Heat Exchanger

[rhythmsurfer]

Hey Ed,
On your heat exchanger does it have an outlet (aka burp tube) at the top where the fill cap is? If so where does it lead to? Mine is in the port lazarette next to the batteries and I want to mount it like yours in the picture you posted a while back. Mine did not come with a hose on the burp tube but I did put one on and connected it to a coolant reservoir that I purchased at an automotive store. Thanks for sharing all of your knowledge.

Tony

 

[rardiH36]

Hello RythmS:

I'll be at my boat tomorrow and will take a picture of the heat exchanger mounting on my 1980 H36 -- also in the port lazarette. It's a Send-ure 2550. Until then, a picture and a drawing of it, done five years ago are attached. (These from my archives done at the time that I brought the exchanger to a radiator shop that also specialized in marine heat exchangers. Mine had pinhole leakage between the salt and contained circuits. Fixed successfully -- so far -- for about 40% cost of a new one.)

As you have observed on yours, my purchase surveyor also noted the lack of connection between the over-flow port and anything. So I did as you are thinking and bought a reservoir from an auto store.

If you have the same engine as me, a 2QM20 that has been converted from seawater cooled (i.e. seawater coursing through the block) to an anti-freeze cooled engine with an externally mounted heat exchanger, one item to note is that the thermostat housing accepts only the 140F thermostat. Also, the coolant filler cap on my boat has a very low pressure trigger point. I did overheat my engine once due to forgetting to open the seacock. The extra high temp pressure on the cap did not cause the coolant to first go into the reservoir. Instead the cap vented steam and coolant into the lazerette rather than much into the reservoir. I feel better that I have the overflow tube and the reservoir. But I am not sure how much good it actually does.

 

[rhythmsurfer]

Sounds great. Last summer I restored my heat exchanger. I used muriatic acid and it did a fantastic job of cleaning the tiny tubes inside. I don't like the set up I have now. The plastic jug/container for the overflow had a leak in the seam so I took it off. I just don't like the batteries being under plumbing. Thanks for your response.

 

[rardiH36]

Dear RythmSurfr:

Took a couple of pic's. Not the prettiest part of my boat. Wires and tubes aren't aligned in any consistent direction. Shows my heat exchanger location in the port lazerette. My guess this was the original Hunter location. Picture was taken from the aft side looking forward, so the engine compartment is to the right. When I bought my boat, one of the batteries was under the exchanger strapped onto to the interior liner floor.. I didn't like it there so I moved it next to the other one on the battery shelf. But the space was occupied by the refrigerator compressor. It wasn't working so I tucked the compressor out of sight. You can see it behind the over-flow tank. Eventually, if I ever do decide to start using my boat for a living space for more than a a couple/three nights, I will disconnect the compressor and ask an expert to determine if worth repairing. But I expect I will instead find a way to tuck a more modern Dometic type refrigerator/freezer somewhere in the galley area rather than restore the original cold locker.

I have thought about moving the heat exchanger into the engine compartment. But that makes removing the pressure cap to check the coolant level and also adding new coolant much more of a task.

 

[Ed Schenck]

I am really surprised at how these installations were done. I no longer have the 2QM20 but kept the pictures. As you can see the heat exchanger was mounted on the engine.

 

[rhythmsurfer]

Well I am still unsure of what to do. I would think that you wouldn't need to inspect it. If you were loosing coolant I would think it would show up in the bilge. After looking more closely at the system yesterday I noticed one of the coolant hoses had a nick in it where the "big round disc" (unsure of the name) attached to the drive shaft rubbed it. I don't think that would have happened if the heat exchanger was attached to the engine. The hoses are just too long and don't give a neat look. Not to mention I don't have any compartment/walls around the engine. I will let you guys know. I have to think about it some more.