Diesel in Oil, Slobber Tube White Smoke

[RichardEntrekin]

Don't laugh, I am truly asking for a friend. Lot's of experience here, and almost always helpful.

As the header states there is diesel in the oil confirmed by Blackstone, and white smoke is puffing out the slobber tube. The engine is a Detroit Series 60 with approximately 100k on it.

Here is the rest of the story. The engine developed a bit of black smoke at idle and acceleration. Local DD shop diagnosed it as bad injector and replaced injector. While the valve cover was off the tech ran the overhead. Tech cranked engine and immediately pulled valve cover because " a valve sounded tight". Now engine has smoke, don't know what color, at the exhaust.

After much diagnosis and headscratching, the same shop pulls the head because one cylinder won't hold pressure. One of the exhaust valves is bent, and the mark in the top of the piston is not carboned over. Ok, this thread is not about what may or may not have happened. That is water under the bridge.

So the owner drives the coach about 1000 miles to his home after the work. That is when he discovered the white smoke at the slobber tube, and oil filler cap if opened. As stated earlier, Blackstone confirmed diesel in oil. No coolant in the oil.

I am thinking one of three things, but I am posting to get more possibilities or diagnostics. I am thinking that either the upper or lower o rings on the injector are fubar and diesel is either spraying into the overhead, or around the injector into the cylinder. Or, the original bad injector sprayed diesel into the cylinder and the rings are now leaking by.

The oil was changed and the coach was driven with no change in the smoking.

Any ideas?

Thanks for the help.

[Geoff]

The valve that was replaced cracked the piston so that clyinder has no compression and is letting the unburned fuel (white smoke) into the crankcase and out the breather tube.

[Ed Hackenbruch]

If the smoke at the exhaust is white, he has probably lost a valve.

[RichardEntrekin]

Geoff,

That is a possibility we had not considered. Oh no! I am thinking that you would have some white smoke at exhaust if a cylinder didn't have any compression. But it is a possibility.

Ed,

No smoke at exhaust.

[chessie4905]

Get an ir gun and take temperature reading from each exhaust port. Harbor Freight sells them reasonable. In fact many places sell them now.

[Geoff]

Geoff,

That is a possibility we had not considered. Oh no! I am thinking that you would have some white smoke at exhaust if a cylinder didn't have any compression. But it is a possibility.

Ed,

No smoke at exhaust.

If it was a two stroke with broken piston/low compression then you would have white smoke out the exhaust.  A Series 60 is 4 stroke, so the compression stroke is lost into the crankcase with a broken piston, and the exhaust stroke has almost nothing to push out the exhaust.

[RichardEntrekin]

A ha on the four stroke understanding. Thank you.

[luvrbus]

A bad center bore on 1 of the pistons probably has one that is low

[RichardEntrekin]

Clifford,

I am so ignorant that I don't understand exactly what bad center bore means? Can you explain?

If you mean the bore is out of round and the rings are leaking, I understand. But this happened magically after the head was removed to fix the bent valve. Prior to that no white smoke from breather.

[eagle19952]

why are you buying an engine ?
why isn't the valve bender coughing up...?
did I miss something ?

[RichardEntrekin]

Don,

My role is to try to help the owner get the engine diagnosed and fixed. There are many possibilities in the saga that led up to this. It is easy to jump to someone misadjusting the valve and causing the bent valve. It's hard for me to imagine an experienced tech cranking down on the valve lash hard enough to overextend the valve that far. I have heard hearsay that misadjustment of the jakes could have caused this, but I do not know. The tip could have come off the original injector, but that info is not recoverable.

Before any conclusions can be reached, the problem must be diagnosed and confirmed. At that point the owner can decide what, if any, is an appropriate conversation with the original shop.

[RichardEntrekin]

Just to update. Owner changed out oil, and drove coach pretty hard for about 300 miles including some long grade climbs. Still smoking a little bit. Oil sample did not show diesel in the oil. So no deep diving into the engine yet. Owner will drive and continue to check oil samples.

The optimistic thinking is the bad injector either dumped diesel into the cyl for a while before it was changed, and or the rings lost the seal because of the diesel wash. Change oil, drive it, and monitor oil for diesel.

Thanks for all the ideas.

[buswarrior]

Excellent report.

Drive it 'til it breaks.

Be sure he goes far enough north to run some hills that takes it to its knees for many minutes at a time, and then go back down and run up 'em again.

Hard to load an engine in Florida.

happy coaching!
buswarrior

[Geoff]

Could be that the shop installed a new valve without grinding the seat and it is now starting to seal, reducing the white smoke.  And/or the piston is cracked and the heat is increasing the fuel burn. 

A compression test would be nice, along with a TDC air pressure test to see if the air is leaking past the valves or into the crankcase.

[luvrbus]

Series 60 don't have what people call slobber tubes if is it blowing excessive smoke from the crankcase vent pipe as I read it is going to be liner or piston problem

good luck