Logo
FULL SITE MENU

Mercruiser 165 water in oil fine firt 2 times then blam nasty oil

F

firemanlowden

Member
"Mercruiser inline 6 165 hp. I

"Mercruiser inline 6 165 hp. I put new gaskets on last year. Heat, intake/exaust. It ran great first 2 times on the mississippi with no water in oil. then the 3rd time had a little bit in it and the 4th time out it was water instantly in oil. I took the head back off after compresion test because compression was fine and found that the head gasket was still good! head seems to have no cracks. The block did have a crack before I fixed it but had it JB welded closed. could it be my intake/exaust manifold??? I have lots of water shooting though exaust. Engine still runs great. Im confused"
 
Where is the location of the c

Where is the location of the crack w/JB weld? It may have gotten bigger. Have you laid a straight edge on the block and head surfaces to see if they are not warped? One or both may need machined to true the surfaces.

Is there water in one or more of the cylinders? That would indicate intake/exhaust manifold cracks.
 
The crack was just behind the

The crack was just behind the exaust manifold. It seems to be fime and not gotten bigger. there was no water in any cylinder and I had a extra head that I just got done putting on a few min ago. Havent tested yet. I aslo put on a differt intake/exaust I had extra also. The block was true yet. I havent looked at the old head yet but the new one just got resurfaced. I hope this works. thanks
 
"The downside of the inlines &

"The downside of the inlines (4 & 6) GMs, I had a new Sierra Manifold crack first time out, luckily was on the exhaust side, the replacement one hasn't cracked yet. The one that cam with the boat was cracked and prev owner ingested water from the intake side and bent the #6 Rod ( still usable somewhat ) Which put water in the oil, if it was running rough its probably from water injesttion killing the spark. Unless you cracked a cylinder, most likely its the int/exh manifold. Could be crack in the head."
 
"You can have water in the oil

"You can have water in the oil and water in the combustion chambers.

Manifold and or riser will allow water into the cylinders and you should pick that up by checking the spark plugs. Water in the oil could be a heat exchanger if it has one? cracked block, cracked head or head gasket problem"
 
"I don't know if this will

"I don't know if this will help your diagnosis or not, but here it is, anyway:

My exhaust elbow rotted out on the inside (Mercruiser 120). When cold it had clear water on the #4 spark plug and some leaked down past the rings into the oil. And it would not idle. Above idle it ran fine.

What was happening was that as long as the engine was running above idle, the exhaust had enough pressure to blow the water along with it. But at idle the exhaust could not blow out the water so it would dribble into the cylinder. And when the engine was shut off, the water would gradually seep down through the exhaust manifold and into the #4 cylinder because of the tilt of the engine.

It is easy to remove the exhaust elbow and look into it - if the nuts haven't rusted tight!
angry.gif
"
 
Started the old boat up today

Started the old boat up today after I put on a differnt head and differnt exaust/intake minifold. Runs like a champ and NO water in the oil anymore. YAhhoooo!!!! But was running on the muffs. Will test in river tommorow. Wish me luck. Thanks for all the help guys.
 
Back
Top