Heat exchanger / repair or replace

Jaay757

Member
Jun 18, 2012
141
Buzzards Bay, Mass
Boat Info
2006 sea ray 340 sundancer (sold)
Engines
8.1's, ZF IV V drives
While winterizing I noticed my coolant reservoir tank was low. I refilled it and overnight I lost the coolant I added. I checked the end cap of the heat exchanger on the raw water side and located my missing coolant. So there is obviously a crack or break inside the exchanger on the coolant side to allow this. From what I can see inspecting from the end caps there does not appear to be any corrosion, however I can't inspect the whole unit. So my question is should I replace with new or take it to a radiator shop and try to have it fixed if it can be even done. I hate to put good money to bad, but spending $900 is killing me. Also has anyone used any of the aftermarket exchangers? I know there are a few out there. Any suggestions would be appreciated.
Thanks
Jason
 
While I've never had to replace one, I've been told that the exchangers on 8.1s are essentially throw away.

You can likely get a little longer out of it by having it repaired (they may just braze the tubes shut) but eventually the others will start to go.
 
Replace it with a aftermarket cooler.
I like the SeaKamp brand sold from Go2marine at decent prices.

Good luck,
 
Going through this right now. Took them to a radiator shop and they said to replace them. Parts just came in and my mechanic is installing this weekend.
 
Thanks guys looks like I'll be looking for a replacement.
Michael what did you use as a replacement OEM or aftermarket? I have looked at the seakamp and mrcool also offers one for a couple hundred dollars less.
 
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Thanks guys looks like I'll be looking for a replacement.
Michael what did you use as a replacement OEM or aftermarket? I have looked at the seakamp and mrcool also offers one for a couple hundred dollars less.

I believe we went OEM, but will verify this weekend for you.
 
I have had to replace both of mine - one two seasons ago and one at the beginning of this season. When I researched it the general consensus seemed to be that having them repaired may buy you a little more time but you were going to have to replace them in the end. I decided to go with just replacing them up front. The first one was OEM which I purchased from Performance Product Technologies (https://www.perfprotech.com/mercury-outboard-parts-mercury-outboard-motor-parts-diagrams) and the second was aftermarket from eBay. I've not had a problem with either ... but the real test will be how long they last! This was a very easy repair that I did myself ... I took a bunch of pics, I should put them in its own thread. I still have the old one sitting in the garage - was wondering how much all the copper would be worth if I take it to a recycler.
 
I've purchased engine oil coolers with MrCool products (in my previous boat). Top notch stuff. I just had to spray them Merc. Black. Your job is pretty easy - just plan on dumping a fair amount of coolant. Keep a shop vac handy to catch it. If the vac is clean you can put it back in.

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Great info, thanks guys, I already have the exchanger removed as I thought I would try to have it repaired while the boat was laid up, but that has since changed as I believe now I will just replace it.....
Thanks again
Jason
 
You'll want to replace the two rubber "seats" that the cooler sits on at the same time. The old ones get hard and start to leak during the winter when things tend to shrink...
 
You'll want to replace the two rubber "seats" that the cooler sits on at the same time. The old ones get hard and start to leak during the winter when things tend to shrink...

I'm trying to figure out what part you mean ??

Edit.......you must mean the end cap gaskets.
His new cooler should come assembled with new caps and gaskets installed.
At least my SeaKamp ones did.
 
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The cooler sits into 2 seals onto the top of a manifold on the 8.1's. #14
 

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The cooler sits into 2 seals onto the top of a manifold on the 8.1's. #14

I see....part # 26-865066 - SEAL - Heat Exchanger to Crossover. $11.31 each - 2 used.I'll have to look at that next time I'm working on an 8.1.

Thanks,
 
Question: so the coolant is in the heat exchanger, raw water side, is there a chance the raw water mixed with the FWC. I tested the antifreeze remaining in the manifold below the exchanger -20. I believe the pressure on the FWC side is higher than that on the RWC side which would not allow this but just wanted to get your thoughts. Those that changed out the exchangers did you also flush and refill the FWC.

Thanks
Jason
 
When one of mine leaked, the coolant was forced out of the system into the raw water side of the exchanger and went out the exhaust ports. It eventually drained the reservoir. I don't think raw water entered the coolant side...
 
Question: so the coolant is in the heat exchanger, raw water side, is there a chance the raw water mixed with the FWC.

When I read this I didn't understand the question. Still kinda don't. The coolant is in the heat exchanger- YES. Coolant does not run through the raw water side.

Can coolant leak into the raw water, and vice versa - YES. If the heat tubules are leaking.
 
Thanks Jim, Thats what I thought, that is what mine was doing also, however as it is laid up now for the winter I began to question myself if coolant could enter the raw water why not vice/versa. I did test what was left in the system and appeared to be coolant to -20.
Thanks
Jason
 
Reanimating a dead thread...
8.1s, port engine, coolant gone from the reservoir. it's not in the bilge and crankcase oil is clean. Need to replace the heat exchanger and would also like to take the opportunity to drain, flush and replace coolant in the fresh water side of the system. Manual says capacity is 20 quarts. How do you drain it all out? Is there a plug somewhere at the lowest point?
 

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