Mercruiser 4.3L V-6 water in oil... need help

[hawkf250]

Hello, I have a 1999 Mercruiser 4.3L V-6 EFI it has been running great all summer long until last weekend I went to take her out and it wouldnt start, it would spin over but never fire up. I took it home and started troubleshooting, Then I pulled the dipstick and saw milky oil, what would cause this other than a cracked block? Any help would be great, I just dont see a block cracking after a week of sitting.

 

[Bt Doctur]

Re: Mercruiser 4.3L V-6 water in oil... need help

leaky manifold and/or riser

 

[parasail]

Re: Mercruiser 4.3L V-6 water in oil... need help

Bad flappers allowing water back through exhaust. ?

 

[thumpar]

Re: Mercruiser 4.3L V-6 water in oil... need help

I would vote for intake manifold.

 

[Adirondack]

Re: Mercruiser 4.3L V-6 water in oil... need help

First step to diagnosos will be to pull the plugs and crank it over looking for signs of water coming from a cylinder to determin if it's getting in thru the cylinders, and which bank. Then a compression test. If good it's not head gasket. Most likely leaking manifold, riser, or bad flapper.

 

[hawkf250]

Re: Mercruiser 4.3L V-6 water in oil... need help

Thank you all for the quick replies, I will start the checks and report back when i find something.