8V71 underwent a recent in frame overhaul, new cylinder kits, heads, bearings, water pump etc.

Right bank cylinders are pushing/pumping oil through the cylinder scavenging ports into the air box. Left bank is clear, blower is clean.
Any ideas? I have trouble believing all 4 pistons on the same bank have oil control ring problems. something must be common to all four cylinders such as the head, but am not understanding where the problem is originating from. any help is appreciated.

John

[email protected]

 

I'm gonna post your question to some guys I know that are diesel mechanics and very familiar with 2 stroke Detroits.

 

I got some input.

Is the engine turbocharged or naturally aspirated?

If turbo'd, the airbox drains have check valves that need to be oriented correctly (close to vertical). The check valves must also be functioning.

If natural, the drains should just go into some sort of catch can. Check to see if the drain line is plugged/pinched.

 

thanks much, don't want to tear the complete engine down for nothing. feel free to use my e-mail. [email protected]

john

 

Never been associated with two stroke diesels. With four-stroke diesels, happens when oil scraping (control) rings are fitted upside down.

Regards,
Tomy Zacharia

 

engine is naturally aspirated. drain lines are clear. we have the air box covers open and running the engine at 600 rpm we can see the oil pumping out of the cylinder scavenging ports into the airbox. If I saw one cylinder doing this I would figure that the oil control rings were upside down, but all four on the same bank.....I think something else is wrong.

john

 

I agree, and it is the same for two-stroke also. the trouble I am having is that this is a new overhaul, and that all four cylinders on the right bank are exhibiting the same phenomena. if it was just one, I would go with oil control rings on that cylinder. the left bank is clear.

john

 

ok we figured out the problem. Had to tear down the engine, and pulled all 8 pistons. found oil control rings were improperly spaced. also one piston had stuck rings from a fuel to lube oil dilution issue. We honed all cylinders, replaced and re-gapped rings as appropriate, putting back together today. Word to the wise, when installing kits put together from factory, take time to take apart and verify ring placement and orientation. I never would have thought so many could be messed up on one engine, but there you have it. appreciate the input from you guys.

john

 

This board doesn't have too many mechanics on it (mostly controls guys), but I know what you mean about factory detroit parts. I have heard many stories about factory injectors being bad right out of the box.

Glad you found the problem.