Oil leak at Manifold gasket 3.0 Mercruiser

[JPrater]

I've searched iboats and can't find this problem anywhere else so I'm hoping to get some help. I have a 98 3.0 Mercruiser and there is oil bubbling up in one spot between the head and the manifold. It is under the back side of the carb. There is a small indetion in the block casting and oil recently started bubbling up. I kept finding oil in my bilge. There is no water in my oil so I'm pretty sure the block isn't cracked, it just appears to be lealing through the gasket. Anybody else had this problem? Am I missing a bigger problem? The motor has also been running slightly hot recently - not sure if it's connected to the oil problem. Any help would be appreciated!

 

[Bifflefan]

Re: Oil leak at Manifold gasket 3.0 Mercruiser

sounds like your PCV valve isnt working, or is plugged. this will cause pressure to build inside the engine and push out oil at the weakest spot.

 

[totx]

Re: Oil leak at Manifold gasket 3.0 Mercruiser

I have a 98 3.0 Mercruiser and there is oil bubbling up in one spot between the head and the manifold. It is under the back side of the carb.

Clean up and check again...

Sure the oil is not leaking from the valve cover?

If the oil is bubbling between the manifold and cylinder head.
I would think you have a bad manifold gasket.
But that is not causing the oil leak.

 

[fishrdan]

Re: Oil leak at Manifold gasket 3.0 Mercruiser

Yup, no oil passages between the manifold and head. Check the valve cover gasket.

 

[JPrater]

Re: Oil leak at Manifold gasket 3.0 Mercruiser

My thoughts were that there shouldn't be any oil there as well - however I just went and checked agian and it definitely appears to be coming from the gasket - it actually looks like the gasket was damaged right in that spot. Someone mentioned a stopped up PVC valve - could that potientially cause it to run slightly hot as well? The oil was under pressure coming out because it was bubbling up - looks like it has some air in it as well.

 

[totx]

Re: Oil leak at Manifold gasket 3.0 Mercruiser

My thoughts were that there shouldn't be any oil there as well - however I just went and checked agian and it definitely appears to be coming from the gasket - it actually looks like the gasket was damaged right in that spot. Someone mentioned a stopped up PVC valve - could that potientially cause it to run slightly hot as well? The oil was under pressure coming out because it was bubbling up - looks like it has some air in it as well.

As fare as I know there is no oil channels in the cylinder head ore manifold.

The oil have to come from valve cover (rocker cover in merc term).
But if you have a leaky manifold gasket, it would bobble if you have oil there.

Post a picture!

Positive Crankcase Ventilation (PCV) Valve
(If Equipped) - Don't think you have one, on the breathing house to carburetor ore in the valve cover.

 

[JPrater]

Re: Oil leak at Manifold gasket 3.0 Mercruiser

Thanks for the help again! I checked it out again and it was coming from the valve cover gasket. Apparently I have a small hole in the exhaust manifold gasket that was filling up with oil and shooting it up from between the head and manifold. Anyways, thaks for the input - it saved me pulling the manifold unnecessarily.