my01camaroz28

iTrader: (15)

I have a 95 firebird formula with 113,000 miles on it. It has a new thermostat, water pump, radiator hose, temp switch, temp sending unit and yet this thing is still overheating. On the highway it is well under normal temperature, but on the city streets and at idle it over heats everytime. I have a bad ac system right now and the second fan isn't coming on. Is my fan or fans the problem or do I have a bad head gasket? I have no oil in the antifreez or coolant in the oil. What could be the problem?

WhiteLTone

iTrader: (18)

jump the ac relay to get the fans to turn on and see if that cures your problem..

HBHRacing

1st off the AC relay has nothing to do with fan operation. Igore that.


Was the corect thermo used?
was it bled correctly? (be 10000% sure you understand what the correct way is)
do you have a bag or other debris clocking the radiator? (look under the car)
Do you still hva ethe front air damn on teh car and working?

Aside from that stock fan on temps are 227 and 235.

CONVERTED

iTrader: (1)

what do you consider overheating???

These motors intown depending on the outside temp.. will run about 220ish.. you will have problems pulling timing at that temp however it's normal...

I do know first hand your air dam is probably the biggest thing you should check if it's total messed up and unable to supply enough air are asking for heat... also bleeding is something most forget. there are plenty of motors out there that dont' require such efforts after replacing tstat etc... these do... do a search for bleeding coolant and you should find step by step on how it's done... Air bubbles= hot spots.

NXSLT1

If it's gonna overheat due to the air dam missing or damaged then it would overheat more on the highway than sitting still. Took me forever to figure that one out on an 84 TA I had several years ago. Did you put a stock t stat in or a cooler temp one?? Like said above these cars are designed to run 220 or so for emissions purposes. We need to know what you consider running hot to be able to help you out.

goodestuff

I think I found the problems. My overheating is 260+ degrees and in the red with antifreeze boiling. I did some tests and my number one fan is week, number two is strong. Problem is they are not turning on now. I jumped the relays and got them to come on. So I am replacing the relays and swapping the number 1 and 2 motors for the fans since my ac is currently not working. I will get a new one later. This should cure most of the problem. My air dam is fine and there are no obstructions in, on, or around the radiator.

NXSLT1

No fans equals hot motor. Glad yer gettin it figured out.

CONVERTED

iTrader: (1)

weak fans' shouldn't cause that much of a problem... i'd be curious if it's bleed right.

NXSLT1

He said they aren't coming on now. Sittin still without a fan will heat it up pretty fast, same with the around town driving. It's possible it could need bleeding too but it would more than likely heat up on the highway too if that were the case.

my01camaroz28

iTrader: (15)

Found other problems. Look at the other thread I have called "cooling issues". It explains what is going on now. I replaced the relays and nothig changed. Both fans work fine but either the pcm isn't sending the signal because it is jacked up or there is a short in a wire somewhere. I blew a few trying to check it. I hooked an autoxray scanner and read the real time data from the pcm. At 220 degreas the pcm was showing that it didn't command the fan to come on. So I think there may be more than one problem. There could be a short in the wire that has burned out part of the pcm, thus two problems. Or the pcm is just bad and not sending the signal telling the relay to close and turn on the fans. I don't know. Please look at the other thread, there is more details in the testing there. I dont know what I need to buy right now and I don't have the proper wiring diagram yet. I just ordered the dealer manuals for the car.

dhdenney

iTrader: (53)

I had a fan out and I had the same problem as you. I just had to replace the fan motor. Put a voltmeter on your wires and if they're good, then replace the fan motor or the whole fan however the combo is sold (I can't really remember).

NXSLT1

I think stock settings are 226 and 235. If you have a stock tune then it won't tell them to come on at 220. Did the fans work before and then just quit all the sudden?

my01camaroz28

iTrader: (15)

Yeah they just stopped working, but where are you resourcing the 226 and 235? I have the radiator boiling at 220.

NXSLT1

Shouldn't be boiling at 220 unless you have a bad radiator cap. I looked at a few stock files in tuner cat is where I got those temps.

my01camaroz28

iTrader: (15)

I found the problem. The two month old fan switch went bad. Replaced it and all is well.

HBHRacing

a fan switch should have nothing to do with yours not coming on stock. Where did you get it?

my01camaroz28

iTrader: (15)

How can the fan switch have nothing to do with the fans not coming on? They send the signal for the computer closing the circuit. The temperature sensor tells just that. The temperature sensor told the gauge what the temp was, the fan switch, which is in the water pump, wasn't closing the circuit for the fans or ecm. It was the problem. Everything works fine now.

HBHRacing

very easily. Because there is no such thing as a fan switch. A fan switch is what people use to describe an actualy switch that is used to trigger the fans. What you are talking about is called a COOLANT TEMP SENSOR. It's a thermistor that sends a voltage signal to the PCM which is translated into motor temp. Perhaps you should correctly name the components so people do not take you for meaning something else.

my01camaroz28

iTrader: (15)

The car has a coolant temp sensor and a fan switch. This is also how it is listed at Autozone. I am not going to get into a sruffle about this. It is fixed, the proper name was used according to the parts store, and all is well.

HBHRacing

there is no fan switch. There is a temp sensor and a temp sending unit. The sending unit is JUST for the gauge. The coolant temp sensor controls fan operation as well as playing a part in fuel control. There is no such thing as a fan switch on a 4th gen. #rd gen has a fan switch on the pass side of the block. We don't. the correct name is coolant temp sensor.