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Help! Leaking coolant cap on M40.

lnill

Member III
This is a classic "if it ain't broke" story. I had an old Stant radiator cap which I took into an auto parts store to get a replacement. I figured since I was cleaning the heat exchanger etc, might as well replace the cap. Have been losing coolant ever since through a steady drip drip drip as the engine comes to temperature. So I went to Hansen Marine and got a cap from them. It is Westerbeke part number 024306. I have also scrubbed the surfaces of the cap opening with scotchbrite to make sure there is no rough surface or corrosion. Still leaks. Any ideas?
Lee
 
Last edited:

lnill

Member III
Update

This is a classic "if it ain't broke" story. I had an old Stant radiator cap which I took into an auto parts store to get a replacement. I figured since I was cleaning the heat exchanger etc, might as well replace the cap. Have been losing coolant ever since through a steady drip drip drip as the engine comes to temperature. So I went to Hansen Marine and got a cap from them. It is Westerbeke part number 024306. I have also scrubbed the surfaces of the cap opening with scotchbrite to make sure there is no rough surface or corrosion. Still leaks. Any ideas?
Lee
I see no response so will post an update. I guess I was not patient enough. When I observed the leakage I put a diaper of paper towels around the cap. An hour later I checked the diaper and it was yellow but not very wet. Subsequently I found no leakage. So I guess the cap just needed a heat cycle to seat itself.
 

toddster

Curator of Broken Parts
Blogs Author
Some radiator caps are "double action" meant to release fluid to an overflow reservoir, then let it flow back in as the system cools. Some are single-action - just hold pressure in until they reach their set limit. If you have a spout on the neck of your heat exchanger, you are meant to have an overflow tank attached. Otherwise, you'll loose fluid to the bilge on every run.

It's important to buy the right kind of cap and also to get one with the right pressure setting for your system.
 

lnill

Member III
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