Heat exchanger clogged.

[jstaff]

I discovered that the raw water inlet of my heat exchanger was becoming blocked. There doesn't seem to be many posts on the subject so it doesn't seem to be a common problem. I'm assuming that it's a calcium deposit.

After winterizing the engine I'm planning on removing the heat exchanger and circulating an acid through it using a small pump. I'd prefer this over possibly recirculating debris through my MMI raw water pump.

I'll also renew the gaskets/seals on the end caps...

As an alternative, would it be better to take the cooler to a radiator shop and have them clean it?

Does anyone have experience with this?

Joe

[Dave Neptune]

Joe, try a vinegar soak. Might even do twice if it is really bad. Each soaking should be for at least 24 hours when using vinegar~it needs time to work.

The shop can easily do it for a price.

Dave Neptune

[hanleyclifford]

Your local gun shop can sell you the neatest little brushes that are ideal for the purpose.

[Al Schober]

Joe,
I had a heat exchanger for an Onan genset that I had to drill out. Guess it depends on what you find when you open it up.

[Wrsteinesq]

Heat exchanger clogged

I had purchased a used heat exchanger. In my area, I cannot find any sort of "radiator shop" to boil it out, so I put it in a large stainless pot, filled it full of water and CLR (calcium/lime/rust) and actually boiled it over a crab cooker. I let it go for maybe 30 minutes, and it seems to have done a fine job. I'm not sure, but I'm betting that that process was similar to what a radiator shop would've done.

Does your particular heat exchanger allow you to unbolt and remove the end caps? Mine did, and that allowed pretty good access to the internal piping so it could be "rodded" out.

[jstaff]

Thanks for the replies.

My HX looks exactly like the one MM sells, with the caps on the tank ends. I'm not going to do any "cooking" of the heat exchanger but I believe that I'll run some muriatic acid or "CLR" through the cooler. I did a little homework and a product called Rydlyme was recommended but not available locally. It's a product containing hydrochloric acid (muriatic acid).

The CLR contains lactic acid.

Perhaps I pop the end caps off before using any acid, it might be photo-worthy.

[edwardc]

I have the Moyer HX, and had to clean out mine this spring. Its a simple job once the HX is out of the boat.

I found that the lower end was filled with a gray, granular "paste" that appeared to be the oxidized remains if several season's worth of zinc anodes. It cleaned out quite easily, with no need of acids. A straightened coathanger cleaned out the tubes nicely. With two new rubber end seals everything went back together and worked good as new.

[jstaff]

I removed the heat exchanger yesterday and this is what I found.


There was a major buildup of minerals in the raw water inlet.






And there was the debris from zincs in the bottom end.


I'm guessing that a 22 caliber bore brush would enter the tubes but maybe a larger one will fit. Does anyone know for sure?

A little manual and acid cleaning will be required.

[Administrator]

Would teflon tape on the threads of the sacrificial anode compromise its performance?

Bill

[jstaff]

Would teflon tape on the threads of the sacrificial anode compromise its performance?

Bill

Yes

The anode should have good contact with the HX.

[joe_db]

Possibly. It depends on if the threads cut through the tape and make electrical contact.

Would teflon tape on the threads of the sacrificial anode compromise its performance?

Bill

[hanleyclifford]

From the picture it does not look like the zinc actually sacrificed itself in a galvanic cell, but rather broke up and clogged the works. BTW, who knows what metal in the exchanger is the one being protected, and which metal is the aggressor?

[joe_db]

Oddly enough on plumbing forums telfon tape is talked about as NOT a good insulator because it rarely provides electrical isolation. Apparently it is very much YMMV on what happens. I have seen zincs with wire terminals to enable a ground connection other than the screw threads.

[hanleyclifford]

Oddly enough on plumbing forums telfon tape is talked about as NOT a good insulator because it rarely provides electrical isolation. Apparently it is very much YMMV on what happens. I have seen zincs with wire terminals to enable a ground connection other than the screw threads.

Thanks for putting that bubbe meise to bed.

[edwardc]

No, Teflon tape does not act as an insulator. The way it works is that the threads cut through it where there is thread to thread contact, and the resulting thin strips of teflon are compressed into the valleys of the threads, functioning as a packing paterial to prevent water migrating along the threads.

You can see this when you undo a fitting that has been sealed with teflon tape. The tape in the mating area has been reduced to thread-wide strands.