Salt Water Cooling System failure.

[rclampitt]

Recently purchased a Cal 31 Sloop with 16 hp Universal with fresh water cooling through a heat exchanger and salt water system. Subsequently sailed her offshore from Bellingham WA to Seward Alaska last month,1458 km. During voyage saltwater cooling system would fail in moderately rough seas and when pushed to over 5 knots. Have throughly checked impeller, hoses, and all connections. Opinions from various mechanics suggest pinhole leak in strainer gasket or hoses , to strainer too high above water line. No leaks apparent.

Any thoughts on this.

[WHOOSH]

R, I think you need to say what you mean by "...saltwater cooling system would fail in moderately rough seas and when pushed to over 5 knots." Fail in what way? Reduction in raw water discharge? Or do you simply mean the engine running hot, which points to the entire cooling system?

Suggestion: pull the end of the heat exchanger off (it should be a cap, sealed onto the end with a nut) where the raw water enters from the raw water pump. There may be debris there - weed, small pieces of impellar blade, etc. that restricts flow. Also, run a thin (1/8") but preferably rigid wire down each of the heat exchanger tubes - a piece of stainless or bronze welding rod is perfect for this, and cheap if you must buy it. If those passages are blocked, you''ll soon know it, tho'' that''s one of the first things a mechanic would have checked.

Jack

[rclampitt]

What I should have said is, "the salt water flow through the exhaust would abruptly totally stop". Ocasionally, would start again, without shutting engine down, within a minute or so, before overheating. Usually would have to slow the boat and restart the engine which usually worked. In one case, had to fill the salt water strainer to get a flow. Acts as though air gets in from turbulence, although no reported previous history of this. Will check heat exchanger as suggested. Also intend to conduct pressure test.

[WHOOSH]

R:

Check your thru-hull, from the outside. Does it have a grill that''s perhaps fouled with growth or a baggie (more likely) which flaps back & forth when the boat is underway, sometimes blocking the intake?

If hopping in the water with a mask isn''t an option for you, pull the hose off the thru-hull and then open the valve. Be prepared to stick something thru the thru-hull to temporarily clear it until you can get at it from the outside.

Have you pulled off the raw water pump (not just the impellar) and checked the face plate (too much wear for the impellar to be efficient) and keyway? Could it be slipping?

I think checking the heat exchanger is still a good idea. And now that we know it''s an issue or raw water flow, you need to check all the hoses in sequence, too. A pressure test won''t show a partial blockage.

Good luck. Just keep muttering ''this is boating; this is fun''. <g>

Jack

[rclampitt]

My wife and I did an overnight cruise this weekend and pushed to force a failure of the salt water system. Results. NO FAILURE UNDER ANY CONDITIONS WHICH PREVIOULY CAUSED FAILURE. I''m going to learn to love intermittant problems. Gremlins too.
R