Overheat after start-up

[videoedit]

Ok - here is my situation .. I have a '96 Firebird, 3800 automatic that I bought used w/ 65k miles. Late December '04, I had my thermostat replaced and system flushed, to fix an overheat problem. Recently, this problem has come back. I would start the car, warm it for a few minutes, then start driving. Withing a few minutes, the guage would start going to the 225 degree line. After pulling over and putting on the AC and vent (to make sure the fans would be on), it would stay the same. Then I would shut the engine off for a few, start it back up and notice the guage drop a little, until I started to drive. Then, it would go almost to the red line, until I "floored" the accelerator, then suddenly, hot air would blow out and the guage went back to normal operating temps. My mechanic checked for leaks, checked fluid levels, checked to see that the fans are working, no service engine soon would kick in, checked that airflow was OK, even checked for head gasket malfunction, and unfortunately, it doesnt replicate itself for him, its intermittent, and everything works OK. There is no white smoke coming out of the tailpipes, and it doesnt steam up like an overheat would. So what do you all think it could be???? Sorry for the lengthy post. Thanks! Jon

[ March 03, 2005, 11:00 PM: Message edited by: videoedit ]

[stence]

coolant temperature sending sensor?
its under the throttle body in the front of the engine, it costs about 18$, i think.
its very easy to remove and replace, takes about 3 minutes
its worth a try

[V8 Killer]

Check Coolant Level
Check Thermostat (Stuck Closed?)
Check Radiator (Cracked?,Blocked?)
Coolant Temp Sensor (Should Trigger SES Light)
Fan Operation (Fan Motor,Blades)
Check Water Pump (Leaks? Damage?)

Try using a Radiator Additive like 40 Below or WaterWetter...They helped me out over the summer.

[Coriya71]

My vote is for air in the coolant lines.

[Rob Bell]

Yeah check to see if yours uses the "special air bleed procedure", where you loosen that little plug by the thermostat to let air out. Not sure if 96's have it, but mine's an 02 and you have to bleed it. Otherwise air gets trapped and it'll overheat. You can look in the owner's manual, and I know mine has a warning sticker by the air cleaner.

[videoedit]

Let me ask you this - if there was air in the line, wouldnt this happen all the time? This doesnt happen all the time, and why would "flooring" the accelerator suddenly make everything OK? Like I said above, there arent any leaks of any kind, the SES doesnt appear at all and the fans are working properly. Thanks for the responses folks! Jon

[cboney2003]

At least its not heating up before startup, that would really suck! (Sorry, know this isnt helpful but i am intoxicated, u can [img]graemlins/slap.gif[/img] me)

[Turbo V6 Camaro]

I think you need a new water pump... about 30 bucks and about 1 hours or so to change it out.... if yo have over 80k miles its way over due to be replaced

[FlamespikeMST1]

i had the same problem, but you didnt indicate that you were leaking at all...but my problem was a front cover gasket... but im with viper on this one....most v6 fbodys have trouble with heating issues, most wont admit it but the majority of us do.
good luck

[Turbo V6 Camaro]

i say that because you siad the car cool down if you floor it...... all other problems the car would way overheat. but if the watper pump it shot the higher RPM's would let the pump flow more water and cool the car more....

if its not the water pump i'll send you 1$ with pay pal

[Coriya71]

Let me ask you this - if there was air in the line, wouldnt this happen all the time? This doesnt happen all the time, and why would "flooring" the accelerator suddenly make everything OK? Like I said above, there arent any leaks of any kind, the SES doesnt appear at all and the fans are working properly. Thanks for the responses folks! Jon

Because you do have coolant in the system. When you press down on the gas the air still cools the coolant. And also pushes the air to another point in the line.

[38fury]

That's odd my car does something similar, it won't get hot like that but sometimes the thermostat won't open until im at half to full throttle, when its really cold outside like 15 degrees the thermostat won't open until like 220, and it drops like a stone to 160. But i need to flush my radiator probably could use a new thermostat as well.

[Die Ford V8]

I agree with viper totally. although i dont think you are overdue for a water pump. i just changed mine at 160,000 but yes its like thirty bucks. i bet your fins on your pump are eaten off from the dexcool. my friend had the same problem with his 2002 s10 which used the same design (maybe different bolt pattern) of water pump. he changed the thermostat, heater core, radiator, and all the lines and when i saw that heat would blow and the temp would go down after he revved it, i thought water pump for sure.

he swapped it then and there and it has worked ever since. another thing to add is that the fins were gone on his pump. yes gone,

just swap it and you should be good. if there are no leaks and it was flushed recently and the temp drops with increases in rpm, its your water pump.

remember if you guys buy a thermostat to get the other gasket. there are two gaskets. one to seal the thermo and the other for the tube that bolts down and holds the hose.

[Die Ford V8]

Originally posted by stence:
coolant temperature sending sensor?
its under the throttle body in the front of the engine, it costs about 18$, i think.
its very easy to remove and replace, takes about 3 minutes
its worth a try

guys dont just replace crap to fix something and you shouldnt even post about it. start with the basics. what the hell is a temp sensor going to do to fix over heating? turn the electric water pump that he doesnt have into full gear? [img]graemlins/slap.gif[/img]

look to the roots of what might be the problem.

oh yeah, how do you blead the air out of your coolant lines [img]graemlins/slap.gif[/img] [img]graemlins/slap.gif[/img] [img]graemlins/slap.gif[/img] [img]graemlins/stickpoke.gif[/img]
you lines are going to have some air in them anyways. frothing from the water pump will create air bubbles. its not like hydralics or brake lines [img]graemlins/slap.gif[/img]

I will also mail you a dollar if it doesnt fix the problem?


we need people that understand cars to post, not people that will make random guesses about the entire system.

also give a senario and a reason why your "guess" is legitamate,

please please post from experience or total legitimacy.

thanks

[Rob Bell]

I would agree that if it was air in the system, it would probably do it all the time, and would have done it immediately after your coolant change. However, if you have the air bleed screw, it doesn't hurt to check. I would try that first, all you do is loosen the screw with the engine running (not too hot though) until coolant comes out. It's the highest point in the system so that's where any air will naturally go to. If that doesn't solve the problem, then you need to start looking at other stuff. With the age of your car the water pump very well could be an issue. Some pumps last 80K, some last 150K or more. But try the free fixes first before you start buying parts and tearing things apart.

You can also take your thermostat out and put it in a pan of water on the stove with a thermometer to make sure it opens at the right temp. I've done that before on questionable thermostats.

Those are your two freebies...after that you need to start checking things like the pump. But at least water pumps are a very easy fix.