
My strobe was leaking and totally unnecessary, so I removed it. That took 2 minutes. Covering the hole with aluminum took a couple hours.
I’ll be adding four hatches to my undercarriage at some point (three Stbd and one Port), so I decided to cut out one of the hatches now and use the resulting aluminum chunk to patch the strobe hole. Cutting out that hatch made me very nervous, but it turned out alright. This is the port side hatch area, which is directly across from one of the proposed stbd hatches. I’ll eventually have a 2’x2’x7.5’ storage area here behind the front wheels:


After much reading here, I couldn’t decide between Dynatron and Sikaflex for sealing around patches. I found Sikaflex at a cheaper price, and it seems to do the job. I went a little crazy with it and it’s a bit messier than I’d hoped, but you all are the only ones who will see it, so who cares? The rivets are ¼ closed end aluminum with steel mandrel. It’s hard to tell, but I’m pretty sure that’s similar to what Crown used on the whole roof.

[ol trunt]

I am a Sikaflex(220+) fan I used it to install my windshield, metal window blank outs, overlaying body seams and as sealing material for where wiring comes out of the bus body. It's been about ten years now and no failures.

Sikaflex cleans up easily with paint thinner (mineral spirits) when fresh but is tough to remove once cured. It stays flexible and accepts all types of paint.

Nice report on your high quality work.
Jack

[Tejon7]

Originally Posted by ol trunt

I am a Sikaflex(220+) fan I used it to install my windshield, metal window blank outs, overlaying body seams and as sealing material for where wiring comes out of the bus body. It's been about ten years now and no failures.

Sikaflex cleans up easily with paint thinner (mineral spirits) when fresh but is tough to remove once cured. It stays flexible and accepts all types of paint.

Nice report on your high quality work.
Jack

Thanks Jack. I remember reading on another thread that you like Sikaflex, so I decided ty give it a try. So far so good. I also used it to seal the backup camera wire entry point, and it made a really nice, flexible plug. I'll pick up some mineral spirits for the next time I use it.

Thanks to you and all the others who have shared info here. I put an estimate of my work hours for each completed task, but that doesn't take into account all the hours of soaking up knowledge from folks on this site.

[Tejon7]

Progress: Rear heater out
Time: 4 hours
Difficulty: Easy??
Useful Tools: Sawzall

Ok, I know... 4 hours is way too long for such a simple task. I was overthinking it. In the end, the sawzall came out and progress was made. My problem was trying to take apart all of the iron pipe fittings that were plumbed down through the bus's floor. I wasted an hour with various wrenches and cheater bars trying to neatly take these apart so I could slip them through the floor and remove them. Then I had a coffee break, came to my senses, and cut the damn things out 5 minutes later.

Most of the remaining 3 hours involved removing the rear access hatch (a couple stripped screws holding it down), cleaning 30 years of accumulated dirt off the fuel tank, and disposing of the coolant.

I still don't know much about my coolant system, but it looks like the heaters and the air filter box tie into two long steel pipes that run the length of the bus, forming a loop. My assumption is that closing the loop at the rear of the bus will keep everything functioning as normal. Here's a picture of what I did, as seen through the rear access hatch:

That's an empty can of chicken zip-tied to the heater hose in the 'after' pic. I failed to consider that the heater hose couldn't handle a tight bend radius. To keep it from kinking, I came up with this ugly chicken can fix. It doesn't kink any more, but there's definitely going to be a reduction in coolant flow here. Is this bodged-together MacGyver mess going to work? If not, what's the best solution here?

Also, I probably lost about 1-2 pints of coolant from the main loop during this process. I assume that means there's some air in the system now. How big of an issue is this? I think the coolant was replaced not too long ago, so I'm not planning a flush in the immediate future. Can I just start it with the radiator cap off or something? If you can't tell, I'm far from confident in my radiator/coolant system knowledge.

[Tejon7]

A real update is in the works, but in the mean time, here are some clarifications of my pasts posts with the benefit of hindsight:

Post #12, regarding cleaning out the window cavities:

Window cavities
I’ll get this out of the way right at the beginning: if you’re going to remove you Crown’s windows for any reason, do that first before cleaning out the pocket that they slide into. It would be easier with the window removed. If you’re hoping to leave your windows in place like me, then read on…

Since writing this, I've actually removed one of the windows to fiddle with it. It was surprisingly easy. I would now strongly suggest that anybody needing to clean junk out of their Crown windows should take out the glass and sliders first, then remove large items from above (instead of from below like I did).

Post # 15, coolant system confusion:

I still don't know much about my coolant system, but it looks like the heaters and the air filter box tie into two long steel pipes that run the length of the bus, forming a loop.

This is still true, I don't know much about my coolant system. But I know a little more than I did two months ago. First off, I was confused by a coolant line that seemed to run through the air filter box. It turns out there's a 120v coolant heater mounted under the air filter for cold starts.
Next, my childish chicken-can solution that I detailed in post 15 may work, but I now know that the rear 15' of steel piping is not needed, so I may cut that all out at some point and close the coolant loop closer to the engine bay.

That's it for now. More soon.

[Crown_Guy]

Just run it. There probably isn't any air in the system. Even if there is some air it will get flushed out eventually as you run it at high speed on the road. As a rule the system isn't that sensitive to air locks, but it does happen and I've experienced it with a system fully drained and filled. There's a fitting near the water pump on the top of the engine (under the floor hatch) to bleed air out, as well as another bleed valve on the front heater/defroster core in the dash area. The symptom is a spiking water temp gauge while driving along, to over 200+ degrees which will really get your attention. Pulling over and running the engine real fast with no load (or heat injection) will usually move the coolant fast enough to purge the air bubble and get it all cleared out. The temp will drop fast as the coolant contacts the probe and then you know you're all set. The little that you dribbled out is nothing compared the 30+ gallons in the total system. When you get air into the defroster core and those lines higher than the engine water pump location is when it gets to be a problem, thus the bleed valves, otherwise it's a pretty resilient system and will correct for minor air incursions or loss of coolant.

As with most things simply driving it keeps everything working as it should and generates little to no problems. They need to be driven regularly.

I'm curious about that coolant heater, does it have a pump also to circulate it or is it just adding heat to HELP warm up the engine. As maybe you don't know a diesel engine doesn't produce much excess heat for warming people or even the engine itself until it gets under a load and driving down the road. A 6-71 at idle won't get above maybe 120 degrees if you're lucky. The heaters will only blow very slightly warm air, not enough to really warm you up though. And I've spent many days on charter trips in the mountains waiting for my group and freezing as the engine never gets warm at all. You may only have the heater to help warm the coolant and get the engine to operating temp sooner. It's a mountain bus after-all. But it needs to be plugged in to 110v so I figure they used the heater while the bus was warming up in the garage/yard before leaving in the morning for it's runs. I know the drivers appreciated that since it takes more than 20 minutes of driving before it's hot enough to put out any heat to warm the interior, or the windshield defroster, or the driver.

If you have or can add a circulating pump you will have a really nice beginnings for a hydronic heating system. An additional fueled water heater of some kind will allow you to heat the engine and interior with hot water and offers another source for heat when needed. I want to do something like this for mine and make use of all the sources of heat being generated for as many uses as I can. It's good for the engine to warm it or even pre-warm it before starting if manageable.

A turbo'd 6-71 with it's lower compression ratio is much harder to start when really cold. In your area that's going to show itself real fast. Ether/starting fluid, or pre-warming the engine/coolant/oil is almost a pre-requisite for even starting at all. Consider keeping the heater element and adding a circulating pump to it so you can pre-warm the engine for those really cold morning starts.

There are actually two coolant system thermostats. They are both located in the large metal casting near the governor and up close to the floor on the drivers side. The two thermostats are each in a separate water circuit and set for different temperatures. One circuit is for the engine and interior heater cores and is set to heat the engine and heaters first. When it gets hot enough the thermostat opens and lets in coolant from the radiator loop and starts circulating that coolant loop. As the temp rises the second thermostat opens and modulates the temperature to use the radiator to keep the whole system cool and rejecting the waste so as not to overheat the engine as it works hard.

A very sophisticated and well thought out system that warms the engine and passenger areas first and then uses the radiator to reject the waste heat.

[Tejon7]

Progress: Flashers legalized and Insulation Sprayed
Time: ~4 hours to sort out flasher lights, ~36 hours for spray foam
Difficulty: Lights were a fun and easy project, spray foam looked like my worst nightmare
Useful Tools: A knowledgeable insulation contractor

Flashers
Though I haven’t posted for a few months, slow and fitful progress has been made. First off, let’s talk about the front and rear flashing lights that all busses have.

Most busses I see have 8 flashers, four front and four rear, that are a mixture of red and amber. Crowns only have two front and two back, all red-colored lights. The relay that controlled these had been removed from my bus prior to sale, so they were non-functional when I got the bus. These light fixtures give the bus a really cool look, so I decided to follow the example of others here and re-purpose them.

This bus had been backed into something long ago (tree branch??), and while the damage had been fixed pretty well, the rear right flasher still leaked pretty badly. My intent was to seal everything up, then re-wire the back flashers as additional turn signals or brake lights. After taking them off in preparation for the re-seal, my wife and I were surprised to find out that we liked the look of the bus better without them. The purists out there will hate us for this, but we decided to leave them off. One less project for me! If anybody wants some Crown rear flasher assemblies, let me know!

Like many others here, I made the front flashers into additional ‘off-road’ lights. I’m not sure how often we’ll actually use these, so for now I replaced the PAR-46 red bulbs with the cheapest clear halogens that I could find - $18 fog lights from NAPA. LEDs would be cool, but at over $100 per bulb, I’ll wait to see how useful these lights are before shoveling out the cash for more lumens.

Wiring was very easy. There was a big empty spot in the relay panel below the front heater where the flasher relay had once been. The wires that had run to the relay were still in place, so I just connected them all together. Next, I pulled the two wires for the rear flashers off the distribution panel (not sure if that’s the right term), and labeled them as unused. The front ‘off-road’ lights now turn on with a flick of the original big red switch, and the red ‘FLASHERS’ warning light still turns on in the dash, which I kinda like.

I'll upload some pictures of the lights with my next post

Insulation
We’d decided on spray foam early on. I assumed that it would be much cheaper to do it myself, since everything else always is. So, I spent a couple months researching which DIY pack was best and watching YouTube videos of how to apply and trim the foam. Then I actually read the instructions for one of the brands (Tiger Foam, I think). It said that you could use a respirator if applying the foam in larger structures, but in smaller spaces you need to have externally supplied air. That freaked me out a bit, so I started looking into local insulation contractors. The first place I called was a small family-owned business that came out to give me a quote of $884, installed and trimmed to the bus ribs. That was only $100 more than my cheapest materials estimate! I didn’t call anybody else for a second quote. This was a no-brainer.

Rear of bus before insulation. The little white blocks of EPS are stuck overtop of clearance lights and backup camera. This is so that I can easily find and dig them out later if necessary.

A few weeks later, the insulation team showed up at my house, with everything they needed built into a custom enclosed trailer, including a big diesel generator. They masked off everything but the roof and went to work. It took them all of that day and most of the next to finish the job. I estimate 36 man hours to get it all done, with nearly all of that time devoted to trimming. And it looked like hot, miserable work. I am so, so glad to have paid that extra $100 to not have to do it myself!


I’m convinced that the insulation company lost money on this job, but they stuck to their word and only charged me $884. My guess is that they’d only done residential work to this point – spraying between studs where very little trimming is necessary. I would definitely recommend these folks, but I’m pretty sure the next time they quote a school bus job it’s going to be MUCH more expensive!

Edit: I forgot to mention that we only had them spray foam the roof. I'll be using foam board below the windows.

[Tejon7]

Hi Crown Guy, thanks as always for sharing your knowledge. Per usual, I'm going to have to mull this all over for a while and see what shakes out. I'm still having "ah-ha!" moments from a post you wrote several months ago! The next time I'm under the bus I'll take some pictures of that coolant heater. Today's job of upgrading the front door takes precedence, though!

[Tejon7]

I don’t think I’ve mentioned it yet, but we’re doing this conversion in a very small space. We knew from the onset that the bus needed to be right outside our front door if we were ever going to finish converting it. Kudos to those people who are able to park their bus hours away from home, yet still summon the will power to commute to it day after day to work on it. We’re not capable of that. So… it’s parked alongside our small house, on a tiny lot, in the middle of town. It’s a 40’ bus crammed into an 11.5’ wide slot between our garage and fence. Also, I can’t just pull it out into the open to work on it. We had to temporarily remove 16’ of our fence to get the bus parked, so it’s basically stuck here until we finish converting.


I’m mentioning this now, because my next couple posts deal with exterior work. Because I’m working in a really tight space, any work on the outside of the bus takes longer and is somewhat more difficult than it might be for somebody with more elbow room.

Progress: Decals removed
Time: ~4 hours (About ½ finished)
Difficulty: Easy – after steep learning curve
Useful Tools: Rubber eraser wheel, Goo-Gone, wire wheel

Removing the lettering and decals on the bus wasn’t on my high-priority list, but I started doing it one day and it somehow snowballed into a multi-hour project. I really only needed to remove the “School Bus” lettering from the roof prior to painting, but I ended up removing about ½ of the total lettering and decals before I finally came to my senses and went back to my checklist of important tasks.

I failed to do my homework before starting the decal removal, and it caused a lot of headaches. First, I tried removing lettering using an oscillating tool with a scraper blade. That worked, but gouged the paint terribly. Then I tried wire wheeling the letters off. This also worked, and I was surprised at how little paint damage it did, but took a long time. Next, I tried a flat razor blade. This worked better than other methods, but was a huge pain when I tried to use it over any decals that weren’t perfectly flat.

Then, my brother-in-law suggested a rubber eraser wheel, which I immediately bought on Amazon for around $10. When it arrived, I chucked it into a high-speed drill and started eating through decals. This thing makes a huge mess of rubber dust, but cuts through decals much faster than any of the other methods I’d tried. Also, the rubber wheel will mold itself to curved shapes, allowing me to cleanly remove lettering that was applied overtop rippled body panels.


The rubber eraser wheel was a standalone solution for most of the lettering on the side of the bus. The front and rear roof lettering and the thick reflective tape on the rear of the bus needed a little more elbow grease, however. I think this stuff had baked on in the sun, making it harder to remove. The rubber eraser wheel removed the outer vinyl part of the sticker, but left a thick layer of baked adhesive behind. After some trial and error, I found a method to kill the adhesive layer: Spray with Goo-Gone, use wire wheel to grind the Goo-Gone into the adhesive, let set for 20-30 minutes, then wire wheel again until adhesive removed. This method got ~90% of the tough adhesive off, but a few spots needed a second coat of Goo-Gone.