Could use help please

[BS]

I have a 1988 Z33 Crossbow with twin 354 Mags, the mechanic is telling me that with the big blocks there will always be a small amount of water in the oil due to condensation. This does not sound right to me. I would appreciate any information.

Thanks,
Bill

[David Ochs]

Bill, An aquaintance of mine that works for Pennzoil explained to me; The primary cause for users to change oil more often because of short trips is moisture in the oil. Without operating at temperature long enough, water doesn't sufficiently evaporate. This is the real reson that cold starts are hard on a motor, not neccesarily the infamous "dry start".
I would also question the notion that "big blocks" are more prone to excessive moisture in the crankcase. Perhaps the shear volume of the big motor requires more runnig time to dry out.
I'm sure some better explanations will be along.

[harbormaster]

I believe Digger experienced this problem last year at AOTH with his big blocks.

[MOP]

From what I have noticed over the years, its the run time and temperature that govern the amount of moisture. Cruisers engines stay very clean little to no muck, but bay fisherman, runabouts and ski boats have a lot more. It has to be all the stop and go. Fresh water cooled engines stay a bit better than raw water cooled. My engine has marginal breathing just the two hoses off the aluminum covers to the carb, but I have no moisture build up with 160 temp. Most all of my running is several miles. When I was into skiing my engines were always mucky.

[Donzigo]

I have a 1989 Z-33 with 454's, and have not experienced this condition. I boat in a warm weather climate; so, as MadPoodle said, maybe there are extinuating circumstances where you are. I do run for long periods of time. Usually my boating is done on weekends, usually for two hours of running time per day, and that converts into about 125 hours per year, FYI.

Good luck with the mystery.

[Howie]

Bill,

I have heard of moisture buildup due to low operating temperatures, however not specific to Big Blocks. I had a built 454 in my old boat and had a problem with water in the oil. After tearing my engine apart I found out that it was because of reversion. I was running the stock mercruiser exhaust with a beefed up cam...Big Mistake. The stock Mercruiser exhaust has got to be the worst design I have ever seen. It cost me an engine before I upgraded to stainless marine. Never had a problem again. So in short it could be the exhaust starting to go..They don't give you much meat between the exhaust and water jacket between the manifold and riser.

Howie

[MOP]

Good point on the reversion or exhaust water leak, if let go to long the rings stick and the water ends up in the oil. Do the dastardly deed! Taste a dab of the mucky oil if it is salty there is your answer. Tasting won't kill you lots of boat mechanics do it every day.

[BS]

I want to thank everyone for their replys, it was a major help.

The temp was only reaching 120, when the mechanic replaced the thermostat it seems to have solved the problem.

Thanks again,
Bill