Journey with Confidence RV GPS App RV Trip Planner RV LIFE Campground Reviews RV Maintenance Take a Speed Test Free 7 Day Trial ×


Reply
 
Thread Tools Display Modes
 
Old 04-16-2016, 04:13 PM   #21
New Member
 
Join Date: Mar 2016
Location: Lehi, Utah
Posts: 6
Year: 1985
Chassis: Crown Supercoach
Engine: Cummins 855 (300 HP)
Rated Cap: 92 Passenger
Howdy! I bought its sister bus, the '85 tandem. It had a 300hp Cummings 855 in it, so my experience won't help you much, but it started right up after we installed new batteries in it.

It needs some brake and suspension work, but the engine runs great.

takoisam is offline   Reply With Quote
Old 04-16-2016, 05:09 PM   #22
Bus Geek
 
Robin97396's Avatar
 
Join Date: Feb 2016
Location: Willamina, Oregon
Posts: 6,409
Coachwork: 97 Bluebird TC1000 5.9
Nice buy. Many of us were watching that group of buses.
Robin97396 is offline   Reply With Quote
Old 04-17-2016, 07:41 AM   #23
Bus Geek
 
Join Date: May 2009
Location: Columbus Ohio
Posts: 18,707
Year: 1991
Coachwork: Carpenter
Chassis: International 3800
Engine: DTA360 / MT643
Rated Cap: 7 Row Handicap
Quote:
Originally Posted by Kipin View Post
I never knew a diesel engine could or would do that. Is that with all diesel engines or just the older ones and what causes that to happen?
Any diesel engine CAN run away... in a gasoline engine you cointrolled the air getting into the engine for throttling it.. in a diesel engine you are controlling the FUEL getting into the engine..

a runaway occurs if something else other than the diesel fuel becomes the Fuel for the engine.. ..

on an old diesel engine where the rings are in bad shape its entirely possible to suck enough oil into the cylinders on an intake stroke that it could conceivably burn and make power causing the engine to run away..

the only way to stop it is to cut off the air to the engine.. cover the intake with somehting HEAVY.. or a CO2 fire extuingisher has been used..

I dont klnow much about 2 stroke diesels (the 671) and why they tend to have a higher chance of running away.. (im sure someone can explain why)..

I saw it happen to an old tractor one time but was easily stopped because the owner kept a piece of heavy plywood handy just for the occasion and stopped it before damage was done..

-Christopher
cadillackid is offline   Reply With Quote
Old 04-17-2016, 12:38 PM   #24
Mini-Skoolie
 
yeggs's Avatar
 
Join Date: Jan 2015
Location: Oakland, Ca
Posts: 58
Chassis: Crown Supercoach
Engine: Detroit Diesel 6-71 Mid-ship
Rated Cap: 78
Early Progress

Hey Everyone! Time for an update!



Seats coming out:



I used a 1/2" and 9/16" socket on a swivel and an impact driver, no problems. I checked out a sawzall and angle grinder from the library, but didn't need them. What, your library doesn't let you check out dangerous cutting tools? Sometimes I love this town.



I pulled about 2/3 of the seats out so I could get to the engine access hatch. Would of done them all, but I need to move stuff around to make space to "process" all these super heavy things and get them to the scrapper.



Darn gum chewing kids *shakes fist*

yeggs is offline   Reply With Quote
Old 04-17-2016, 01:00 PM   #25
Mini-Skoolie
 
yeggs's Avatar
 
Join Date: Jan 2015
Location: Oakland, Ca
Posts: 58
Chassis: Crown Supercoach
Engine: Detroit Diesel 6-71 Mid-ship
Rated Cap: 78


Here's the side of the engine, aka the top of the engine in my configuration through the hole in the floor. Big-!@# starter, and the rectangle with the two shafts is the blower. That universal joint is the shift linkage.

I spent the better part of an afternoon just poking around and familiarising myself with the layout of the DD 6-71. For the record and future searchers, the turbocharged version, like the one I have here, does not have the emergency air shutoff on the intake manifold, as the internet hive mind tells me the NA versions do. But between the good suggestions from this forum about keeping a CO2 extinguisher on hand, familiarizing myself with the throttle/fuel mechanism, and some amount of reckless abandon and uncontrollable amount of just wanting to f-ing do it, I fired her up yesterday!

She caught almost right away! I have to crank my pickup longer on cold mornings! 2 fresh batteries, a tank of 10 YEAR OLD diesel. What a racket! I shot some video that I'll upload at some point, but here's where I'm at:

She starts. She airs up. She blows huge grey clouds of smoke. There is a pronounced knock that sounds like one cylinder misfiring somehow.

The plan for next week:

  • Start her on clean diesel with a bunch of that miracle engine/injector cleaner stuff. Anyone have suggestions?
  • Since that's unlikely to actually do anything, dive on into the engine. Start at the top, pull the valve cover and injectors.
  • Test the injectors, maybe try to service them, maybe replace them.
  • If nothing obvious wrong with the injectors, use the injector hole to do a compression and leak down. Actually, I'll probably do this anyway
yeggs is offline   Reply With Quote
Old 04-17-2016, 01:28 PM   #26
Mini-Skoolie
 
yeggs's Avatar
 
Join Date: Jan 2015
Location: Oakland, Ca
Posts: 58
Chassis: Crown Supercoach
Engine: Detroit Diesel 6-71 Mid-ship
Rated Cap: 78
@Robin Thanks for the CO2 Extinguisher tip!

@serpant Thanks for sharing the reckless abandon. I knew coming into this that a $500 bus would be a self-taught class in the inner workings of the 2-stroke diesel and not a drive it off the lot kinda deal. My style is always to take it apart and see how it works anyway, so might as well start with something that needs work. If you can't open it, you don't own it, as they say, and I'd rather learn it inside and out in my workshop then on the side of the highway some night!

@opus and @tango (and for future searchers) the way the intake and air filter is set up, it'd be hard to smother the air intake without cutting something permanently. Very good point about not using a rag or your hand on a turbocharged diesel!

@crazycal They were listed as having cummins 220's, but I can assure you that I've been wrenching on a Detroit! Also, they were listed as "ran when parked" but the huge maintenance log I have indicates that this one was having engine problems when they mothballed it. Learn from this, future bus shoppers, gov deals dot com doesn't have the most reliable descriptions! On the other hand, the contact person was extremely friendly and helpful, and I got a 38Klbs bus for $550, so, as with all things, trust but verify!

@cowlitzcoach Great Info! The build plate says it's model A-426TAC-275/80 and the tires are 11 R 24.5. On the block, I cleared the crap off the id stamp plate and can read the serial number, but the model number is behind a coolant hose so I can't read the last four digits... you know, the important, relevant ones... But the ones I can read tell me it's a 6-71 for vehicle applications! Ha! Defiantly not electronically controlled, and has a bunch of pneumatic actuators/solenoids on the coolant and throttle systems.

@takoisam Hey! Glad you're here! Cool Bus!
yeggs is offline   Reply With Quote
Old 04-17-2016, 01:29 PM   #27
Bus Geek
 
Robin97396's Avatar
 
Join Date: Feb 2016
Location: Willamina, Oregon
Posts: 6,409
Coachwork: 97 Bluebird TC1000 5.9
I hate to tell you this at this point, but when they say "must be towed", you only have to tow it off the lot. Granted you can get in trouble fixing something on the side of the road, but I've bought stuff and fixed it just outside the gate of the auction. If you had your batteries and filters with you, you could have stopped anywhere once you left the property pickup area. That seems like an awfully high tow bill.
Robin97396 is offline   Reply With Quote
Old 04-17-2016, 01:37 PM   #28
Mini-Skoolie
 
yeggs's Avatar
 
Join Date: Jan 2015
Location: Oakland, Ca
Posts: 58
Chassis: Crown Supercoach
Engine: Detroit Diesel 6-71 Mid-ship
Rated Cap: 78
Yeah, it was more then quoted. A bummer. But also, had no plates and had to go about an hour and a half up the highway. What are yah gonna do?
yeggs is offline   Reply With Quote
Old 04-17-2016, 04:48 PM   #29
Bus Geek
 
Robin97396's Avatar
 
Join Date: Feb 2016
Location: Willamina, Oregon
Posts: 6,409
Coachwork: 97 Bluebird TC1000 5.9
It's so cool this seems to be working out for you. I've wanted one of those since I was a kid in grade school (older Crown obviously).

You're misunderstanding the invisibility of a big yellow bus. Most people don't look twice, and they don't cut you off on the highway like with a normal POV.

This time I was legal, but I had tinted windows and there's no way to see the temporary sticker in the back window. I drove around for the next two weeks and never got stopped. I know I've got to paint before I go interstate, but I like the more respectful way drivers act toward yellow buses.
Robin97396 is offline   Reply With Quote
Old 04-24-2016, 06:44 PM   #30
Mini-Skoolie
 
yeggs's Avatar
 
Join Date: Jan 2015
Location: Oakland, Ca
Posts: 58
Chassis: Crown Supercoach
Engine: Detroit Diesel 6-71 Mid-ship
Rated Cap: 78
engine work

Started getting into the engine...

Oooo, look, I have Jake Brakes! Bonus!



I wasn't expecting them! There's a covered knock-out on the dash panel for the exhaust brake switch. My working theory is that the school district disabled them because of noise complaints. I don't know much about them. Anyone?



Here's a cylinder with the injector pulled. The first one took me a couple hours to figure out. After that it was more like 20 min per. This is a 2-stroke diesel, so all 4 of those valves are exhaust. The intake is down at the bottom of the cylinder. Three rocker arms, the middle is for the injector, the two outside ones for the exhaust valves. The injector sits in that copper sleeve; the sleeve is water cooled. The jakes sit on top of this and push down on the exhaust valves, changing the exhaust timing in a way I don't fully understand, increasing compression on downshifts and making that loud noise that you hear from decelerating trucks. The yellow wire nuts are on the fuel line flare nuts just to keep things clean.



And there they all are. 6x 7G70 injectors. I don't know much about the "G" series injectors, I think they might be california CARB specific? Anyone know? The injectors are all mis-matched, some with rebuilt stamps, some not, with what i think are date codes all over the place, from 78 to 89.

Next up: Compression and leak down tests! Then, deciding whether to diy a injector pop tester, or bring them to a shop... probably would be a good idea to try to make friends with someone with more DD experience...
yeggs is offline   Reply With Quote
Old 04-24-2016, 06:54 PM   #31
Bus Crazy
 
opus's Avatar
 
Join Date: May 2010
Location: Montana
Posts: 1,626
Year: 1995
Coachwork: Blue Bird
Chassis: All-American R/E
Engine: 8.3 Cummins
Rated Cap: 72
I thought that rocker cover was the tall version, sweet deal. The smartest thing you could now now is to make very good friends with a 2 stroke person.

You should go over to Bus Conversion Magazine forum and ask around.
opus is offline   Reply With Quote
Old 04-26-2016, 12:34 PM   #32
Skoolie
 
dmattarn's Avatar
 
Join Date: Oct 2015
Location: Metro Detroit, MI
Posts: 120
Year: 1999
Coachwork: Amtran
Chassis: International
Engine: DT466E Allison 3000
Rated Cap: 84 Kids/56 Adults
AWESOME BUS!!!! I dont know your level of mechanical experience inside engines and all that, it seems pretty high, but I'm in diesel mechnic school right now and I can tell you if you are planning on putting it all back together without replacing/rebuilding, try to label everything and put it back exactly where you found it. The wear surfaces on valves, rocker arms, etc will be matched exactly how they were and mixing all that up could potentially cause problems later down the line.

Awesome to see someone with an older crown, I absolutely love that body style. I'm looking forward to seeing the rest of your build!
dmattarn is offline   Reply With Quote
Old 04-30-2016, 07:48 PM   #33
Mini-Skoolie
 
yeggs's Avatar
 
Join Date: Jan 2015
Location: Oakland, Ca
Posts: 58
Chassis: Crown Supercoach
Engine: Detroit Diesel 6-71 Mid-ship
Rated Cap: 78
Progress

The best Diesel Engine troubleshooting advice I ever got, and that I will now pass on is:

"Diesel Injectors are guilty until proven innocent."

So far on this 500K Detroit Diesel 6-71, I've pulled the cover, Jake Brakes, and all six injectors. I dropped them off at a local place, Diamond Diesel and Turbo here in Oakland, for a pop test and eval. $30 later, and I've found the most likely cause of my one-cylinder misfire:



Injector #4, Stuck Open



The injectors on my Detroit are "unit injector" type. That is, there is no high pressure injector pump like most of you non-Detroit folks have. (I actually have never seen this set up before and can't think of another example). Here, low pressure diesel is supplied to the injectors. A check valve closes, the rocker arm pushes down, and the large volume of diesel is forced into a much smaller space, increasing it's pressure dramatically (something like 400psi, I think, without looking at the book) until the plunger reaches the bottom of the injector and the needle valve opens, spraying an atomized, high pressure mist of diesel through a pin-sized hole and into a hot and waiting high pressure cylinder, where it explodes and makes a cool rumbbly diesel noise and sometimes helps move the bus forward. Of course, if your cylinder #4 and think you can just open your needle valve whenever, you're just gonna dribble some lo pressure diesel into the cylinder and just make a smokey mess and cause a misfire. No high pressure, no explosion, engine no work.

So anyway. 95% chance I found the problem. I ordered a new injector, $50 shipped. Should be here thursday. Then I just have to put it all back together and completely redo the timing.

I'm still going to try and do the compression and leak down since I have all the injectors out... if I can source the f_____ing adapter. Most diesels, you thread the compression tester into the glow plug hole. Detroits have no glow plugs, so you have to do the test through the injector hole, and therefore have to source a "blank" injector adapter... for an engine that hasn't been made for 30 years... ugg.

Meanwhile:

All the seats are out, and I've been playing with floor plans by using masking tape on the floor.

Also, stripping the seats for the scrapper. Super unrewarding with scrap prices low like this. I know I'm not gonna get anything for them, but I have to do something with them.



Beer and sledgehammers are my preferred tools, but it's still kind of a drag.

I also pulled the "light channel" raceway aluminum extrusion down.



My plan is to use this as a raceway for the new 12v stuff I'm going to put in.

As an ex- east coaster who has spent some time in Florida, I was really hoping that this dry California air would mean no moldy insulation to deal with.

Nope:



Ewww.

I trashed that stuff behind the light channel... but I'll tell you right now that I'm not drilling out the approximately 12 million rivets that hold up the ceiling panels to replace the insulation up there. If it was screwed together, maybe. But these 50 million rivets? Life is too short. I'm thinking that I'll great stuff above he channel to "sort of" seal the no-doubt gross fiberglass "up there."
yeggs is offline   Reply With Quote
Old 04-30-2016, 07:52 PM   #34
Mini-Skoolie
 
yeggs's Avatar
 
Join Date: Jan 2015
Location: Oakland, Ca
Posts: 58
Chassis: Crown Supercoach
Engine: Detroit Diesel 6-71 Mid-ship
Rated Cap: 78
Tune in next time for:

Tanks! Pluming Rough ins!

Toilets: composting or flush? Call in and let us know what YOU think!

Paint prep!

Flooring Removal!

All this and more, on the next episode of *dramatic movie trailer voice*

Escape From Oakland
yeggs is offline   Reply With Quote
Old 01-07-2017, 08:50 PM   #35
Mini-Skoolie
 
yeggs's Avatar
 
Join Date: Jan 2015
Location: Oakland, Ca
Posts: 58
Chassis: Crown Supercoach
Engine: Detroit Diesel 6-71 Mid-ship
Rated Cap: 78
Deep into the 2 Stroke

Hello Skoolie.net! It's been a while!

What have I been up to? Learning all about old school 2 stroke diesel engines. Not quite the project I thought I'd signed up for, but life is like that... especially for people that impulse-buy $500 school buses.

So, let's dive into this: Last I posted, I had figured out that #4 injector was stuck open. As it turns out, that was not quite the whole truth, and the "lead" that the injector shop gave me missed an important detail.

The tip of #4 injector was missing. Straight up gone. And things don't just disappear... the tip wasn't attached, but it must of gone somewhere....



That's the turbo, the exhaust side. You can see the damage there to the exhaust-side turbine. The hardened metal tip of the injector failed, fell off, and went for a ride all the way through the engine. This is a picture of classic foreign-body damage to a turbo. This is now an expensive paperweight. Can't be used like this.

With that much damage to the turbo, and the misfire, I had to tear deeply into the engine to see what else that little bit of metal messed up...



Heres the head coming off. Solid cast iron! Quite a load-handling adventure!



and this is the "bottom" of the engine... the passenger-side in my odd, sideways configuration.



Here's a picture of me testing the valve seal. This is the bottom of the head. I filled the exhaust passage with diesel and let it sit, looking for leaks. Little dribbles like this are OK; if it dumped out the diesel I'd have to address the valves and seals. If you look closely at the bottom right valve, you can see the impact "nic" from the injector tip. Ugly but serviceable.



Here's a detail of a couple of the pistons. Down there at the bottom is the intake. These 2-strokes don't have intake valves at the head like a normal engine. Intake and scavenging are done via these openings, so as the piston bottoms out at the end of the stroke, these openings are uncovered and slightly compressed air is blown in.

Note the difference between the upper and lower coolant passages (the circles between the cylinders). I made a pretty big error on reassembly by not cleaning these enough. Note the difference between the rusty bottom one, and the top one that i cleaned with a dremel/die grinder with a scotchbrite type pad.



You see, if you don't prep your gasket surfaces, the gaskets can't do their job. These gaskets are to keep the coolant water out of the oil. This pic is what classic water-in-oil looks like inside the valve cover. If you're yeggs, this means that you have to pull the head back off and try again...



This is a piston liner. They all had these year 2000 rebuild stamps, so I assume that the engine was rebuilt in 2000, driven for 7 years of service until the injector failure, then parked until I bought it.
yeggs is offline   Reply With Quote
Old 01-07-2017, 09:03 PM   #36
Mini-Skoolie
 
yeggs's Avatar
 
Join Date: Jan 2015
Location: Oakland, Ca
Posts: 58
Chassis: Crown Supercoach
Engine: Detroit Diesel 6-71 Mid-ship
Rated Cap: 78
What Happened?

So, what happened?

I have 2 working theories, and I've addressed both:

First, these Detroit Diesels have a lot of nicknames, and one of them is "leaking jimmy", and the internet is full of references to their habit of "marking their territory". This isn't really that bad -- they were designed that way. In fact, they even have an assembly called a slobber tube. The slobber tube is designed to dribble extra oil in the pressurized intake-air passage out of the block when the engine is off (a check valve is closed when the engine runs).

But this is california, so by 2000 dribbling oil on the parking lot was about as acceptable as stubbing out a cigarette on the bamboo-lined floor of your remodeled industrial building.

So someone covered it with some plastic and a hose clamp.

With nowhere to go but into the cylinder, the extra oil backed up into the cylinder, probably causing detonation/uncontrolled combustion and all kind of timing issues and very likely overheated or otherwise caused the injector to fail, cascading and making me tear apart the whole f____-ing thing.

The only other, less likely cause was water-in-fuel. Now, this thing had two fuel filters, but neither was a fuel-water separator. I don't think this was the issue, but I went ahead and replaced the first fuel filter with a racor fuel-water separator.
yeggs is offline   Reply With Quote
Old 01-07-2017, 09:04 PM   #37
Bus Nut
 
Carytowncat's Avatar
 
Join Date: May 2016
Location: Richmond Virginia
Posts: 932
Year: 1984
Engine: 366 Big block Chevy! :) w/ Stick shift
The mystery unfolds! awesome detective work

I hear that motor is a thing of wonder and beauty.
Carytowncat is offline   Reply With Quote
Old 01-07-2017, 09:11 PM   #38
Mini-Skoolie
 
yeggs's Avatar
 
Join Date: Jan 2015
Location: Oakland, Ca
Posts: 58
Chassis: Crown Supercoach
Engine: Detroit Diesel 6-71 Mid-ship
Rated Cap: 78
Onward

So... after an unexpected detour through the bowels of the engine, and a break for my pays-me-money job, the crown now has a running, throughly gone-through Detroit Diesel 6-71.

New (well, remanufactured) turbo.
Cleaned up pistons, replaced rings
New head gasket (twice, ugg)
New Fuel-water separator

Pulled, evaluated, cleaned and returned to service:
Cylinder liners
Head
oil pump
... pretty much everything, actually... Way too much to type out right now. The pistons, rods, liners and bearings were from 2000 and looked great, so I just put them back in.

And now, on to the ACTUAL conversion...
yeggs is offline   Reply With Quote
Old 01-07-2017, 09:36 PM   #39
Bus Nut
 
GreyCoyote's Avatar
 
Join Date: Mar 2016
Location: Danglebury, Tejas
Posts: 310
Year: 1999
Coachwork: Blue Bird
Chassis: IH 3800
Engine: Navistar DT466E
Rated Cap: 72 passenger
Well done, Yeggs!!! Way to hunt the gremlin down and kill it!
__________________
"You can finally say you have enough horsepower when you leave two black streaks from corner to corner"
(Mark Donohue, famed TransAm driver)
GreyCoyote is offline   Reply With Quote
Old 01-08-2017, 02:01 AM   #40
Bus Crazy
 
Join Date: Jul 2011
Location: Winlcok, WA
Posts: 2,233
I hope you spent the extra $$$ for the copper washers and new head bolts. If you didn't, your DD 2-cycle will dribble everywhere it goes.

The steel washers don't compress as well so you end up with space for leaks.

New head bolts are needed due to the stress you put to them when you torque them down tight. Used head bolts will torque up but will relax after you take the wrench off and they won't be holding on as tight as they are supposed to be holding.

Now that you have a basically new engine are you going to take the time and $$$ to make sure your radiator is clean and up to the task? 2-cycle DD's run hot anyway. A nice new and tight engine is going to run even warmer. If the radiator isn't up to snuff you will be over heating.

Good luck!
cowlitzcoach is offline   Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


» Featured Campgrounds

Reviews provided by

Powered by vBadvanced CMPS v3.2.3

All times are GMT -5. The time now is 09:46 PM.


Powered by vBulletin® Version 3.8.8 Beta 4
Copyright ©2000 - 2024, vBulletin Solutions, Inc.