So the folks on LS1Tech.com dont wanna respond. Lookin for opinions.

While on the move and in gear, my car has no problem getting and maintaining heating for the cabin. Once I get the car out of gear, as in idling to a light or idling at a light, the car will no longer warm the interior of the car and the engine will start overheating. Is this indicative of a heater core, bad t-stat, or something I've yet to think about? thanks yall!

sounds like fans might not be coming on, have you checked that?

oh, there's plenty of air movement inside the cabin, so the blower is working. It's also not the blower resistor. Also the radiator fans do work. Thats why this puzzles me so. Thanks for the response.

sounds like a stuck thermostat

Either a stuck Tstat or a clogged heat exchanger.

is the heat exchanger the same thing as the heater core?

Will a system pressure flush restore the heat exchanger/heater core, or is a replacement required? Also, be aware that my interior is dry.

The tstat SHOULD be brand new. I had them install this thing when they replaced the engine. Guess I have a replacement to do, huh? The interesting thing is that the car warms up normally, and stays warm while on the move. Whatever. Tstat will be replaced this paycheck.

Thanks for the replies!

Stuck T-stat could be it. I've seen brand new ones stick...

Clogged coolent line somewhere? bad radiator? All Fluids up and full? Low fluids will give this same senerio.

Heat exchanger/core same thing

Just thought of something. Not enough cooling while at idle with fans on and no cabin heat?

Next time rev the motor and see if things improve. I wonder if you might have a water pump issue. Either a loose belt or pump starting to freeze up.

Check coolant level

Could be start of bad water pump.

w/p, got the check. Thanks. There has been a squeal in the bay. I thought it was the clutch fluid being BLACK black. But it did resurface today.

Tstat will be replaced soon.

Very certain fluids are up.

I have a year-old GatorBak on the car, so I am MORE than certain it aint my belt. I'm still running my NM GatorBak on the GP with NO signs of even a little wear.

I think I'm hearing to flush the system and see if that jars something loose. If not, I'm looking at heater core (thanks for that definition, Herc ).

Hey, all, for your replies and help:

It sounds like a partiall- plugged heater core for sure ,a good flush ma- do the trick other wise U will have to change ,did U ever use an- coolent stop leak? these products will plug up a cooling s-stem.Chico(pops)

Keep in mind if the flush doesn't work you may have to replace the heater core. If the tubing is lined with crud (think about a fish tank with algea all over everything) It may not come off with a flush. If that's the case the crud could insulate the tubing and not allow a proper heat exchange.

Chico: nope, never used any of that crap. After seeing what water does in a tire, and being told that No-Mor-Flat does the same thing, I vowed off of using clotting agents. What I will not say is that the previous owner did not use that garbage in the previous engine.

Herc: After the tstat (tomorrow), and the the flush (in about 2 weeks), would you recommend heater core first or the w/p?

Thanks gents.

Sometimes you can relieve system pressure and disconnect the heater core lines and just flush them with water from a hose. You need to flush in both directions a few times. My co-worker needs to do this every fall on his 2000 Chevy truck to get heat. He said he never sees anything come out, but he gets heat after each time he does it.

You might find after doing the flush that the water pump might get a leak. It happened to my '98 after a complete flush of the system. After driving 30 miles, sure enough, my water pump started leaking after the flush.

There's been talk (not here, but on the Cadillac forums) that you can use CLR in the heater core to remove anything that might be clogging it up. You have to take the hoses off the core and pour the CLR in the core and let it sit for ~30 minutes, then do a reverse flush with a garden hose to get all the 'gunk' out of it. I haven't tried it myself, but it might be worth a try and a lot cheaper than replacing the core.