Heat exchanger

Jan 22, 2008
55
Hunter 376 Point Roberts
I am looking at removing and cleaning the tube out of my heat exchanger on my Yanmar 3JH2E.
If I open only one side only, probably the front cover plate...will the tube slide out? The back of the heat exchanger access is not very good with the mixing elbow in the way.
 
Nov 6, 2006
9,884
Hunter 34 Mandeville Louisiana
Yes, the tube bundle will slide out but you will not be able to get it back in correctly without removing the back cover to get the gasket and o-ring replaced..
go ahead and remove the elbow manifold and the back cover or you'll do it after the fact..
Good luck with it..
 

SG

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Feb 11, 2017
1,670
J/Boat J/160 Annapolis
Don't waste your time with chemicals, they won't work or worse. When you get it out, send it to the radiator shop. I've had my tubes cleaned 4 times in 20'years on our Yannmar. We have well ove 2,500 hours on the engine. (I'm not sure sitting in an airport, how many ;^))) )
 

Johnb

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Jan 22, 2008
1,419
Hunter 37-cutter Richmond CA
I advocate going over the whole raw water loop - sea cock, strainer, pump, heat exchanger, exhaust manifold, mixing elbow, zincs and maybe connecting hoses while you are at it. There was another thread just recently about this, recommend you look it up.
 

SG

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Feb 11, 2017
1,670
J/Boat J/160 Annapolis
Good point on looking at the system. However, the Yannmar doesn’t have zincs. The manifold usually isn’t an issue? The mixing elbow is clearly something to check. The hoses should be easy to inspect along with the clamps.
 

Johnb

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Jan 22, 2008
1,419
Hunter 37-cutter Richmond CA
I once had a problem (way up in the Petaluma river - no way to sail out of it) with crud packed in right where the raw water exits from the exhaust manifold and have made it part of my maintenance ever since.

FWIW I found that it is quite easy to blow through the heat exchanger, exhaust manifold and mixing elbow when they are clear and with a bit of luck this can be used to locate a problem. It is amazing how clogged the raw water system has to be before you get a noticeable malfunction.

I have a 3QM which does have a zinc in the heat exchanger.
 

SG

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Feb 11, 2017
1,670
J/Boat J/160 Annapolis
Do you have a strainer on the intake? Even with one, I’ve heard stories of people going aground in a mucky bottom with Fines that got stirred up by the efforts to get free.
 
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MitchM

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Jan 20, 2005
1,009
Nauticat 321 pilothouse 32 Erie PA
you'll need the peculiar yanmar replacement gaskets for this ht exc unless you are extremely good and patient with form-a-gasket from the auto store. the 1st time took off the end caps to clean my ht ex for an emergency repair on the water, the oem gaskets got damaged beyond repair.
 

Johnb

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Jan 22, 2008
1,419
Hunter 37-cutter Richmond CA
The strainer is sized to hold back anything too big to go all the way through.
 
Feb 16, 2019
7
Catalina 350 Oriental nc
On a somewhat related question ... I have read a recommendation to check the zinc on the heat exchanger monthly. Looks like a bolt to simple remove and examine. If removed to check will a large quantity of coolant drain out of there ?? tx ...
 

AlexB

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Aug 9, 2016
37
C&C 36 Great Kills harbor.
On a somewhat related question ... I have read a recommendation to check the zinc on the heat exchanger monthly. Looks like a bolt to simple remove and examine. If removed to check will a large quantity of coolant drain out of there ?? tx ...
There is no coolant on raw water side of system.
 
Dec 14, 2016
3
Hunter 340 Venice
I have the 3GM30F. Definitely check the mixing elbow when it is removed. I usually get only 3 years before it or the threaded coupling needs to be replaced, and clean out the heat exchanger tubes at the same time. If the mixing elbow or its coupling fails, it is not a pretty sight and makes a big mess with raw water spraying down on the engine. The week point is the treaded nipple. It is thin to begin with and will usually fail first.