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flushing heater core

Old 04-23-2009, 11:08 AM
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Default flushing heater core

whats the best way to do it?
Old 06-13-2009, 07:25 PM
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Thats what i would like to know.....Maybe you have the same problem as me , the heater is not geting hot due , presumably to the heater core being full of rust and gunge.... I have pulled of the metal inlet and outlet tubes and stuck a hose on the heater inlet , but water is not flowing very well through the heater... When the Jeep is running the inlet pipe gets pretty hot , but the outlet pipe is pretty cool , suggesting that the problem is a blockage in the heater core... I would love to solve the problem without taking the whole dash out if possible....any suggestions guys....?
Old 06-13-2009, 07:56 PM
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The two hoses that run down the side of the valve cover supply the heater core. Remove them both, get a radiator flush additive and pour it in the top hose untill it comes out the bottom hose. Let the additive sit in there for about an hour, then flush it with water. It works best if you couple it directly to a garden hose, flush it till it runs clear and then switch hoses.
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Old 06-13-2009, 10:03 PM
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the engine heat and pressure along with some prestone flush will work best....
Old 06-20-2009, 06:33 PM
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I shall try both methods...thanks guys....I don,t want to be driving around through a Polish winter without a heater....it can get down to minus 30 round these parts , when the weather is blowing from Siberia...
Old 06-20-2009, 07:58 PM
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Connecting a garden hose is a good way to go, but bear in mind a couple of things:

1) Run the water through in a reverse direction. Deposits look like fish scales - running water through "backwards" tends to lift those scales and break more crud free. Running water through the right way will only remove stuff that's already loose.

2) Make sure you get all of the tap water out before you refill, or you'll be having this trouble again.

If you suspect a great deal of built-up scale and sediment, you're going to want to use a fairly strong chemical flush (usually acidic) to break it loose. The good flushes will come in two parts, with an acid flush and a neutraliser. Follow the instructions exactly - the only variation I'd consider would be letting the neutraliser run a bit longer than called for (the acid is caustic, but the neutraliser typically is not.) Don't use tap water when you refill - drain out as much as you can and then refill with coolant cut with distilled or reverse-osmosis filtered water (this removes most of the dissolved solids and metals that form deposits when left unchecked.)

Once you've got it all nice and clean, a mild flush and change the coolant is usually all that is required every alternate year after that. Old coolant may usually be taken to an automotive radiator repair shop for recycling, or find a local school that offers a "hands-on" automotive programme.

Failing that, you can check with your local water company, they may accept coolant poured down the drain (but it depends heavily on the process they use for water purification.) This is a last resort - you can usually find a shop or a school that will take it off your hands, and usually for free.
Old 10-12-2009, 11:03 AM
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hello, I was just wondering where I could get some of that two-part (acid/neutralizer) coolant flush. I stopped by a couple of local auto parts stores and they were unfamiliar with such a product. Is there a brand name I could search for, or an online resource?

Any information would be greatly appreciated. Thanks in advance.
Old 10-12-2009, 05:24 PM
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Originally Posted by tom frost
hello, I was just wondering where I could get some of that two-part (acid/neutralizer) coolant flush. I stopped by a couple of local auto parts stores and they were unfamiliar with such a product. Is there a brand name I could search for, or an online resource?

Any information would be greatly appreciated. Thanks in advance.
I typically get it as a Prestone product, it's in a yellow paper cannister about 6-8" high and 2" in diameter.

Both components are powdered, and don't activate until you mix them with water. Do not mix them with each other, beyond as stated in the directions!

Follow the directions EXACTLY, save I usually do an additional plain water flush after the neutraliser is run.
Old 10-16-2009, 06:42 PM
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Thanks for the reply and info, it's greatly appreciated. I'm going to try to track down some of that product in my area. In the meantime, I did purchase some Peak brand coolant flush (not two part, but acid based). I disconnected the supply and return lines (leading to and from the heater core), flushed it with water, blew all the remaining water out, filled it with the Peak coolant flush I bought, let sit for approx. an hour and a half, flushed with water again, blew remaing water out one last time, and reconnected the hoses. I started the Jeep and let it run, after a few minutes the heat was back. It was not quite as hot as before, but about 80-90% as hot as before. It has been a week now, and things are still fine.

I intend to flush it again as soon as I get the chance (and hopefully with the two-part product you mentioned above), but overall I think it has worked out fine. I'm pretty pleased to have avoided paying a shop to replace it. A local mechanic I called gave me a $500-$600 ballpark estimate.

Anyhow... thanks again, this is a great forum. Very helpful, with good info.
Old 10-16-2009, 06:51 PM
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Originally Posted by tom frost
Thanks for the reply and info, it's greatly appreciated. I'm going to try to track down some of that product in my area. In the meantime, I did purchase some Peak brand coolant flush (not two part, but acid based). I disconnected the supply and return lines (leading to and from the heater core), flushed it with water, blew all the remaining water out, filled it with the Peak coolant flush I bought, let sit for approx. an hour and a half, flushed with water again, blew remaing water out one last time, and reconnected the hoses. I started the Jeep and let it run, after a few minutes the heat was back. It was not quite as hot as before, but about 80-90% as hot as before. It has been a week now, and things are still fine.

I intend to flush it again as soon as I get the chance (and hopefully with the two-part product you mentioned above), but overall I think it has worked out fine. I'm pretty pleased to have avoided paying a shop to replace it. A local mechanic I called gave me a $500-$600 ballpark estimate.

Anyhow... thanks again, this is a great forum. Very helpful, with good info.
when you do it again, dont forget to reverse flush it like the guys above said. i didnt even think about that myself,so im gonna do that when i flush mine out.
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