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2-71 Detroit Diesel Spewing Oil From Exhaust


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  #1  
Old 09-20-2018, 11:58:49 AM
cocoabill cocoabill is offline
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Default 2-71 Detroit Diesel Spewing Oil From Exhaust

I just finished overhauling my 2–71 Detroit diesel generator. I put new rings in power honed cylinders and basically checked everything out and make sure it was in good shape. So I started up and ran really nicely but after about 15 minutes I noticed some black oil coming out of the exhaust manifold to muffler connection so I shut it down. I did some research on this issue and found out the first thing I needed was correct two stroke 40 weight oil not the multi viscosity 4 stroke stuff I was using, so I drained the oil and bought Delo 100-40. The engine started right back up but after running again for a while so did the oil coming out the exhaust. So the other two culprits mentioned in online post are broken oil control rings which I was pretty careful when I installed, or leaking blower seals/clogged blower vent lines (I don't see any vent lines). Anyone here have an idea on how to narrow down source of the problem?

Thanks
Bill
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  #2  
Old 09-20-2018, 12:52:09 PM
CBarth66 CBarth66 is offline
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Default Re: 2-71 Detroit Diesel spewing oil from exhaust

I would think more toward the blower shaft seals leaking. My cousin had one of those engines in a 440 JD dozer. The seals leaked so bad it made the engine run away once. He got it shut down before it blew!
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Old 09-20-2018, 01:10:35 PM
ScooterBob ScooterBob is online now
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Default Re: 2-71 Detroit Diesel spewing oil from exhaust

You'll probably have more of the right folks reading this thread if you post in the Vintage Diesel forum here...

https://www.smokstak.com/forum/forumdisplay.php?f=60

I suspect one of the site moderators will move it there once they see it.

Nice looking engine by the way.
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Old 09-20-2018, 02:09:41 PM
K-Tron K-Tron is offline
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Default Re: 2-71 Detroit Diesel spewing oil from exhaust

If the blower rotors are blackened and soaked in oil, that is where you should start looking. If the blower rotors are still clean, chances are the oil is coming from the cylinder itself. Im not sure how you honed the liner but if you used a ball hone the liner is garbage. Ball hones will knock the sharp edges off the ports in the liner and allow excess oil to get past the rings. Detroit Diesel pistons are installed in a long tapered ring compressor that fits onto the bottom of the liner. If you did not use the right ring compressor, or perhaps installed the piston from the top of the engine you most likely damaged the oil control rings when they were forced past the liner openings. Detroits also do not like to be run at idle for extended periods of time without a load. Wet stacking will occur, but with how short of a run time you have on your engine it sounds to me like a bad oil control ring or a bad blower seal.

Chris
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Old 09-20-2018, 02:30:52 PM
ronm ronm is online now
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Default Re: 2-71 Detroit Diesel spewing oil from exhaust

Quit idling it & work the snot out of it for a while before you start tearing it apart. The rings aren't seated, & never will be until you put a load on it.
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Old 09-20-2018, 02:49:21 PM
Wayne Rosier Wayne Rosier is offline
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Default Re: 2-71 Detroit Diesel spewing oil from exhaust

After reading all the post, I totally disagree with ronm and 100% agree with K-tron. I worked with Detroits for 30+years and if the source of oil is coming from the blower and you try to run the snot out of it, you very well may end up with a pile of parts because they will run away with you given too much oil to the combustion chamber. Believe me I've seen it happen twice in the 30+ years of working on them. Like K-ton said, take a look at the blower rotors and see if they have oil on them, if they do the seals are leaking.
Good Luck
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Old 09-20-2018, 02:52:20 PM
Vanman Vanman is offline
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Default Re: 2-71 Detroit Diesel spewing oil from exhaust

Agreed- leaking blower seals are nothing to take chances with!
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Old 09-20-2018, 03:17:58 PM
miltruck miltruck is offline
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Default Re: 2-71 Detroit Diesel spewing oil from exhaust

Really need to know how the rebuild was done. If it was simply a re-ring job without removing the sleeves then the rings are pretty much going to be toast. If the engine had a lot of hours and the ring job was done right but the blower was untouched, then the seals in the blower are junk; hard & brittle and maybe even broken. There are two air box drains on a 2-17, one on each side and if there is any amount of oil coming out of these then the blower is the major suspect. Ours had bad seals and blew oil out of the drains like an oil well. Fixed the seals and engine was happy, no more oil. Seals came out in pieces. Can also take off the side cover and look into the air box. That may tell you something too.
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Old 09-20-2018, 04:04:05 PM
Odin Odin is offline
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Default Re: 2-71 Detroit Diesel spewing oil from exhaust

Check the blower seals first! A runaway can blow the engine apart if you fail to stop it in time.

But if the blower is clean, then try working it a little to see if it breaks in and behaves. If that doesn't help, something went wrong and it probably needs different rings or a new sleev.e
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Old 09-20-2018, 04:10:47 PM
miltruck miltruck is offline
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Default Re: 2-71 Detroit Diesel spewing oil from exhaust

https://www.smokstak.com/forum/showthread.php?t=100613
These are the original photos of our 2-71 set. If you look real close to the fuel filter side of the engine, near the fuel pump you can make out a hard line; this is the drain from the air box on the right side of the engine. The left side drain exits from under the blower. It is tough to look at the blower rotors on the 2-71 as the intake is part of the blower housing.
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Old 09-21-2018, 08:15:07 AM
cocoabill cocoabill is offline
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Default Re: 2-71 Detroit Diesel Spewing Oil From Exhaust

Thanks for all the great advice, this was an low hours engine that had sat for 30 years replacing my original engine that had sat for 3 years unknowing filled with rain water. The new engine looked good but decided to do a re ring job and yes I used a ball hone. Liners were removed and I used a ring compressor and was pretty darn sure I did not damage the rings.

engine has run for a total of about 30 minutes without any load other than spinning the generator rotor which is not wired yet to do any generating. I plan to open up the blower access and see what it looks like, I am hoping it's seals as they were the originals now 50 years old.

I'll report back again thanks for all the help!
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Old 09-21-2018, 09:01:24 AM
cornbinder89 cornbinder89 is offline
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Default Re: 2-71 Detroit Diesel Spewing Oil From Exhaust

I will 2nd the importance of loading the pistons from the bottom and using the CORRECT ring compressor. If you loaded from the top, no matter what ring compressor you used, it can damage the oil control rings which are never supposed to pass the ports. When loaded from the bottom, only push the piston far enough in so the bottom of the piston is in the liner.
If you didn't pull the liners, you couldn't have loaded from the bottom, so there is a chance the oil rings are damaged.
Also, on lined engines it is not recommended to hone, just replace liners.
I missed the last post where you did say you pulled the liners, sorry, but good info to keep in mind anyway.
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Old 09-21-2018, 09:03:16 AM
ronm ronm is online now
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Default Re: 2-71 Detroit Diesel Spewing Oil From Exhaust

Quote:
Originally Posted by cocoabill View Post
and yes I used a ball hone.
Well then...the plot thickens.
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Old 09-21-2018, 04:55:09 PM
cocoabill cocoabill is offline
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Default Re: 2-71 Detroit Diesel Spewing Oil From Exhaust

I pulled the little access plate on the top of the blower and can see quite a bit of oil around what must be the push rod tubes, it's hard to tell if it's coming out of the cylinder or being sprayed in from blower, see attached picture. Question is can I run the motor with the blower access plate removed and watch to see what way the oil is coming from or would that just be a giant mess?

Is there any way to test oil control rings or is the blow by the test? I really hate the idea of pulling this apart again, blower would not be that bad. If it has to happen it will, just may be a future project instead of a completed one.
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Old 09-21-2018, 05:24:58 PM
miltruck miltruck is offline
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Default Re: 2-71 Detroit Diesel Spewing Oil From Exhaust

Don't try and run it without the plate on, it won't start and if it could it would blow oil all over you.
I would start with the blower seals first. If they are 50 years old there is no question that they are bad. If you do it yourself just be real careful with the shims and washers on the shafts, don't mix them up as you will disturb the timing of the rotors and they will rub together and wreck things bad. Have to get a manual to make sure you do it right.
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Old 09-21-2018, 08:49:14 PM
cornbinder89 cornbinder89 is offline
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Default Re: 2-71 Detroit Diesel Spewing Oil From Exhaust

You can run a 6-71 with one plate removed, Or at least at idle, I don't think a 2-71 would run. There shouldn't be a lot of oil in the air box. If there is you need to find out where it is coming from.
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Old 09-24-2018, 10:35:19 AM
cocoabill cocoabill is offline
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Default Re: 2-71 Detroit Diesel Spewing Oil From Exhaust

I built a clear Plexiglas plate to replace the blower access cover and before installing cleaned area out with some parts cleaner so it was dry. I installed clear plate and ran motor, I did not see oil coming from blower but it looked more like it was collecting around push rod tubes, maybe coming down from top of tube, but hard to see, could also have been coming out of from cylinder port. This is my third 15 minute run on motor and oil problem seams to be less, maybe rings are just taking a while to seat.


Does anyone know if there are push rod tube seals on this motor, don't recall replacing them and none of the manuals I have talk about them. Also don't see exhaust valves seals on exploded view of the head?


Thanks
Bill
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Old 09-24-2018, 02:25:26 PM
Mark Schneider Mark Schneider is offline
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Default Re: 2-71 Detroit Diesel Spewing Oil From Exhaust

No valve stem seals that I know of.
Excess crankcase pressure could move raw oil down the valve guides into the exhaust ports. If this much oil was getting into the combustion chamber it should cause excessive smoke. Try running it with the oil filler cap off.
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Old 09-25-2018, 09:16:03 AM
miltruck miltruck is offline
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Default Re: 2-71 Detroit Diesel Spewing Oil From Exhaust

Is the crankcase vent system all clear and open? As noted, Detroit's will build crankcase pressure even in a brand new engine just by leakage from the blower and air box. Can't see the left side of the engine in the photo, but it looks like there is no venting in the valve cover. Original equipment venting on the 2-71 is part of the governor housing/mount and looks like an upside down U. On our unit, with the odd electric governor, the original user just had a hose attached to the side of the mount and laid it down under the set. Because the blower seals were so bad, it blew oil all over the place, plus the air box drains had oil catchers attached to contain all the other blow-by. In trucks, this is what they refer to as the truck "marking it's territory". When I fixed the blower, I drilled the valve cover and installed a Mopar valve cover breather w/ hose to vent the crankcase. Works very well and being located on the very top of the engine, there is no condensation anywhere in the top-end (which is very common if not run @ for extended periods to get good and hot).

Good suggestion to try and run it without the cap on and see what goes on.
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Old 09-25-2018, 09:27:07 AM
ronm ronm is online now
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Default Re: 2-71 Detroit Diesel Spewing Oil From Exhaust

You've run it for 45 minutes then, with no load? At what RPM? Slow idle? Just sayin'...

Is the air box drain open? You have never said anything about it...
All these Detroit experts obsessing about blower seals...there are simpler & more likely problems being ignored.
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Last edited by ronm; 09-25-2018 at 04:06:29 PM.
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