Obstructed Heat Exchanger Outlet

BRMarshall

Active Member
Jun 5, 2012
40
0
Katy, TX
I noticed steam wisping from just one of the 2 exhaust ports at cruising speed. When I got the boat on the trailer and ran it on the hose, I noticed that one of the riser and exhaust hose was running hotter than the other. I disconnected the raw water hoses connected at the top of the heat exchanger raw water outlet. The tubing on the heat exchanger outlet forms a "Tee" with one connection for each exhaust riser hose. I found what appeared to be a rock partially obstructing the heat exchanger outlet (1" tubing "Tee"). The obstruction was on one side of the "Tee" which happened to connect to the hotter running manifold. I tried to remove the obstruction but the object was hard and was lodged in there. I tried to pry it out but it ended up falling back down the tubing, possibly back into the heat exchanger.

I'm thinking I need to somehow open the exchanger and clean it out? Any thoughts or suggestions on this one? Does it make sense that something that hard would be floating around in the heat exchanger? PS. Yes, the strainer is installed on the raw water intake.

Thanks!
 

redneck

Well-Known Member
Mar 2, 2009
1,453
59
Palm Bay FL
Is it an old piece of the pencil zinc that broke off? Mine has one installed in the heat exchanger not sure about the Indmar.
 

BRMarshall

Active Member
Jun 5, 2012
40
0
Katy, TX
Thanks fellas..............I've got the Indmar 351 heat exchanger. Any advice or caution for taking off and replacing that end cap? Hopefully it's straight forward.........
 

petertr3

Well-Known Member
Supporting Captain
Jul 11, 2017
337
38
Most heat exchangers are made by SenDure. If it has a single bolt in the center of the cap, be careful not to overtighten it when you reassemble. They are soft brass and deform easily. You can get the torque spec from Indmar or SenDure if it's not on instructions with the gasket. It's probably surprisingly low.
 

Fish Hunter

Well-Known Member
Apr 14, 2003
827
7
Brick, New Jersey, Barnegat Bay
I'm taking my heat exchanger off this winter.
First, a weld broke that was holding a mounting bracket. Second, it hasn't been cleaned in years. There's a radiator shop near me that cleans heat exchangers out, repairs any leaks and replaces the end cap gasket.
 

cw.abeljr

Well-Known Member
Jun 6, 2014
1,325
74
Pasadena, Md
If it's brass, you can clean it yourself with a bucket & some muriatic acid. Did the ones on my 6-71's for years that way.

+1 on muriatic acid.....You can get it at most swimming pool supply houses. It is used for cleaning the corrosion out of pool filter fingers. Nothing to do but soak it and then hose out good with fresh water.
 


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