Heat Exchanger

[JFrog]

Hey guys,
Ok, been trying to figure out how the heat exchanger works. How does the engine get cooled with both coolant and incoming water?
I'm wondering too because the cap that goes over the strainer broke off and I'd like to know why that cap is there and what would happen if I didn't have a cap. I really don't want to spend $175 to replace the housing just because the stupid cap broke off.
Thanks in advance,
Keith

 

[Bondo]

Re: Heat Exchanger

Hey guys,
Ok, been trying to figure out how the heat exchanger works. How does the engine get cooled with both coolant and incoming water?
I'm wondering too because the cap that goes over the strainer broke off and I'd like to know why that cap is there and what would happen if I didn't have a cap. I really don't want to spend $175 to replace the housing just because the stupid cap broke off.
Thanks in advance,
Keith

Ayuh,.... The motor is cooled by the coolant,...

The coolant is cooled by the raw water in the exchanger...

Ya need Both workin' properly or ya ain't goin' nowhere...

 

[captmello]

Re: Heat Exchanger

You don't mention what engine your working on, but I'll guess an aq125.

The cover for the strainer allows you to clean out the strainer periodically. Without the cover, i would expect water to be shooting out of the strainer housing. That would not be good for many reasons.

 

[JFrog]

Re: Heat Exchanger

Yeah, sorry guys, working on an AQ125B.

Ah, so instead of a radiator cooling the coolant, the raw water cools the coolant instead.

Shoot, I was afraid water might shoot out the top of that housing. Do you guys know if its under alot of pressure? I'm wondering if I could cover it by some other means.

 

[captmello]

Re: Heat Exchanger

So whats broken or missing? Personally, I prefer to fix things correctly.

There is a strong stream of raw water that flows into the strainer. It hits the side of the strainer and will spray all over. All the parts are available for your engine, not cheap, but available.

Maybe look on ebay, or call around. Those engines were very common and used parts are out there.

 

[JFrog]

Re: Heat Exchanger

The top of the strainer housing lip broke off so the housing cap no longer screws on. I saw that to replace the strainer housing it costs around $175! Alot of money for something so small. I completely agree with fixing things correctly, but crap! Ugh.
Anyway, thanks guys!

 

[captmello]

Re: Heat Exchanger

Sorry to say, $175 is nothing in the boating world. However, I agree its a lot of cash for the Budget Boater. I'd call around to some boat salvage yards/repair shops, try to find one used.

 

[JFrog]

Re: Heat Exchanger

Will do, thanks again guys!

 

[Don S]

Re: Heat Exchanger

The old Volvo 4 cyl engines are not the cheapest engine you can work on, they are one of the most expensive. Image how you will feel if that $1400 circulation pump fails No, the automotive version will not work.

 

[Alan Lloys]

Re: Heat Exchanger

The old Volvo 4 cyl engines are not the cheapest engine you can work on, they are one of the most expensive. Image how you will feel if that $1400 circulation pump fails No, the automotive version will not work.

This was the situation I had on the boat I bought. I came up with a method of modifying an automotive water pump to fit in without having to modify the heat exchanger. I have run with it without any problems for the last 1/2 of the season.
I am working on an improved version that I will likely offer for sale for around $ 250.
So if you have this problem please don't go down the expensive route.

On the strainer cap I do see the heat exchanger housing or just the strainer portion for sale on Ebay from time to time.
You cannot run it without the cover in place as it will fill you bilge quickly. When I first got the boat the cover was not tight enough and it was spraying a good amount of water.