Co-Worker needs some info... '99 Blazer

Caver Dave

Caver Dave

Just holdin' it down here in BFV
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One of my IT brothers is in a Jam!

His wife's '99 Blazer 4x4 4.3L auto is slowly crapping the bed. About a year ago, they were having "no heat" issues... I found the radiator and overflow full of gunk & deposits. We pulled the thermostat, dumped in a bottle of flush, ran it for 20-30 minutes, and flushed. After reinstalling the t-stat & filling with orange Dexcool, everything was good, but the rad still looked pretty bad.

Now, it's the same symptoms, but he says there is gunk in the overflow again and the water pump is leaking. He was gonna just replace the pump, but I think maybe one of the wienies at Sears (has been serviced there) added some non-Dex and that has caused everything to jelly up. There is NO heat from the core when warm and blower running...

Questions for those in the know:

#1 - Will mixing DEX & green AF (not the "works with any color" stuff) gunk up the cooling system?
#2 - If so, what the best way to flush it out?
#3 - Will the heater core require additional purging (compressed air, etc.) to unclog it?
#4 - Assuming the core has to be swapped, on a 1-10 scale, what's the PITA factor?
 
About the only way to get that gunk somewhat out of there is to replace the radiator and the heater core. We flush them with a water hose going both ways. But they usually just keep stopping up. They say mixing doesnt hurt anything i i think different. Just flush him out as best you can and put in green coolant. Heater core is not too bad as long as you have some idea of what your doing.
 
DEX cool is known to crystalize with excessive heat, which a 4.3 is good for emitting, given the tight confines in the engine bay. there are a few places in the cooling system that the coolant is stagnant ( not moving well, if at all ) that this crystallization takes place ( rear of head at intake where coolant does not flow is one place)

Dex will also sludge up if mixed with green AF, takes time but it does happen. and DEX is NASTY smelling when it is not changed or serviced with regularity.

Heater core in a S-body ANYTHING is a PITA, dash removal is required (there are bolts you cannot see that need to be removed), if it ain't leaking, try to flush it out best you can.

If you are going to replace the water pump, buy intake gaskets as well, reseal it at the same time, as they will blow shortly after. leaking either externally ( may already be seepig now ) at the head behind the AC mount or the ALT mount. Some times they will blow internal mixing oil and coolant ( Strawberry Mocha anyone ? )

flush the hell outta the system, use good green antifreeze as replacment after all the other work is done.

Replace the T-stat while yer at it.

Kevin
former Mr. Goodwrench
 
Voodoo speaks the truth. For extended life coolant that actually works well and is reasonable, try the Benz coolant. Its about 14 buck a gallon and works. It has no dye in it tho' so you'll get people telling you you need antifeeze. It will mix fine with green long and short term and I've never seen it become eletrostatic like green will.

Gunk makes a flush that I used on the runners core that worked wonders. I poured it in straight, let it sit for 30 min. and flushed it with straight water. Went from 60 degree heat to 140. Screw DEXCool, Id rather run washer fluid.
 
Ratman said:
Screw DEXCool, Id rather run washer fluid.
Click to expand...

Amen to that. Dexcool sux. Get rid of it ASAP, in everything that has it. It also make everything hard to get apart and deteriorates some of the components in the system. We had the Lee Co emergency management burb in the shop a while back and the hose on the back of the intake was leaking. Heater hose I think. It actually ate the fitting apart at the intake and it was a real PITA to get out. We recommend everyone get rid of dexcool in everything. Even brand new stuff. Saves a lot of problems down the road.
 
My pontiac transport van (when my dad had it) had the same problem. the head gaskets blew as well so you might start expecting that. The headgaskets don't like the jelly, or should I say the change from orange to green.

It's like its corrosive or its a combinations problem or something.

When they took the engine apart to do the head gaskets, they were like dissolved or something. they had to vat the radiator, and as far as the heater core was concerned, they just flushed it several times.

that stuff is nasty
 
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