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Old 04-24-2016, 06:54 PM   #31
Bus Crazy
opus's Avatar
Join Date: May 2010
Location: Montana
Posts: 1,615
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.
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Old 04-26-2016, 12:34 PM   #32
Almost There
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Join Date: Oct 2015
Location: Metro Detroit, MI
Posts: 75
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!
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Old 04-30-2016, 07:48 PM   #33
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Join Date: Jan 2015
Location: Oakland, Ca
Posts: 55
Chassis: Crown Supercoach
Engine: Detroit Diesel 6-71 Mid-ship
Rated Cap: 78

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.


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.



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."
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Old 04-30-2016, 07:52 PM   #34
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Join Date: Jan 2015
Location: Oakland, Ca
Posts: 55
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
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Old 01-07-2017, 08:50 PM   #35
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Join Date: Jan 2015
Location: Oakland, Ca
Posts: 55
Chassis: Crown Supercoach
Engine: Detroit Diesel 6-71 Mid-ship
Rated Cap: 78
Deep into the 2 Stroke

Hello! 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.
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Old 01-07-2017, 09:03 PM   #36
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Join Date: Jan 2015
Location: Oakland, Ca
Posts: 55
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.
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Old 01-07-2017, 09:04 PM   #37
Bus Nut
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Join Date: May 2016
Location: Richmond Virginia
Posts: 926
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.
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Old 01-07-2017, 09:11 PM   #38
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Join Date: Jan 2015
Location: Oakland, Ca
Posts: 55
Chassis: Crown Supercoach
Engine: Detroit Diesel 6-71 Mid-ship
Rated Cap: 78

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
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...
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Old 01-07-2017, 09:36 PM   #39
Bus Nut
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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)
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Old 01-08-2017, 02:01 AM   #40
Bus Crazy
Join Date: Jul 2011
Location: Winlcok, WA
Posts: 1,812
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!
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