hot & cold running t-bird

[spidergirl]

i'm ready to drive this 'bird off a cliff to see if it can fly cuz it sure as hell can't drive...
in June, i spent over $1000 (canadian, which i believe is around $10,000 american...) getting the head gasket on my '90 thunderbird replaced, along with a few other minor repairs & repeated trips back to the shop.
now, the temp sits on cold for about 5 minutes of driving, then shoots up in the red for a few seconds, and after about 10-15 minutes, levels off, & i SOMEtimes get heat blowing. also, it runs extremely rough up til the point the temp levels off. a few people have told me it's the thermostat, which i know i could switch out myself. but, i've also been told to either get a new motor, or get a new car...which, thanks to the above mentioned repair bill, i cannot afford.
if anyone has a bit of advice, i'll love you forever!

[slickshift]

Well, you probably do need to change the thermostat
But if you don't mind I have a few questions

1) Which engine do you have?
2) The head gasket was replaced in June, when did you get the hot/cold weirdness? Before, after or right after?
3) What were the other minor repairs, and were they done before, after, or at the same time as the gasket fix?
4) Have you checked the coolant level recently?
5) Would you say the engine gets hotter/colder when you are sitting in traffic or cruising down the highway or doesn't matter?
6) When it levels off, where on the gauge does it level off?

OK that's technically more than a few, but the answers could be important in determining what is wrong with your 'bird

[spidergirl]

-It's a 3.8L V6.
-The temperature problems happened prior to the gasket being replaced. Then it happened only a few times a month at the most afterward...now, it's suddenly graduated to every time it runs.
-I had the rad flushed & tested, the heads tested, new head bolts, spark plugs & oil filter.
-The coolant is at the proper ratio & level.
-It appears to be more a matter of how long the motor has been running rather than how it's being driven.
-It levels at normal, and sometimes I get heat...sometimes not.

Oddly enough, the temperature here dropped from +12C to -25C over the weekend and the motor turns over easier and idles better. Possibly just evidence it was built in the Great White North!

[aaronr121]

Definately replace that thermostat. If that is bad and is sticking, if you over heat it, that will just kill another head gasket (probably why you lost one to begin with).
Also make sure the fan clutch or the electric fan is working properly. If you find it stays cool while you are driving at reasonable speeds and starts to over heat when you are stopped and idling, it's probably the fan. Either it will need a new clutch, or if it is electric, may just be a relay, or the electric motor is shot.
But with you having problems just keeping the car blowing heat, I'd say it is probably the thermostat.