Gurgling sounds HVAC Dexcool?

adrenalnjunky · Post by **adrenalnjunky** » Thu Mar 10, 2005 12:12 pm

HJ--feel free to split this if you think it should be.

My gurgling has gotten worse over the last few weeks, but the HVAC controls are still functioning -- but now my heater is barely warming up.

I'm thinking I've got a heatercore gone on me, or at the least, a thermostat.

Anyone replaced the heater core on their truck yet? I'm just under 51K miles, and I seriously didn't expect a h-core to die on me yet.

Dextron-related maybe?

Post by **HenryJ** » Thu Mar 10, 2005 5:26 pm

adrenalnjunky wrote:My gurgling has gotten worse over the last few weeks, but the HVAC controls are still functioning -- but now my heater is barely warming up.

I'm thinking I've got a heatercore gone on me, or at the least, a thermostat....
Dextron-related maybe?

If you have air in the system, and are running Dex, those sounds are that death gasps of your heater core. If it is not yet leaking, pull both hoses and try to flush the core. Then remove the thermostat and flush out the rest of the system. You may be able to salvage the system.
Drain out as much as you can, fill with water run until warm, repeat. Do this as many times as it takes to come clean.
Remove the reservoir and clean it out. There is no other good way.

Pulling the heatercore will get VERY involved. Spending some time trying to salvage the system will be time well spent.

adrenalnjunky · Post by **adrenalnjunky** » Thu Mar 10, 2005 9:33 pm

Yeah I remeber me and my dad spending about 8 hours one night replacing the core in my 89 with the 4.3. Prob is the truck had 160K on it then -- wasn't quite so unexpected.

Figures the that one decided to die in the middle of January on the coldest weekend of the winter.

Oh well--I have a weekend project. HJ -- do you have a good - kinda step by step on how I should go about trying to flush the system?

Post by **HenryJ** » Fri Mar 11, 2005 8:59 pm

Well I just do about what I said in the last post.

Drain as much out via the radiator drain valve. Remove the thermostat flush what you can with a hose and reinstall cover without stat.
Take both heater hoses loose and flush water through the heater core. reattach the heater hoses. Remove coolant recovery tank.

Then fill it back up with water run it for a while and drain several times until it comes out looking clean.

I have also used the Prestone flush kit and system flush. The kit has a tee that you install in the heater hose and an attachment for a garden hose so that you can not over pressurize the system.

Run the system flush first after the drain and refill routine. Then cut the tee inline and run it for quite a while until things look clear.
You can just use the included tee cap, but I have had them leak after a couple years, so spend the $12 on a vacuum valve and do the heater control mod

Now drain the system down again, reinstall the thermostat , add two gallons of coolant (green would be my choice, but new Dexcool could be used) , reinstall the recovery tank and fill it with coolant. Make sure that you have a good cap. You did throw away that stock GM POS , right?

Squeeze the upper radiator hose several times to purge the air back to the recovery tank and you're done.