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Overheating issues

CaptJoe3 said:
The sherwood pump was overhauled using the major repair kit. Shafts were ok so not replaced, just cam, bearings, seals, wear plate. My mechanic has over 50 years experience in marine maintenance after his tour in USCG as "Engineman". Is a member of ABYC.
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Re: Clear hose. Mech. believes thee clear cap on strainer gives that info. Wants to try a clear hose "into a clear cylinder with "headspace"
 
The clear hose in the product side of the raw water pump isn't the same as the strainer...the "headspace" won't last long...but thats his choice..
 
makomark said:
i believe you...just trying to understand what was done vs what wasn't done...tnx!
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I wasn't getting testy. Both me and my mech are very frustrated and seeking any input towards something we may have missed or are not aware of. I appreciate your interest and knowledge. I'm the middleman! I'm relaying this stuff back and forth.
 
I've seen a few cooling issues where the pump was "rebuilt" and the reality was the impeller and gasket were changed...the wear parts were overdue ...and we know how that works.

What's unique is that the system appears to cool up to the 2200+/- RPM point and then goes hot...that suggests something changed and now to figure out what that is...the only things I can envision are a minor air leak that gets 'bad' at the RPM level change or (hopefully not) a minor combustion leak into the cooling system. they can be checked using a procedure with a clear overflow hose or test strip that finds the hydrocarbon residuals in the coolant.
 
makomark said:
I've seen a few cooling issues where the pump was "rebuilt" and the reality was the impeller and gasket were changed...the wear parts were overdue ...and we know how that works.

What's unique is that the system appears to cool up to the 2200+/- RPM point and then goes hot...that suggests something changed and now to figure out what that is...the only things I can envision are a minor air leak that gets 'bad' at the RPM level change or (hopefully not) a minor combustion leak into the cooling system. they can be checked using a procedure with a clear overflow hose or test strip that finds the hydrocarbon residuals in the coolant.
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We're going to take a run to get temp data at 2500 and 3500. Last resort I'm thinking of ordering a new heat exchanger. Nightmare would be pulling heads though there is no sign of water in oil. BTW, I've had four oil sample analyses since re-power. Most recent showed elevated bronze and higher fuel. Lab not worried but wants another sample in 20 hours. Happy to share with you.
 
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