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Please educate me on my engine re: manifold and riser

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lushka16

New member
I've recently purchased a 1981 Chris Craft 332 Commander with twin FWC 454 Crusaders. This is my first inboard, and I'm not very well educated on all the nuances.

After my shakeout cruise last week, I noticed water in the oil! All signs point to a leak from the riser and or header:

-Steam from exhaust
-Affected (stbd) engine exhaust hotter than port engine

I'd like to know the troubleshooting steps, so that I can properly diagnose and fix this problem. Where do I begin? Is there anything I can do to extend the life of the parts another season, so that I can work on this off season when money isn't so tight?

Second part of my question - how exactly does the raw side of my cooling system work? I have a raw water pump that pulls in raw water, runs it to a heat exchanger, the water accepts the waste heat from the engine, and that raw water is expelled through the exhaust. Do I have that correct? If I'm having a problem with the manifold or riser, how exactly does that cause raw water to enter into the oil?

Thank you!!
 
lushka16 said:
Second part of my question - how exactly does the raw side of my cooling system work? I have a raw water pump that pulls in raw water, runs it to a heat exchanger, the water accepts the waste heat from the engine, and that raw water is expelled through the exhaust. Do I have that correct?
If I'm having a problem with the manifold or riser, how exactly does that cause raw water to enter into the oil?

Thank you!!
Click to expand...
Exhaust systems that have lived their expected life span, should not be pushed past the limit, IMO.
If in salt water, this is of particular importance to us.

As for the first question, we probably need to know a bit more about your closed cooling system.
Is it a Full System, or a Half System.

But yes..... you have the basic understanding of the Heat Exchanger and the sea water's role in this, and that the "spent" sea water is directed out the exhaust.

However, until we/I know which system you have, we/I can't offer you a complete answer to the first part.

Nut shelling this..... if a raw water cooled exhaust manifold is compromized, it may introduce water into an exhaust port via what's called water reversion.
The water then gets past the piston rings, and ends up in our engine oil.
Other forms of damage may occur also.


Replacing exhaust manifolds is usally much less expensive than replacing an Engine.
.
 
Engine.jpg

This is out of my engine's manual. It looks like Full System to me.
 
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If your manifolds are fresh water cooled, they are most likely not the problem. Chief suspect for water in oil should be your exhaust risers and elbows, which are raw water cooled.
 
RMS said:
If your manifolds are fresh water cooled, they are most likely not the problem. Chief suspect for water in oil should be your exhaust risers and elbows, which are raw water cooled.
Click to expand...

Well that doesn't sound so bad, it's the cheapest and most accessible part.
 
Assuming you are doing the work yourself, be sure to get a manual to guide you on changing risers. You need to drain a couple gallons of antifreeze first. You may want/need to remove the exhaust hoses before attempting to remove the riser bolts. Also, if you need to pry the riser off the manifold, ensure you do not mar the manifold side of the manifold/riser mating surface. In general, be patient and resist the urge to use a large hammer to remove the riser.

BTW, another potential source of water in the oil is the oil cooler, although I have not experienced that particular failure. In my boating career, it's the risers and/or elbows that fail and dump the water internally.

Let us know how it goes. Bob
 
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