I am new poster, but have been reading these forums for a while now. First off, thank you for all the help thus far. I have a 98 gmc jimmy slt and have done pretty much everything to it myself. I have gone through the search engine and found some great info, just not exactly what I need.

I put a heater core in a year or so back, and no problems after, everything worked fine. I put a thermostat and hoses in just this past year, do to some overheating, again everything back to normal and worked fine. About a month ago I put in a new water pump, due to leakage, cooling returned to normal and temp sits at maybe 200 consistantly. Now I have no heat at all. I can hear all the vents moving when I swith between settings, and blower works fine. Fluid is full, pulled the hoses for heater core and flushed it, flows freely. When the engine is warm, I can grab the heater core hoses and one is barely warm, the other is not at all. Any suggestions would be greatly appreciated. Is there a heater control valve on this?

 

if one is cooler then the other by that much then you still have a flow issue.
when you flushed did you flush the core or the core and the lines going to it?
is the cooler of the two the one going to the waterpump?
it might be plugged there.

 

The cooler is the one going to the water pump, I flushed the hoses and the core, I also hooked the one to the manifold and flushed through the hose goint into the water pump, and it pushed out the heater core. Even the first flush forward and backward was easy, a little of the typical crud, but it flowed without resistance.

And the one hose may be warmer than the other, but even it is barely luke warm, not at all what I would expect it to be.

 

Your baby could just need a little burping. Elevate the front of the vehicle and run it with the radiator cap off for half an hour. Add coolant as needed if it burps.

 

Thanks guys, I'll try burping it and hopefully thats all it takes.

 

Just an fyi update. Figured out the problem and the heater core is indeed clogged. I am able to flush and backflush the heater core and get clean water running through it, but the line running to it will heat and the one from it will not. I had an old mechanic tell me that it doesn't always matter, because water will run into the heater core and it is just forced through the end and doesn't pull through the veins. The solution is to put a heater core in it, which I'll be doing this weekend. This is all thanks to the muddy dexcool crap that I'm still trying to clean out of the system. Pure garbage imo.