Need help with old Cummins VT555-M

[Bowden]

I have two of these old engines in a 36ft boat. One engine is great and never gives any problems. The other one has a tremendous amount of blow by. The engine runs great, starts immediately even in cold weather, and has plenty of power. It has very little blow by coming from the oil pan when the dipstick is removed but is blowing like a leaf blower out of the valve covers at high rpm. At around 1200-1500 rpm a pulse of air can be felt coming out of the oil filler hole on the valve cover like it is a cylinder's compression leaking into the valve cover. Does anyone have any idea where this could be coming from? I know that usually blow by is caused from compression leaking by the rings but this seems to be going the other way. Any help would be greatly appreciated!

 

[InfernoB]

Check the valley covers. Many times one will find that the gasket between the valley cover and the portion of the intake in the head will split. Thus charged air will enter the crankcase causing what you describe.

You may be able to see it when you pull the valve covers by looking at the ports, but the best thing to do is pull the intake manifolds off. One other possibility of charged air entering is if a plug in one of he intake ports in the head fell out. The plugs are in for turbocharged engines, and tubes for naturals. Great engines for their time, but then the B was born... .....

Let me know if you have any other questions.



Mike

 

[Bowden]

Thanks Mike. I will definitely check that out. It's hard to find anyone that knows anything about these things around here and I didn't want to tear into it blind! Thanks again!



Max

 

[MN Cummins Lvr]

I am sorry, can't help you with the answer to your question, but would love to see pics of your boat and engines! Any chance you could post? Thanks!



Paul