Well, removed the t-stat and car is still running hot...

[RUNINAGT]

You said that when it runs hot the heat dont work correct? Then when the temp comes down the heat starts working? That sounds like the heater core may have a blockage in it, that keeps freeing up then blocking again. You figure if the core blocks up then the coolant stops flow and the engine will overheat. You also loose heat. Helping you reach in the dark. Good luck. If these are the symptoms then I think that would rule out your guage, guage should have nothing to do with your interior heat.

 

[5spd GT]

Thanks James

RunningGT - That makes a lot of sense because I started using my heater about the time all this started to occur. I want my heater...I was talking about replacing my heater anyways because it wouldn't "burn" me out of the car like I would like...so I'm going to have to do a different teardown to fix this possibly (interior)...great

 

[MrKwik]

If your lower hose doesn't have the spring in it, could be that is's sucking shut. I could definately see that causing cavitation in the cooling system which would make the heater not work when the air pockets form in the heater core. Oddly enough, those same steam pockets will make the temp guage read hotter than when there is hot water flowing over the sensor. And in my experience, pulling the Tstat out of the system usually makes it run hotter since the coolant doesnt stay in the radiator long enough to pull enough heat out. It also makes it take alot longer to heat up. I would get a new 180 stat and replace that lower hose and go from there.

 

[5spd GT]

Is their a way to check that lower hose? Thanks for the suggestion...

edit: I have squeezed the hose when the engine is warm/hot and it doesn't budge much at all.

 

[mackey]

The whole thing with coolant flowing too quickly might have been true back in the day (low pressure systems) but it is not so true now. The longer coolant is in the motor, the more opportunity it has to boil off (hot spotting). One wants to force it through the system at decent velocity.

Yes, but the thermostat acts like a one way valve letting the coolant sit in the radiator and have time to cool off before it opens back up again. So it will make the heat problem worse because it doesn't allow any of the coolant to cool down before it goes into the engine.

 

[5spd GT]

mackey - It passes thru the radiator at about the same speed as it passes thru the engine. About the same time to heat up and cool down. Almost seems to cancel it out on both ends. Thanks for all the responses.

 

[TheUser]

well...if you're leaning towards heater blockage or any problem involving the heater, you could just get an infamous "loop" hose to temporarily loop the coolant and bypass the heater alltogether. I know you want your heater, so you may not even consider this, but it may be a way to test and see if the heater is your problem.

If you do that, be sure to burp the system again

I know it would suck w/o heat, but I'm north of you and I drive w/o the heat on half of the time anyway (vehicle not warmed up/forget to turn the heat on); it sucks, but I live.

Good Luck.

 

[5spd GT]

Right, I have been driving without any "real" heat for about a month now so I can live for a few weeks even though it is starting to get in the 20's

So what about that loop? What do I need exactly and how do I go about doing it?

 

[TheUser]

well, you just get a hose shaped in a half circle; go to the auto parts store - you could take your old hoses w/ you for sizing if you wanted and get one that's a half circle to loop back around. When you look at it, you'll see what I mean. You could ask them if you can go look at the hoses yourself to decide which one you want.

You're basically taking the coolant that would be flowing to your heater and looping it back around where it would be flowing back to the motor - effectively avoiding the heater alltogether.

If you have questions, let me know, although I can't remember if I've done this before or not, it seems pretty straight forward.

 

[RUNINAGT]

Give it a try. Hope it works for ya. I know it's an expensive job to replace the heater core. Unless you can do it yourself. I work @ a repair facility and paid my employee rate for one of our tech's to do it. I dont have the patience to attempt that. Try it for a few days or a week. If it dont overheat anymore then whalaa.

 

[5spd GT]

I can do a heatercore replacement. $70 bucks for a OEM one and labor is free (but impatient)...will see how it goes...it will be a bit before I attempt it. I will wait till I tear it down first and go from there and see if that is the reason...

Thanks again running and James

 

[HISSIN50]

Mackey, I dont come up with this stuff out of my arsh. It comes from having done a good bit of research on cooling systems. Stewart's site has a good tech section - I know they echo the same sentiments I did. There are other sites, but I liked that one and remember it.

David, good luck with the heater core loop.

 

[BlackGT89]

5spd, someone asked earlier about looking into the radiator for circulation and I'm not sure I saw a reply to that. I would check that (carefully of course). You might even want to let the car warm up from dead cold with the cap off and be careful when the thermostat opens. I've seen a guy that was scalded by antifreeze and it's not a pretty sight (it takes antifreeze much longer than water to cool off even after it hits the air). It's possible some of the vanes on the water pump impeller have broken off or the impeller itself might have sheered off. I've never seen that on our cars, but I have on some older ones.

 

[5spd GT]

By circulating you just mean seeing the fluid move around. I can watch it I guess, but it is a different design than a stock radiator but should work the same. I'll try to take a look...I'm not afraid of coolant

 

[RUNINAGT]

I've heard of the impellar's rusting. I've seen that aon some cars coming thru our shop. We have an 18 bay shop that takes on the average of about60-75 cars daily. Doing everything from tire repairs to drivability issues. Just dont go internal of engines, (like doing crank and camshafts, but do timing belts) dont rebuild trannies or rear ends. But pretty much everything else. Once agin good luck.