Logo
FULL SITE MENU

moisture in crankcase

V

vicpresnal

New member
4.3 with moisture in crankcase, no rise in oil leve, no milky oil, only slight steaming coming out of oil fill cap on valve cover, houseboat that we do not log many hours, mainly short trips. at one time i had bad intake manifold gasket, lots of water in oil then, it cleaned up after 4-5 oil changes, 2 years later still have steaming, could this steaming be left over from the large ammounts of pudding in the crank or do I have another problem. I do have the old one piece mercrusienr exhasut manifold that I have heard is a problem. My question is could I put a T in the plug hole on the intake manifold and then add pvc valves to the valve covers, run that into the T. Would this set up help suck the moisture out of the crankcase. Currently, no pvc, only a line run from the valve cover back to flame arrester , minimuim suction from the carb.. Help, my next optionis change the exhast manifolds, then head gaskets. Don't want to do this until a last resort. any suggestions?
 
only slight steaming coming out of oil fill cap on valve cover, houseboat that we do not log many hours, mainly short trips.
Click to expand...
If your engine is raw water cooled (lake/sea water) the the thermostat should be a 140 F. type. It takes alot of time at cruising speed to allow the oil to heat up and "boil" off the moisture in it left by the combustion process. Short trips just warm the oil...not hot enough to expel the moisture in the oil. I had a 4.3L w/140 F. T'stat and it almost always had water vapor coming out of the valve covers except when we were using it to ski. What you are experiencing is normal. Make sure you change the oil every season at a minimum. Make sure the T'stat is working.

How old are the manifolds? They will fail faster w/short trips...water vapor increases rusting. If they are ten years old consider replacing them w/quality exh. mans. It is cheaper to replace exh. mans. than to replace the engine due to water intrusion...it will occur when you least expect it. Osco and Barr are excellent A/M manifolds...GLM is NOT recommended; they have a porosity problem and sealing at the block issue on some of them...poor castings.
 
Re: moisture in crankcase.

guyjg said:
If your engine is raw water cooled (lake/sea water) the the thermostat should be a 140 F. type. It takes alot of time at cruising speed to allow the oil to heat up and "boil" off the moisture in it left by the combustion process. Short trips just warm the oil...not hot enough to expel the moisture in the oil. I had a 4.3L w/140 F. T'stat and it almost always had water vapor coming out of the valve covers except when we were using it to ski. What you are experiencing is normal. Make sure you change the oil every season at a minimum. Make sure the T'stat is working.

How old are the manifolds? They will fail faster w/short trips...water vapor increases rusting. If they are ten years old consider replacing them w/quality exh. mans. It is cheaper to replace exh. mans. than to replace the engine due to water intrusion...it will occur when you least expect it. Osco and Barr are excellent A/M manifolds...GLM is NOT recommended; they have a porosity problem and sealing at the block issue on some of them...poor castings.
Click to expand...

Yes manifolds are 12 years old, I will consder replacing, what about teeing into the intake for greater suction of the crankcase? How about a hotter t stat?
 
Re: moisture in crankcase.

Yes manifolds are 12 years old, I will consder replacing, what about teeing into the intake for greater suction of the crankcase? How about a hotter t stat?
 
Re: moisture in crankcase.

what about teeing into the intake for greater suction of the crankcase? How about a hotter t stat?
Click to expand...

Ayuh,.... Don't....

Yer tryin' to fix a Problem that doesn't exist...

Bein' in freshwater, ya might try a 160° T-stat,... Use a Marine gasket, if ya swap it out...
 
Re: moisture in crankcase.

vicpresnal said:
Yes manifolds are 12 years old, I will consder replacing, what about teeing into the intake for greater suction of the crankcase? How about a hotter t stat?
Click to expand...


There is nothing to consider, You must replace them. 12 years old! That engine is running on borrowed time!

Do not use GLM or HGE, Osco or Barr will do the trick.
 
I appreciate the positive input. What concerns me most is the other boats here at the marina do not seem to discharge this steam. I have twin 4.3's one of them it is barely visible, and the other is quite a bit more noticeable, leaving some white milkyness in the oil fill tube. Although when I pull the oil it appears ok. I have poured the oil in a plastic bag, and let it seperate. there is approx a half of a thimble of water in the very corner of the bag, with that said you still think condensation?
 
Had a similar problem with an engine that tended to steam a bit more then normal but had a closed cooling system .When i started to notice the coolant level dropping slightly over time, I pulled the intake and found the gasket had let go between the water jacket and the cylinder intake. I was burning coolant, hence the steam.
 
Back
Top