Clogged heater core fix-it tips needed

[TR Custom Parts]

OK, so it's not my GN's heater, it's on my wife's 98 JIMMY. Buick content = It's parked in the heated garage next to my GN. She complained of no heat this week and checked it out this afternoon after driving it around to get it up to operating temp. Felt the heater hoses and it was warm going to the core and cold coming out so obviously it is clogged. Anyone have tips for trying to get it unclogged? Don't really want to try and replace it right now as it is a major paint in the butt. (did a heater core on my 96 Blazer and my son learned some new words )

It has the damn Dexcool coolant so maybe that has something to do with it. Can I just disconnect the lines to the core and try to blow it out with compressed air or will a coolant flush do it?

Have also been told that once you use Dexcool you can't convert to regular "green" antifreeze, any truth to that?

 

[Topjimmy]

I've been able to flush out cores by disconnecting both hoses and putting the garden hose to them. I've also heard that once you go pink you can't come back.

HTH - Jimmy

 

[trbo668bird]

Sounds like you have a classic case of Dex-cool. I've had pretty good luck with back flushing the heater core with a garden hose, just unhook the lines and stick the hose in the outlet nipple (the one that doesn't get hot) with the hose on fairly low, don't use too much pressure because it may pack the goo in really tight then you'll have no choice but to replace the core.
Yes you can and should put green back in, the catch is you MUST get every last trace of pink(or orange or brown) out of the system. If you don't you'll end up with a cooling system full of jello, just like what you have now, only worse. Best way is to stick the garden hose in the radiator and leave the heater hose disconnected from the front of the intake manifold let the engine run until the water comes out clean, reconnect heater hose let the engine warm up completely (t-stat open) then remove the heater hose and flush it some more. Repeat until clean.
Don't be surprised if your intake manifold gasket and water pump start leaking within a few months since you have now flushed out all of the goo that kept them sealed.
Sorry for the bad news, but better to be able to plan for it.

 

[TR Custom Parts]

Got it! Flushed it thru the heater hoses both ways. Water flowed both ways and then there was a surge of water so I guess I pushed out whatever was in there. Had heat by the time I reached the end of my street. Thanks guys, hope this fixes it for good.