The heater core is clogged on my 2000 Blazer. Can I use CLR to clean it out?

Question

What is the best way to flush the heater core?

Answer 1

The best way to flush the heater core is to remove both hoses and flushed it with a garden hose. Make sure you flush it both ways.

Answer 2

NO!!! It will attack the aluminum in the engine. Go ahead and flush your cooling system with a chemical you can buy at your local auto parts store. Then remove the heater hoses and flush water through your core. It probably won't completely clear the blockage, but can help until you can get the job done properly.

The only way to do what you want to do with CLR safely is to remove the heater core and try to open it up using the CLR. And if you're going to take the time to remove the core, you might as well replace it with a new one.

The procedure to change the heater core is involved, but nothing a novice couldn't do in a weekend. Buy the repair manual for your car and the part you need and get going.

good luck.

Answer 3

GM has a TSB out on this problem. Your local dealer will know all about it :)

In the industry we call it the"GM Superflush".

The Prestone cleaner listed above is used as part of this service. It is most effectively done by someone with the proper equipment and takes about 3-4 hours IIRC.

Answer 4

Take the bottom radiator hose off & run water through the radiator.Use a radiator chemical to clean it out.If this doesnt do the job take it to a radiator shop.

Answer 5

the best thing to use is is prestone cooing system cleaner gm part number 12346500 , available at most gm dealers, because you probably also need to flush your radiator also

Answer 6

Give it a shot... I think the whole dash has to come off to replace it (not positive about that) and anything is better than going through that! I dunno if it would cause damage- but maybe use a plastic pipe mild form of drain-o?