Is it possible to leak coolant from the raw water pump/engine block union?

PEMS

.
Oct 26, 2024
6
Catalina 310 175 Annapolis
I have a coolant leak on my m25xpb. My initial search pointed to the short elbow hose from the coolant pump, under the raw water pump. I replaced it, but I still have a leak. After watching for awhile it seems the drips are developing on the underside of the Sherwood raw water pump.
This doesn’t make any sense to me, unless there is a coolant jacket built into the block that is open behind the raw water pump? But I think that would have been mentioned in the various posts about changing the Sherwood pump out.
It is definitely a coolant leak - I see it in the engine bilge and the overflow tank is going down
I looked all around the belt driven coolant pump, thinking it was leaking and blowing coolant over to the Sherwood, but it is clean, including the area near its weep hole.
Any thoughts would be appreciated.
 
Mar 6, 2008
1,493
Catalina 1999 C36 MKII #1787 Coyote Point Marina, CA.
No, there is no path the antifreeze will leak out of the raw water pump.
When I am trying to locate the source of a leak, I clean the area then I place a paper towel where the leak is with engine off. Later remove the paper towel and see if it is dry.
Before cleaning, take a few photos and post here.
 

john2

.
Nov 26, 2022
101
Catalina 310 58 Leimuiden
if there is wet on/under the raw water pump , maybe replace that seal first.

the short pipe under the pump is also a good one to check.

our biggest coolant leak was the heat exchanger at the back of the engine... one of the loose brackets went through the housing.
 
Last edited:
Sep 29, 2008
1,969
Catalina 310 #185 Quantico
If it is Coolant the Sherwood (or Oberdorfer if you upgraded yours) is not the problem. There is a pump that moves the antifreeze around in the engine, but also right above where your raw water pump is the thermostat housing. Could that be the leak. FWIW the anti freeze and raw water are two separate systems that only meet at the heat exchanger. Try chasing the leak by following those hoses.