Heat Exchanger

On Chevy 454's one engine is pumping more water than the other. Temps about the same but the one pumping less runs 10-15 degree's hotter, both run under 150, would like a little hotter but can not get them there. Changed impellors in raw water pump no change. Now looking at cleaning heat exchanger. How is this done, do you soak in something, do they come a part etc. The ones I have look like a U

If you can get it off, take it to a radiator shop for cleaning.

no they don't come apart. You can descale them yourself or send it out to get done. We sent ours out.

I have it off so just take it to a radiator shop and they will clean it.


THANKS

You said one pumps more than the other

I'm guessing you have exhaust risers. The sea water flows through engine and transmission oil coolers first then on to your engine heat exchanger, from there it flows in most cases to your exhaust risers. Some fresh water boats use sea water to cool the exhaust manifold but most fresh water cooled boats do not. If you do not have a infrared thermometer, this is a good time to get one. Often agt some point a raw water pump impeller fails and small parts flow up into the oil cooler and partially block flow. After checking you sea strainer for blockage, and that the hose supplying the pump is not collapsing or coming apart internally, I would check your first oil cooler for blockage. If these are clear it is easy to check your engine heat exchanger by removing the end caps and rodding out the tubes. Sea water flows through the exposed tubes. From here the water normally travels to the exhaust risers, cooling the riser and then sprayed into the exhaust gasses. You should be able to hold your hand on the riser without getting burned. I think your heat exchanger is probably not your problem, my guess is a badly rusted exhaust riser or blockage at your first cooler.

As long as you have things apart, you might consider replacing the hoses involved now rather than later.

I saw a fellow on YouTube cleaning his in place. He had a bucket of muratic acid solution and a small pump. He tied output of pump to raw water inlet. He fed water output back to bucket. Turned it on and let the contraption run about four hours.

Does that sound like a good way to rescale the heat exchanger to you more experienced folks? If so, I may give it a try myself.

frgeorgeh said:

I saw a fellow on YouTube cleaning his in place. He had a bucket of muratic acid solution and a small pump. He tied output of pump to raw water inlet. He fed water output back to bucket. Turned it on and let the contraption run about four hours.

Does that sound like a good way to rescale the heat exchanger to you more experienced folks? If so, I may give it a try myself.

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It would be relatively easy to descale that way on ours. Even easier (on ours) would be to simply block off the raw water inlet (which is lower on the heat exchanger), gravity fill through the raw water outlet (higher on the HX) and let the stuff sit for 4 hours. Flush, done. Not much in the way of fittings, hoses, pump required.

This, after just flushing both of our engines, one using the pump method, one not.

Seemed to me the pump method would more useful for flushing the full system. In our case, that's sea strainer, raw water pump, fuel cooler, aftercooler, gear cooler, and heat exchanger. With the raw water pump impeller out, and with appropriate fittings and hoses, the pump method worked fine. It's more difficult to remove the impeller on the other engine, so I experimented with the fill-and-sit method, with equivalent results.

-Chris