Loss of Coolant Problem

[Marc G]

I recently bought a 1987 Catalina 34 with the Universal M25XP engine. 
I replaced the weepy Sherwood sea water pump, and all the closed loop fresh water hoses except the water heater loop.
( Note, a good replacement for the FW pump hose is a NAPA Part number 11802 hose. UPC 0029769119570. mfg. by Gates. 90 degree bend, 1"ID x 3/4"ID.)

The engine runs quite well and the oil is not appearing contaminated in any manner.
However (caveat), I am loosing coolant, about a pint for every 5 hours of running time.

I have been unable to locate any sign of the coolant anywhere, which is scary.  I am concerned that it is going out through  the heat exchanger or some undisclosed or viewable component.

I would appreciate input for where to start peeling back the onion skin so to speak in search of the leak.
Any similar experiences or historical experiences?

Thank much,
Marc

[Ron Hill]

Marc : If you can't see/find any leaks then I'd remove the HX and have it cleaned and pressure tested.  You're not wasting $$ by having the HX pressure tested/cleaned, but eliminating a very possible leak source and 25 years later need to be cleaned anyway.

The next thing I'd have checked (if the HX is OK) is the head gasket.  Do a cylinder compression check first.

A few thoughts

[Marc G]

Thank you for the info Ron, I will check out the Hx.
How about the water heater as well. I could isolate it with a bypass loop at the engine and see what happens?

Marc

[Stu Jackson]

Welcome.

1.  Yes, the HX is always a usual suspect.  Most often, it turns out it isn't and is often the hoses to it and their connections.

2.  Water heater - yes, another one.  Harder to detect unless you put paper towels around it.  Again, check the connections.

3.  Then there's this:  http://c34.org/bbs/index.php/topic,3769.0.html

Good luck.

[Ed Shankle]

Wouldn't coolant show up in the bilge eventually if it was the HX or the heater?
If it's the hose, is the space under the sole large enough to hold a pint or two before it leeches out the hose holes and into the bilge?
I think another consideration is the exhaust manifold gasket. As I recall, there is a relatively narrow strip between the exhaust side the coolant side of the manifold. If that wasn't fully sealed, it could be passing coolant out the exhaust, as it would if the head gasket was shot.

Ed

[Ron Hill]

Guys : Ed brings up a good point on the gasket between the engine and the exhaust flange, especially if you just change your exhaust riser. 

I've always found it very beneficial to cut a fuel diaper and put it under the engine.  The drips on it will tell you all kind of thing by their color!!

A few thoughts