Loosing coolant ??

[bob_deb]

Hi,
I recently purchased a Pearson 323 that has a Volvo MD11-c
23 HP. I am loosing coolant, can't find any leaks, nothing in bildge or under motor, and oil looks clean. I am loosing about a quart every 6 hours of running time. Could this be in the Heat Exchanger ??? and could the coolant be going out the exhaust. Now the big question, Will this be something I can fix or should I call a mechanic ??
Next, When under sail, I can hear what sounds like my prop spinning ?
Is this normal or can it be stopped, I have never heard this on other boats.
Thanks, new boat owner - Bob & Deb

[Pblais]

Could this be in the Heat Exchanger ?

Could be or maybe worse. The coolant circulates so could leak at most any place it should not. Until you really find the leak you'll not know what to fix let alone how to fix it. If you knew for sure the exchanger was the problem replacing one isn't rocket science. A quart every 6 hours won't be going away on it's own and it is not normal to lose coolant. I won't say you never should lose coolant but you rarely need to add it even if you do check it regularly. You surely have a leak.

When under sail, I can hear what sounds like my prop spinning ?

If you don't leave the engine in gear it should spin. This may be not such a good idea depending on your transmission setup. Some prefer you to leave the boat in gear and in reverse when under sail. I'm sure this is not related to the leaking coolant. We have many posts on "freewheeling" propellers.

[SkiprJohn]

Aloha Bob and Deb,
There have been a few threads about loosing coolant too. Paul is right about needing to find the leak. What color is your exhaust? Does it feel or look like coolant is coming out your exhaust? The easiest to fix would be a leaky heat exchanger but I'm not familiar with your engine's setup so you'll need to describe exhaust to us. Look up some other threads on coolant, heat exhanger, or similar subjects.
JohnL

[44'cruisingcat]

I would try a new pressure cap on the cooling system first. It's cheap and it's worth a shot. I had similar coolant losses happening, and that fixed mine. An expansion bottle is a good idea too, if the boat doesn't already have one.

[hellosailor]

"I would try a new pressure cap on the cooling system first."
Assuming the pressure cap was bad, losing that much coolant could be confirmed by simply placing some paper toweling around/under the cap and looking for the rather gross signs of the leak. No need for a new pressure cap to check that. You'd be lucky if it was only a pressure cap--they're supposed to be replaced every so often anyway.<G>
If there are no signs of leakage IN the boat, then the coolant is probably going out the heat exchanger or the head gasket. (I say "probably" because I don't know that engine, it is possible there are other ways it could go out the exhaust.) The heat exchanger would be a relatively simple repair, the head gasket a bigger problem.
There's probably a way to pressure test the heat exchanger, to see if that is where the leak is. There are pressure gauges that can replace the pressure cap, not cheap but any real good auto parts shop would have them, and some might rent them. You'd pump up the pressure in the system (cold) and see if it held. If it leaked down, you'd know there was a pressure leak in the system. The catch is, it might only be leaking when it is hot, and that's harder to catch since the pressure will come down as it cools anyway.
If you run the engine (with the gauge on) and the pressure goes up, then falls off, that would be a sign of a leak opening up when it is hot.

[44'cruisingcat]

I'd still try one. It's about a $10 investment, and if it doesn't fix it, you've got yourself a spare. Like I said, i was losing coolant at a similar rate, and a new cap fixed mine. The "old" cap wasn't all that old either.

The water wont neccessarily leak out as liquid water - the pressure cap is there to raise the boiling point of the water - if it isn't maintaining pressure, the coolant could be leaking out in vapour form.

[hellosailor]

"if it isn't maintaining pressure, the coolant could be leaking out in vapour form."
Not vapor really, but steam. And the steam will still leave you with a damp and stained paper towel around the cap, betraying its passage. Paper towels? Probably already on the boat. New pressure cap? Gotta make a trip and hope they've got the right one in the store. I hate making those trips.[g]

[44'cruisingcat]

I'm not going to argue with you. I was losing coolant. I could have tried all kinds of other tests, but first I just replaced the pressure cap. IMHO it was the easiest thing to do. And it fixed the problem.

[bob_deb]

Thanks to all of you !!!
I am heading out today to find a pressure cap. I'll keep you all posted with the outcome, and I'll be back with more questions.
I have a list. ? ! ?
Thanks to all - Bob

[Boracay]

On my late, but not lamented, Ford 2402E I had to go over the engine with a screwdriver tightening (and sometimes replacing) all of the hose clamps.

If you do this you might see signs of seepage where the coolant has escaped.

The other "trick" was to clean up the engine and surrounds as much as possible and then to look for coolant leaks, drips and remains after the engine had run for a while. The coolant does have a distinctive appearance and smell.

If your coolant is not escaping into the boat then I would carefully inspect the engine looking for corrosion.

As to whether you should try to fix it yourself or to call a mechanic that depends on how good a mechanic you are.

I spent a surprisingly large amount of money trying to fix what was (despite surveyors and mechanics opinions) a useless piece of junk.

If the engine is old and has obscure problems it could well be cheaper to plan on repowering.

Depending on your situation it could be worthwhile to take the risk (factor in accidents, time, cost - tools, parts, facilities ) and remove the heat exchanger (or whatever major surgery is required) yourself. Check that you can get spare parts (gaskets etc.) beforehand and how much they cost (it is a Volvo...).

There is nothing quite as educational as fixing an old engine....

If your sailing does not depend on a reliable engine then it could be economic to use the engine until it kaputs.

[AnchorageGuy]

If you see no fluid then hellosailor is probably correct that the coolant is going out the exhaust through a hole in the heat exchanger. They deteriorate from withing after time and this is a common problem. After you try your new cap, pull the exchanger and take it to a radiator shop for testing.

[hellosailor]

Come to think of it...there should be a protective anode (a zinc) of some kind in the heat exchanger. Might just look like a large nut in the middle of noplace, like a domestic hot water heater would have, with a "rod" of anode extending from it.

If you can locate the anode--and find that there's nothing left of it--then a leak would be predictable.

[44'cruisingcat]

Originally Posted by hellosailor

"if it isn't maintaining pressure, the coolant could be leaking out in vapour form."
Not vapor really, but steam.

Not unless the coolant is boiling. Steam is water at 100'C + . (Assuming the boat is operating at sea level) Otherwise it's water vapour.

[never monday]

Pressure test the cooling system. If it leaks down there is a problem.

Most commonly the heat exchanger. The coolant rises to around 15psi and the raw water is at less than 5psi. the coolant will travel from high to low pressure.
Also possible is the head gasket. Your engine is 20+ years old. And finally there is the slim possibility of a cracked head.

[David M]

Originally Posted by never monday

Pressure test the cooling system. If it leaks down there is a problem.

Most commonly the heat exchanger. The coolant rises to around 15psi and the raw water is at less than 5psi. the coolant will travel from high to low pressure.
Also possible is the head gasket. Your engine is 20+ years old. And finally there is the slim possibility of a cracked head.

..or a head gasket that is leaking coolant into a cylinder.

There is also the possibility of the coolant pump seal being blown. This is pretty common when the bearing wears out.