7.4L Mercruiser - oil through the exhaust

[Fireman431]

2001 7.4L Mercruiser. 315 hrs. Engine runs great, but the raw water impeller took a crap without me noting the higher temp. The engine alarm sounded and it shut down around 230 degrees. I changed the impeller and the water is flowing just fine. The engine sounds great and runs well. My problem is raw oil running through the exhaust. Not a lot, but enough to create a sheen on the water. I checked and it's oil, not gas. No water in the oil pan and the oil isn't being burned in the chamber. What would cause oil to get into the exhaust manifold? Please say it's a $5.00 part.....

 

[Don S]

Re: 7.4L Mercruiser - oil through the exhaust

I doubt even 230? would hurt the engine, but I would check the engine oil cooler first. Remove the cooler, and drain the oil out of it. Then plug one side of the oil side and pressurize the other oil connection up to 50 or 60 psi and hold the cooler underwater and see if you get any bubbles.

 

[PanchoCC]

Re: 7.4L Mercruiser - oil through the exhaust

I have this same problem.
Question: How would a failed/leaking oil cooler create a slick through the exhaust ?
Thanks

 

[Don S]

Re: 7.4L Mercruiser - oil through the exhaust

The oil leaks into the cooling water in the oil cooler. The water then goes thru the engine and exhaust system for cooling and exits through the transom shield and prop.