Leaking Heat exchanger cap Westerbeke 30B3

P

Pinch

.
Mar 30, 2009
23
Beneteau 361 Lottsburg, VA
Hi all

My 2000 Ben361 has a Westerbeke 30B3 with about 1200 hrs. All running great but have persistent leaking around the "radiator cap" on the heat exchanger. I've replaced the cap with Westerbeke's authorized part (14lb pressure cap) three times in past year, but to no avail. I've also carefully cleaned the mating surfaces and checked the seals on the cap - all look fine. I can see no cracks in the heat exchanger at or around the fill port.

Anyone else seen this issue - any recommendations on next steps to take?Thanks
Pinch
 
Maine Sail

Maine Sail

.
Feb 6, 1998
11,676
Canadian Sailcraft 36T Casco Bay, ME
Pinch said:
Hi all

My 2000 Ben361 has a Westerbeke 30B3 with about 1200 hrs. All running great but have persistent leaking around the "radiator cap" on the heat exchanger. I've replaced the cap with Westerbeke's authorized part (14lb pressure cap) three times in past year, but to no avail. I've also carefully cleaned the mating surfaces and checked the seals on the cap - all look fine. I can see no cracks in the heat exchanger at or around the fill port.

Anyone else seen this issue - any recommendations on next steps to take?Thanks
Pinch
Click to expand

Is your antifreeze getting diluted? You may have a pin hole leak in your water heater HX... Check/test the oil and check/test the AF... Sounds like you are exceeding the 14 pounds..
 
P

Pinch

.
Mar 30, 2009
23
Beneteau 361 Lottsburg, VA
Maine Sail said:
Is your antifreeze getting diluted? You may have a pin hole leak in your water heater HX... Check/test the oil and check/test the AF... Sounds like you are exceeding the 14 pounds..
Click to expand
No water in oil nor diluted AF - both appear normal. How would I be exceeding 14 lbs ?
Thanks, Pinch
 
centerline

centerline

.
Mar 20, 2012
3,983
Cal 34-III, MacGregor 25 Salem, Oregon
Pinch said:
Hi all

My 2000 Ben361 has a Westerbeke 30B3 with about 1200 hrs. All running great but have persistent leaking around the "radiator cap" on the heat exchanger. I've replaced the cap with Westerbeke's authorized part (14lb pressure cap) three times in past year, but to no avail. I've also carefully cleaned the mating surfaces and checked the seals on the cap - all look fine. I can see no cracks in the heat exchanger at or around the fill port.

Anyone else seen this issue - any recommendations on next steps to take?Thanks
Pinch
Click to expand
Is the system fitted with a coolant recovery tank?...
If it is not, then it would be normal for the system to purge itself of excess fluid as it expands while the engine is running.there would come a point where all the necessary headspace in the tank would be created and it would no longer leak... this space is usually about 1.5 to 2 inches below the filler neck.
Then whenever you see the coolant level low like this, its normal to want to top it off.. then the leaking begins again until the necessary headspace is created again.. so dont top it off. Leave some headspace

If you do have a recovery tank, headspace is not required or desired. considering what you have done already, its almost certain the filler neck has cracked loose from the tank and will need to be resoldered..

As MAINE SAIL suggested, if you.have a pinhole in the heat exchanger, as the engine cools from its previous use, it could suck seawater into the coolant chamber thru the pinhole.... then as the engine comes to temperature again on the next startup, it could cause the water to expand so rapidly as to force it out of the cap...

A system without a recovery tank NEEDS headspace... without it the system can definitley be overpressurized if the water heats up over 100 degrees.
 
D

Donnybrook

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Apr 2, 2011
185
Catalina 27 Niceville, FL
Technically, the fill cap is on the exhaust manifold, not heat exchanger. The neck is brass and the manifold is cast iron. They have been known to leak at the solder joint. Mine did and I found a few others that have had the same problem. I cleaned mine up good with a Dremel and a wire wheel. Then applied JB Weld over the seam. One year later, no leak.
 
P

Pinch

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Mar 30, 2009
23
Beneteau 361 Lottsburg, VA
Thanks for thoughtful comments Centerline and Donnybrook.
Yes, I have a recovery tank and it's mounted on engine compartment wall above the level of fill cap (yes, on exhaust manifold) as WB manual indicates. I have rarely added coolant over the years - the leakage hasn't required very much replacement. Although I have not visually identified any cracks at the filler neck, I'm now suspecting that may be the culprit - so I guess JB Weld is worth a try. Sure beats thoughts of removal and radiator shop repair. However that latter approach would enable a pressure testing to confirm leak source.

BTW, do you think an ordinary auto shop radiator pressure tester would provide the same info for me without removal of exhaust manifold???
Thanks, Pinch
 
D

Donnybrook

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Apr 2, 2011
185
Catalina 27 Niceville, FL
Pinch, my leak was easy to see. I think you can borrow or rent a coolant system tester from AutoZone or Advance Auto. Mine leaked at one place, but I sealed all around the neck. And yes, it would be a lot of work to remove the exhaust manifold, at least on my boat. The good news is that if the JBWeld did not hold, it should not wreck your engine. Since it is on top, it would only leak coolant until the level dropped. It would not pressurize, however.
 
P

Pinch

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Mar 30, 2009
23
Beneteau 361 Lottsburg, VA
Thanks, Donnybrook - will report results in a week, I hope
Pinch
 
jlp0217

jlp0217

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Jun 27, 2014
117
Jeanneau Moorings International 50 Everett
Could also be that the tube to the recovery tank is blocked - then the cap would leak to relieve the pressure buildup just like no recovery tank.
 
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