Disappearing coolant on a AQ131,2.3 liter Volvo Penta engine

H

harrier

Cadet
Joined
Jun 24, 2012
Messages
6
Hi
When I got my 1986 Bayliner,with an AQ 131,2.3 liter engine ready for use this spring I noticed that the coolant was gone. I could not see it at the bottom of the hull. It had been sitting for 4 months after I winterized it. I refilled the coolant and checked two weeks later before I used it. Again it had leaked out and I saw it at the bottom of the hull. The lost of coolant has only occurred before the engine has been used.

Again I refilled the coolant and took the boat out for the first time this season. I have put 8 hours on the boat in the last three weeks and between use I have lost no coolant. I suspect some seal is going bad. I cannot spot where the leak is came from. The obvious places such as hoses show no leaking.

Are there seals with the sea pump that could be going bad? Are there gaskets with the impeller that could be going bad? It appears that some sort of seal has swollen with using the boat and no lost of coolant is taking place between uses.

Any suggestions?

Thanks,
Harrier
 
M

Maclin

Admiral
Joined
May 27, 2007
Messages
6,761
Re: Disappearing coolant on a AQ131,2.3 liter Volvo Penta engine

There are 2 chambers in the heat exchanger. The outside one circulates the raw water thru to cool the inside chamber which has the antifreeze and gets circulated thru the engine's cooling system. If the inside chamber leaks pressure then the antifreeze exits along with the raw water, no evidence, like the perfect crime almost.

That pressure check will tell you if the engine's cooling system and that inside chamber can hold the required pressure, good first troubleshooting step.
 
H

harrier

Cadet
Joined
Jun 24, 2012
Messages
6
Re: Disappearing coolant on a AQ131,2.3 liter Volvo Penta engine

Maclin said:
There are 2 chambers in the heat exchanger. The outside one circulates the raw water thru to cool the inside chamber which has the antifreeze and gets circulated thru the engine's cooling system. If the inside chamber leaks pressure then the antifreeze exits along with the raw water, no evidence, like the perfect crime almost.

That pressure check will tell you if the engine's cooling system and that inside chamber can hold the required pressure, good first troubleshooting step.
Click to expand...

Thank-you for the suggestion.

The pressure checks ok. If there was a pressure leak would the radiator cap be defective? Do you think the circulating pump seals might be going bad? The circulating pump itself? Would it be advisable to use an additive like a radiator anti-rust & water pump lubricant in the cooling system? Would that hurt?

Thanks,

Harrier
 
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