The heater core on my daughters GMC Jimmy seems to be plugged. Its not a
full plug as some water comes out but the hose is cool. I have called around
and its over $700 to replace it and its not a job I can do with my
shoulders. I was told by a shop they could flush it for $70. I went to auto
zone and found Prestone Super Cleaner.
What are your thoughts of investing the money for a flush or should I try
the cleaner and flush it myself. I was told by one garage they flush with a
garden hose and I am thinking hell I can do that.
It would be unusual for just the heater core to clog without some issues in
the rest of the cooling system, before you spend any money here, I would
take the rad cap off and drain enough coolant to see down in the radiator
and look at the cores and general condition of the coolant, see if it looks
I did flush it the best I could with a garden hose. I replaced the cap it
was filled with a rusty gum. The reservoir is a reddish rust color. Inside
the radiator the spring looking thing that I think is part of the
transmission cooler was covered with this same rusty looking crap. My
question is will the cleaner do as good a job as the $70 flush from a shop?
The flush is worth a try in this case. Although it sounds like you have a
coolant leak somewhere. Maybe the intake? The coolant gets rusty, slimmy,
like your saying when there is a air leak. So the flush might help for a
while but intil the leak is found and fixed you might run into this again
in 6 months.
The rusty looking crap might very well be stop leak.
Better parts stores will have Permatex radiator flush available,
comes in a quart bottle. It's acid so use appropriate caution.
1/3 to 1/2 bottle depending on how dirty the system is. Follow
the directions on the bottle.
You need to reverse the flow thru the heater core to loosen the
muck. Your FLAPS should be able to sell you 5/8" to 3/4" hose
adaptors, you need two and one piece of 5/8" heater hose and one
piece 3/4" heater hose, 4"-6" long. Install the short pieces of
hose with the size adaptors so that the inlet and outlet heater
hoses can be reversed, flush the cooling system until clear water
runs, add the Permatex radiator flush and drive the truck for
15-20 minutes fully warmed up.
Flush the system again, let the water run for 20-40 minutes, best
is if you open the block drains so everything that might be
trapped in the block has a way to escape. Change the heater
hoses back to where they belong. Refill with fresh Dexcool in the
proper mix. Replace the radiator cap, fill the overflow to the
I've had 100% success doing this on S and T trucks with blocked
heater cores, and it beats the hell out of pulling the dash and
changing the heater core.
Naturally, if you're going to do this, you'll want to make
absolutely certain that the intake manifold gaskets haven't failed
(i.e., has it had a history of coolant loss?)
I have had to add a small amount of coolant now and then but really don't
know how much. If it needs a new heater core, and A/C is also not working.
My thinking is try the flush if still no heat its time to replace the car.
Reading paraphenalia with my new heater core replacement mentions voltage in
the coolant itself causing electrolysis. Little as .1+ volts is all that
needed. The worst of it will be where the ground is located in the cooling
system. IE radiator or heater core.
Where the heater core integrated pipes enter the firewall from underhood,
there's a bracket (metal) that separates and contacts the two pipes and is
bolted to the firewall. And the two bands that hold the heater core proper
are metal, use two metal screws each and are bolted to the firewall inside
the passenger compartment. 94 Chevy Blazer S-10, V-6 4.3L Vortec engine,
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