why does my 1985 Mercruiser 140HP engine oil look like a coffee milk shake after overheat?

[1KnoxArmor$]

why does my 1985 mercruiser 140 HP engine oil look like a coffee milkshake after overheat run?

 

[yamjer]

Water contamination. Ive changed my oil and filter twice. Looking at doing head gasket once i pull it out of water for the season.

 

[ThomW]

Water got into your oil somehow, somewhere along the line....now you need to figure out how and when so you can fix it.

 

[Scott06]

why does my 1985 mercruiser 140 HP engine oil look like a coffee milkshake after overheat run?

Likely a head gasket due to the over heat do a compression or leakdown test. Could also be the joint between manifold and exhaust elbow but if this were leaking you would see water in combustion chambers after running. Outside chance the manifold got hot and cracked the water jacket.