hey everyone,

im a noob on this thread (and everything firebird). I recently got a 91 firebird 5.0 . the car runs amazingly, but it heats up slowly but surely. going from about 140 to 220 and over if i drive about 4 to 9 miles. I noticed the reservoir tank boiling over, so I burped the system and replaced the rad cap (it was in horrible shape). The temp still kept going up slowly but got to around 180 if im not mistaken. I just really want to know if the way it heats up is normal for our cars or if its just mine being stupid. thanks a million in advance.

 

Normal op temps for these cars is about 220. You can lower those temps by swapping in a 180 thermostat and by replacing the factory fan switch located inthe pass side head with a cooler switch. There should also be an air dam located under the car mounted right under the radiator - if it's overheating on the highway then make sure there is that air dam there. Is this a TPI (tuned port injection) or a TBI (throttle body injection) car? TPI has an injector for each cylinder, TBI has what looks like a carb on top but it has 2 injectors inside.

 

I want to say its TBI. The airfilters are different no?

 

TBI has what looks like a normal old school air filter - round.

 

yea thats it.

 

OK. Make sure it has the air dam underneath the rad. These cars run hot - GM's brilliant method of reducing emissions. Most of us like them to run cooler. I never had any luck with the factory style fan swithces - even expensive aftermarket ones crapped out on me all the time. I went with a seperate fan controller - it's fully adjustable, easy to wire in, works with A/C, and can have a seperate toggle if you like. TBI car fan is independant from the computer, so that's why I asked - you can use a seperate fan controller with no computer issues if you ever decide to try that route - they run anywhere from $35 to over $100 depending on the bells and whistles.

I not saying you need one, just offering my experience. But 220-230 is not unusual i these cars.

 

what does the dam look like? I was looking under and there doesnt seem to be anything that would force the air into the rad

 

Should be black plastic, bolted right under the radiator, about 4 inches tall, about 3 ft across maybe. It'll be right under the radiator. It actually doesn't force air into the front of radiator, but creates a low pressure are behind the radiator - this low pressure area creates like a vacuum effect that draws air in through the radiator.

 

so, I do have the air dam, and I have switched out the rad cap. next step would be the thermostat. but after replacing the rad cap, the coolant still boils in the reservoir. the temp gauge went up to about 260 degrees. so that has me worried. any ideas?

 

260's the majic "don't do it, if you have don't do it again" number. Sounds to me like a cloged radiator. Try flushing it but I dought that will get it done at this point you may have to take it to a radiator shop to get cleaned out, or get a new radiator if it is clogged. Pull the cap off and see if it looks real crusty you will see what looks like scales growing in the radiator and possibly nasty looking coolant.

~Couch

 

I haven't seen any mention in this thread yet about what the fan is doing through all of this. Is it even working, and when? Sounds a little like PO had a fan problem and possibly removed thermostat ?

 

yea it is working. Im gonna check again in a bit, just to be sure, but yea last time i checked its running.