Volvo AQ125 Engine Cooling System

ebaytodd

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Jul 13, 2005
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As I understand it, the Volvo Penta AQ125 has 2 cooling systems. There is the fresh water system that by means of the impeller, draws water into the cooling system and discharges it thru the lower unit back to the lake. The 2nd system involves the antifreeze and the heat exchanger. <br />I assume that there are a system of tubes through out the engine that hold the antifreeze and deal the heat. As you can tell though, I am no mechanic. I have 2 problems with my cooling system. Water that has passed the impeller leaks out thru the cap on the fresh water strainer assembly. Is it common for there to be an obstruction in the line ? Could a mouse have taken up residence in the discharge pipe ? The leakage is not that bad but the possible combination of my 2 problems has lead to my operating temps to rise from 180 degrees to about 190. The 2nd problem involves the antifreeze. I can fill up the heat exchanger with antifreeze and it is all but gone after a day on the lake. The engine runs like a top ( I guess I should say that it ran smooth and steady for 8 hours of trolling last weekend with only 1 slight cough ) and I see no sign of antifreeze in the bilge area. Is this a sign of a cracked block? Where does the antifreeze go ? Is there a pet **** underneath that may be leaking ? Any advice would be a step in the right direction. THANKS
 

Don S

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Re: Volvo AQ125 Engine Cooling System

Water that has passed the impeller leaks out thru the cap on the fresh water strainer assembly.
That would be the raw water strainer. The fresh water is considered the antifreeze side.<br />Replace the cap.<br /><br />
Is it common for there to be an obstruction in the line ? Could a mouse have taken up residence in the discharge pipe ?
That wouldn't have been my first choice, but the leaky cap would be, as I said, replace the cap.<br /><br />
2 problems has lead to my operating temps to rise from 180 degrees to about 190
Those are normal temps for a 125.<br /><br />
I can fill up the heat exchanger with antifreeze and it is all but gone after a day on the lake.
Most likely a problem with the heat exchanger. The antifreeze side would have more pressure than the raw water side and a small hole in the heat exchanger would force the antifreeze out into the raw water stream.
 
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Re: Volvo AQ125 Engine Cooling System

DON S
I am having the same problem Thank you for your response on this issue. I have replaced my cap and all is well! Thanks again
 

FunkyLonnie

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Aug 7, 2008
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Re: Volvo AQ125 Engine Cooling System

i just got this boat a 1984 bayliner capri with a 4cyl volvo penta that has sat for 4yrs. i went through gave it a tune-up and the i took it out to the lake and it ran for a little while and got hot very fast . it wasnt picking up any fresh water from the lake so i was going through the system and found the impeller was bad son replaced with new. then i thought the problem would be solved so took out to the lake on fri nite and ran for a while and got hot again so while on the lake found the thermstat and it was stuck so removed and ran a little longer and still got hot where does it pick up water from the lake . also while running with the hood on it bogs it wont open up with the hood off it seem to get more air can anyone help me lonnie funk
 

jerryjerry05

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May 7, 2008
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Re: Volvo AQ125 Engine Cooling System

The water from the cap can come from 3 places .The cap,the manifold is bad or the brass heat exchanger is clogged.If you replaced the cap and impeller then the manifold is probably the culprit.
If the boat was ran in salt water then the brass exchanger could be clogging.
Remove the manny and check the end for corrosion.If it's clear. Then the exchanger can be removed and flushed with muriatic acid(don't let it set too long).
If your boat set for a long time then you probably need to clean the carb. Jerry
 

Don S

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Re: Volvo AQ125 Engine Cooling System

Best to start your own thread Funky lonnie, don't just hijack someone elses old post.

Who are you answering Jerry? The original poster or lonnie?
 

jerryjerry05

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Re: Volvo AQ125 Engine Cooling System

I wasn't paying attention to who posted what I was answeing both.Jerry
 
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