OK to flush heater core with Drano, Limeaway, or CLR?

[j]

My 1994 Chevrolet Corsica is putting out lukewarm air from the heater. I
installed a new 190 degree thermostat with no improvement. I have verified
that very hot water is being sent to the heater core from the water pump. I
know that the vacuum-controlled "flaps" in the air duct are working because
I can hear them when I adjust the selector knob, so it must be the heater
core.

I bought a heater core, then found out that the car must be lifted and
placed on jackstands, the dash removed, and a lot of other awful things just
to change the heater core.

Rather than go through all this, will it work to disconnect the two water
hoses from the heater core, blow the coolant out of the heater core, then
pour in either some Drano, Limeaway, or CLR, let it sit awhile, then flush
it out with a garden hose?

[Scott Dorsey]

j <durhamb...@sbcglobal.net> wrote:
>
>Rather than go through all this, will it work to disconnect the two water
>hoses from the heater core, blow the coolant out of the heater core, then
>pour in either some Drano, Limeaway, or CLR, let it sit awhile, then flush
>it out with a garden hose?

Drano is the opposite of the other two. It's an alkali intended to
break down grease. You don't have grease in your lines. Limeaway and CLR
both are acids that are intended to attack corrosion.

I suggest that if you want to try something like this, you use Prestone
radiator flush, which is an acid much like CLR but which has been tested
fairly well in cooling systems.

You should know, however, that if you have a heater core that is plugged,
it may also be well on its way toward leaking, and cleaning it out with
the radiator flush may take it all the way over the edge. But it cannot
hurt to try; the worst case is you'll have to replace the core anyway.
--scott

--
"C'est un Nagra. C'est suisse, et tres, tres precis."

[j]

Thanks Scott, I'll give the Prestone a try. I appreciate your help.

"Scott Dorsey" <klu...@panix.com> wrote in message
news:geiik7$fj6$1...@panix2.panix.com...

[Kruse]

On Nov 1, 11:17 am, "j" <durhambusdri...@sbcglobal.net> wrote:
> My 1994 Chevrolet Corsica is putting out lukewarm air from the heater. I
> installed a new 190 degree thermostat with no improvement. I have verified
> that very hot water is being sent to the heater core from the water pump.

If nothing else works, try taking the two heater core hoses off and
GENTLY reverse flush
your heater core with a garden hose. This may be a last resort and it
could make your
heater core leak, just like all the other methods you mentioned.