NOT AGAIN! - Heater Problem

[ammcf1]

1994 Automatic Geo - 3-cyl, 1.0 liter - 94,000 miles.

Just this last Oct. or Nov. I replaced the thermostat, flushed the radiator and heater core (no debris there at all) and reattached everything. After doing so, everything was great - REALLY HOT heater, no problem.

NOW, things have changed a bit - the heater puts out warm air and is adequate at defrosting, etc. but it doesn't get HOT like it used to. What could be causing this?

Thanks

[$400chevymetro]

Not that unusual to have a thermostat go bad or get a bad one so don't rule that out. What does your temp. gauge read? First you might check radiator fluid level if you haven't. Start car and bring to normal running temp and feel your inlet and outlet heater hoses the one going in should be hot and the one coming out should be warm, if they aren't check thermostat. Next you might try checking your temperature door by switching from cold to hot quickly and listening to see if the temp. door slams shut. Just a couple of easy to check suggestions if it's none of these post back.

[ammcf1]

OK, here' the update...

Just after you posted, the temp. guage began going wacko. Even after 2 hours of driving it is pegged out at the bottom. That even AFTER replacing the thermostat yesterday. Here's what I've done...

* Fluid levels in the coolant system are topped off.
* NEW thermostat has been installed.
* Neither the inlet or the outlet hose to the heater is HOT after the engine has been running. Both are merely warm.
* Any time I come to a stop and remain there for at least a minute, the temp. guage begins to climb slowly. But even then it never gets to it's "normal" spot. The most I've seen it get is only 1/4 of the way up the guage.
* The temperture door sounds to be fine. A definite "flap" when it is moved side to side.
* The heater STILL provides only moderately warm air. Enough to defrost but not enough to take the chill out of your bones! It's been very cold here lately (-10 at night).

My thoughts...

Could this be related to a sensor of some sort? Given that the heater still warms some, and that the temp. guage is wacko, I don't think it's the actual heater itself, do you?

Will driving it in this condition harm the engine, just until I can get this figured out? I use it for early morning paper delivery, 2 1/2 to 3 hours each morning.

Thanks

[leonbentz]

Yea, it sounds like a faulty thermostat to me.

[Crvett69]

when you flushed the heater core did you have a good flow coming out of it?

[ammcf1]

Yep - it had great flow coming out...

With the temp. guage not working well, I tend to think it's not the heater itself. A friend just told me the old cardboard in front of the radiator trick, just to see if it's the cold temps. we've been having. When I stop for 5 minutes or so, the temp. guage and heater start to work properly

[Mikey_K]

Have you check out the radiator cap? If the system isn't pressurized (the cap's rated for 13 psi), it doesn't work right.

[ammcf1]

Radiator cap is fine...

I tried the cardboard in front of the radiator trick and it seems to be working. I realize that I'll have to keep a close eye on it to make sure that it doesn't overheat as the outside temps. rise.

A question though... What does this kind of temporary remedy indicate is the real problem?

[Crvett69]

what temp thermostat did you put in it. aluminum sheds heat so fast you might just have to run the cardboard in it till it warms up, when it gets that cold even the big diesel trucks have to block off sections of the radiator to get engine to run warm enough, often you will see them with a pice of material over the outside of the radiator zipped most of the way up blocking air flow to it off

[ammcf1]

I believe the thermostat was a 155 degree. The cardboard over the entire radiator is keeping it right at 3/4 on the temp. guage (normal) and the heater is blowing hot. Thanks so much for your help Crette69!

[DOCTORBILL]

When I replaced my thermostat in my '93 3 cyl (The Phoenix), there were
only two temps available -> 185 °F and 195 °F.
Does anyone even make a 155 °F thermostat !?

I put in the 185 °F to keep mine cooler in hot summer weather.

Is your water pump working well?

What is the outside ambient temp?

If it is around 0 to 10 degrees Fahrenheit, then, indeed, you should put some
cardboard in front of your radiator - the radiator for the engine on the right side
where the electric fan is located.

I have needed to do that on several cars!

That little motorcycle engine, all exposed, in a Metro loses heat quicker'n a
gambler loses his paycheck in Vegas!

The whole damned engine setup weighs only 17 lbs...! Rubber Band and all.
And my Guinea Pig that runs on that wheel pees all over the transmission!

Mine takes forever to heat up and cools off within minutes after parking it.

DoctorBill

[Crvett69]

run a 195 degree thermostat in the winter. might check it or replace it if its a lower temp, can switch back to a cooler one in the summer if you need to

[RossT]

It almost sounds like you have air in the system (wacky temp gauge/luke warm heater hoses) or maybee a bad headgasket allowing air to get into the system. Are you loosing coolant and can't find a leak? Also, some aftermarket stats don't have a drain hole in them, making bleeding the air out a little harder to do.

[way]

Another thing you can do to increase heat inside the car is to experiment a bit with your fresh air / recirculation setting. I've got mine about 2/3 towards the recirculate position. It seems to heat better and the windows are staying clear.

[emack]

Another thing to check, is the seal around the thermostat. If I remember right I had a thermostat that had a channel shaped gasket that snaps over the edge of the thermostat. If that gasket is missing then there is room for your thermostat to move up and down a small about. that might explain why it take a while to warm up. If I remember right the gasket is somthig like 3/16 to a 1/4 thick. I threw away my original thermostat with the old gasket and when I bought a new one I had to use sealer. the sealer didnt hold the thermostat in place. I didnt realize this until I checked it several times.