Can't find the leak

Jun 9, 2014
4
Catalina 38 Tiburon
Help, I own a 1984 Catalina 38 #274 with a Universal M-30 5425 engine. Months ago we overheated, the shop I was in replaced the raw water pump but the leak continued. Further research showed the leak was coolant. So long story short we have replaced the fresh water pump, thermostat, cleaned and pressure tested the heat exchanger ( radiator shop), pulled the front plate from the engine and replaced all gaskets and O rings but still have a coolant leak from the area near the alternator bracket. We have checked all cooling system hoses and have found nothing. Any help or suggestions would be appreciated.
 
Jun 9, 2014
4
Catalina 38 Tiburon
Help, I own a 1984 Catalina 38 #274 with a Universal M-30 5425 engine. Months ago we overheated, the shop I was in replaced the raw water pump but the leak continued. Further research showed the leak was coolant. So long story short we have replaced the fresh water pump, thermostat, cleaned and pressure tested the heat exchanger ( radiator shop), pulled the front plate from the engine and replaced all gaskets and O rings but still have a coolant leak from the area near the alternator bracket. We have checked all cooling system hoses and have found nothing. Any help or suggestions would be appreciated.
Oops, 5424 engine
 

dmax

.
Jul 29, 2018
971
O'Day 35 Buzzards Bay
Check the radiator cap. A good way to find a leak is to clean up the area completely, do whatever it is to make it leak some (run the motor, wait for some time to pass etc.) and then, starting from the top, dab clean paper towels over suspect areas and see if any coolant is picked up.
 
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Jan 7, 2011
4,727
Oday 322 East Chicago, IN
I had a problem like that on my old Yanmar 2GM20F…AF level would drop, but I could never find where it was leaking.
I was beginning to worry it was a bad head gasket or something.

I repaired a sketchy-looking cap neck, and tightened every hose clamp I could find on that engine…

…and I am happy to say that no more AF leak. Never did find a leak though.

Greg
 
May 24, 2004
7,129
CC 30 South Florida
They are not easy to find, best way is to clean the engine thoroughly and inspect frequently after that. I'm always wary of hoses and clamps as the seal tends to deteriorate with time. Hoses stretch, loose their elasticity and their grip on the barbs to the point where periodic tightening of the does not create that good seal. Of course after an overheating the gaskets become suspects. You can have the system pressure checked and see for how long the system remains pressurized indicating the magnitude of the leak.
 
May 20, 2016
3,014
Catalina 36 MK1 94 Everett, WA
When I had an oil leak I couldn’t find - I bought some fluorescent dye and a black light from Amazon for ~$30 - found the leak right off.
Given where you found it I would suspect either the line from the fresh water pump to the HE. Or the overflow/cap.