Losing coolant

[DenisHeinrichs]

Twice now, I have gotten to my boat to notice that the coolant in the reservoir is severely depleted. This has happened twice over the last 2 months. I have topped it off and checked the levels between instances, but have not seen any drop in fluid.....


What could be causing this?


I have not seen any coolant in the bilge, or any obvious leaking. I did change the heat exchanger zinc the other day, but that should be on the salt water side of the system. There has not seemed to be any drops after the last couple of times I went out in the boat.


I have heard some rattling in the front of the engine, which could be the water pump, but not sure about that....again, no obvious signs of leaks.



I am going to do an oil change and see if the oil looks normal or has anything obvious in it.


My very uneducated guesses as to where it could be going is
a) overboard due to maybe a leak in the heat exchanger
b) into the oil pan due to an internal leak
c) into the bilge and I am just not seeing it
d) into the hot water tank due to a leak in its heat exchanger


Any other potential places, and how do I test the above?

Or am I missing something obvious (always a possibility)?

[Tillsbury]

I think you have the most obvious ones listed. If your engine bay is clean and your coolant green (or otherwise identifiable) you can discount hose leaks into the bilge. If your hot water isn't disgusting it's not going there.

That leaves the coolant temperature as your clue. Over temperature coolant (and milky oil in the engine) would suggest to me the leak is in the "engine" part of the engine. No unusual temperatures and clean oil suggest it's leaking into the salt water side of the heat exchanger.

[tkeithlu]

Thoroughly agreeing with Tillsbury, let me add:

A quick check of your dipstick will tell you if coolant is going into the engine oil. Coolant is 50% or better water, so you'd have a milkshake in your pan.

Overheating and over pressurizing the coolant should show in discharge out the side of the coolant cap - that makes quite a mess, so it doesn't sound likely.

I'm betting you've got a leak in the heat exchanger. It may only be showing up when the engine is hot and the cooling system pressurized.

[Shrew]

If you're loosing coolant and it isn't in the bilge, the most common location is pin holes in the heat exchanger. The closed cooling side is much higher pressure than the raw water side. When (not if) holes develop, the higher pressure of the closed cooling side causes the coolant to leak into the raw water side and get discharged out the exhaust. It's usually a very slow process.

[DenisHeinrichs]

Originally Posted by tkeithlu

Thoroughly agreeing with Tillsbury, let me add:

A quick check of your dipstick will tell you if coolant is going into the engine oil. Coolant is 50% or better water, so you'd have a milkshake in your pan.

Overheating and over pressurizing the coolant should show in discharge out the side of the coolant cap - that makes quite a mess, so it doesn't sound likely.

I'm betting you've got a leak in the heat exchanger. It may only be showing up when the engine is hot and the cooling system pressurized.

I agree that the heat exchanger sounds like the culprit. The thing that confuses me is that it has only shown up when the engine is cold and has been sitting for days (it has only happened twice). After running the engine for hours and checking over the next couple of weeks....no loss in coolant.

[DenisHeinrichs]

Here is an update:


I had the heat exchanger serviced. It was apparently really plugged but after the chemical bath to clean it....no leaks. It is actually in really good condition.....


Still stumped.....


I am going to go do a full oil change and see if there is anything noticable in the oil......

[deblen]

Suggest you purchase :


https://www.amazon.com/radiator-pres...ure+tester+kit

[Shrew]

Originally Posted by DenisHeinrichs

Here is an update:


I had the heat exchanger serviced. It was apparently really plugged but after the chemical bath to clean it....no leaks. It is actually in really good condition.....


Still stumped.....


I am going to go do a full oil change and see if there is anything noticable in the oil......

Check your oil and see if you 'grew' any oil over time.

[skipperpete]

How much coolant loss are we talking about here, 250ml? 2 litres.
Is it a small expansion tank or a big ol Volvo one??

[DenisHeinrichs]

I figure I lost about 2 litres on each occurance. The engine is a Ford Lehman 80.


I have put the newly service heat exchanger back on, and have also replaced the fresh water pump (shouldn't it be called coolant pump?) with the brand new spare that I have.

Tomorrow I will top up the coolant and hope for the best.

Ideally, I guess I should get a pressure tester and see if all is good, but I leave on the boat on Thursday for a couple of months up the BC coast.

[Wotname]

Originally Posted by DenisHeinrichs

I figure I lost about 2 litres on each occurance. The engine is a Ford Lehman 80.

.........

Some (many?) Lehmans have three heat exchangers - one for the coolant, one for the engine oil and one for the gearbox fluid.

Presumably you have checked all of them.

Can the coolant escape from the coolant cooled exhaust manifold and go down the exhaust?

[DenisHeinrichs]

Originally Posted by Wotname

Some (many?) Lehmans have three heat exchangers - one for the coolant, one for the engine oil and one for the gearbox fluid.

Presumably you have checked all of them.

Can the coolant escape from the coolant cooled exhaust manifold and go down the exhaust?

Only the main heat exchanger has coolant in it. The other two just use sea water.

[skipperpete]

AHA! Ford Lehman. That totally changes the game. The exhaust manifold is coolant cooled, and has a bleeder/vent on the front end plate and the mixer elbow on the other end.... both ends are sealed by gaskets to contain the coolant.
Pete.

[Wotname]

Originally Posted by DenisHeinrichs

Only the main heat exchanger has coolant in it. The other two just use sea water.