When to clean heat exchangers

I've been running a heat exchanger on my 350 Chevy/Merc for about 10 years now and was wondering what type of maintenance/cleaning these things need and how often. The motor was starting to run on the warmer side, but after looking at the exhaust manifolds condition, I figured it was probably the culprit. This system gets in the salt a fair amount every year.

So what's the story on H/Exchanger maintenance?

The user cannot easily access the E/G side of the tube bundle.
However, a radiator shop who is equipped to do Marine Heat Exchangers, can perform a complete assessment for you. They will be set up to take the unit apart and fully clean and/or repair it.

You may want to remove it, fill with hot water, shake the crap out of it, and then dump the contents into a white bucket.
Look for any rust scale debris that has not completely bonded to the tube bundle.
There is an acid wash that you can carefully use if you follow the instructions to the letter.


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Are there any early warnings of a problem coming up that I should be noticing?

The motor was starting to run on the warmer side...

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That's a first sign...how old is the impeller?

guyjg said:

That's a first sign...how old is the impeller?

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Replaced the complete pump last year. I try and do it every 2 years. Where will the problem most likely be, in the contained/antifreeze side in the tubes, the fresh water side or both? Would there be a problem with popping one of the sides off and taking a peak inside?

If it has been a number of years since the antifreeze was changed I would start w/a flush and refill. Pull the end caps off of the exchanger and take a look at the tubes. If there is a buildup if crud then do as Rick stated: "...a radiator shop who is equipped to do Marine Heat Exchangers, can perform a complete assessment for you. They will be set up to take the unit apart and fully clean and/or repair it." Doing it is part of boating PM. Verify the coolant circulating pump is not seeping out of the weep hole on the underside of the shaft housing. As soon as you flush the engine it will spring a leak.

I did take the caps off and was prepared to rod it out if need be, but it was clean as a whistle. The antifreeze was changed last year also. The old stuff looked fine. No crap in it of any kind.

kimcrwbr1 said:

Probably the best cleaner is easy off oven cleaner. drain it completely and plug one end of each side and then fill it with oven cleaner and let sit overnight flush it good with water and then do a leak check. If it leaks it needed to be replaced anyway. It works great for car radiators and heater cores also. Common household bleach applied the same works pretty good also just be careful when rinsing/draining the cleaner.

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In my unit, (which says 'San Juan Enterprises' on the end cap), when you take the end cap off, you're looking at maybe 50 or more 3/16 tubes that the raw water runs through from side to side and they are clean. When you speak of using the acid or such, are you talking about cleaning the other side of the tubes where the anti-freeze is?