cooling temp gauge question

[brittken]

Need help. Just bought a 96 firebird 3.8 liter. I drove 250 miles home last night with the temp reading about 200. My temp gauge maxed out last night showing the car overheating the last 2 miles home. It started going back and forth erratically.. I pulled over to the side of the road and popped the hood. There was no sign that the motor overheated at all. Im thinking faulty gauge or sending unit. The ses light came on. I fired uo the car this morning and the gauge was not workin at all. I replaced the sending unit and the ses light went off. The car is still reading about 240 and bagan to almost max out again. I have removed the thermostat and boiled it in a pot of water to see if its defective. It opens at about 180 to 200 degrees. I checked the temp of the water with a meat thermometer. The have drained the coolant and it looks a little dirty and i plan on changing it. Im wondering if my cluster may just be going bad. My speedo is reading about 5 miles per hour less than im actually going compared to what my gps reads. The gps is very accurate. My air bag light comes on periodically as well. Can you guys point me in the right direction to fix this problem? Thanks

[ssms5411]

Re: cooling temp gauge question

I would see what codes are stored in the PCM that were thrown, then use a scanner to see what the car is really running. Also make sure you bleed the air out real good. Check to make sure the air dam is still on and is in good condition, check the front of the radiator to make sure there is nothing sticking to it like plastic bags or other debris. You can also wash the radiator fins out with high pressure washer to get any dirt build up off of it. Might want to run green coolant with a 70/30 distilled water or just run 90/10 more distilled water than coolant. I run straight distilled water with 2 bottles of RP ICE ,so it still has lubrication for the water pump. It gets hot in AZ. You could get a 180 thermo and a manual fan switch($65) , I have that also. Theres also a bigger stock radiator thats 1 1/4" thick($125) better than the stock 3/8ths thick radiator. Finally RK sport makes a lower air dam to pull up more air its about $100 and I would also check you water pump, the fins on it could have been rusted away an its not circulating the water, the heater core could be clogged and the water is not circulating. If you have dexacool get rid of it and put in green coolant, I flushed mine a couple of times out and put in green coolant safe for all antifreezes just in case some dexacool was left in there. Good luck.

[transamtom1]

Re: cooling temp gauge question

If the system is not bled of all the air you will get erratic temp readings.

Put in a new sensor and flush and bleed the system.

[Green94Maro]

Re: cooling temp gauge question

If the system is not bled of all the air you will get erratic temp readings.

Put in a new sensor and flush and bleed the system.

How are you supposed to bleed the system?? Is it relatively easy?

[brittken]

Re: cooling temp gauge question

ok im in the process of flushing and bleeding the system. I have let the car run for 10 min waiting for the thermostat to open up. The temp gauge only reads a little above 160. I decided to put the car in gear to drive around the block. As soon as i did this the temp gauge started climbing to 230 240 250 on up in a 30 second span It pegged in about 45 seconds and the check gauges light came on. Again no signs of boil over and the fans are operating as they should. My airbag light came on again this morning also. I am waiting for the car to cool down to drain the cooling system again. The radiator is clean with and air dam is intact. Im starting to lean to a bad cluster. Any ideas?

[cam98aro]

Re: cooling temp gauge question

a bad cluster wont cause your check gages light to come on if it overheats

it does sound like you have air in your cooling system, i would bleed it by turning the little screw on the thermostat housing until the coolant runs out with no bubbles

[ssms5411]

Re: cooling temp gauge question

I would say bad water pump or clogged heater core. Something isn't letting the water flow through the radiator to cool down the water back into the engine.

[brittken]

Re: cooling temp gauge question

Ok the hose at the thermostat housing is hot. The lower radiator hose is cool. If the coolant was circulating shouldnt the hoses be about the same tempature?

[ssms5411]

Re: cooling temp gauge question

Yes, the lower should be hot as well if not hotter since its the hot coolant that has just came from the engine. The top hose is the water from the radiator and when the thermo opens it should be cooler than the lower hose. I would check the water pump or there is something clogging the coolant , maybe the heater core is the prime suspect.

[brittken]

Re: cooling temp gauge question

I removed the radiator hoses today and flushed the radiator. When i went to put the lower hose back on the radiator i noticed a piece of rubber stuck inside the radiator outlet. I pulled it out and it looks torn. It is about 8 inches long and i believe it was contributing to me cooling issues. The temp gauge is still reading hot though. My heater still only blows out cool air but I know Im getting flow now. Any idea where the rubber came from? Does the inner radiator deteriorate over time getting rubber stuck in the cooling sytem? Any help will be appreciated.

[ssms5411]

Re: cooling temp gauge question

If you had a piece there , who knows you might have some in the engine passenges or heater core, need to have it backed flushed to make sure nothing is blocking coolant movement.

[brittken]

Re: cooling temp gauge question

I pulled the radiator today and noticed some more rubber at the top of the radiator by the radiator cap. I pulled out the rubber from the radiator. I dont know what it is. It is not dry rotted and has alot of elasticity. The radiator shop said it might be part of the gasket that attaches the plastic side tanks of the radiator to the coils. I did flush the heater core and there is no blockage. I am having the radiator checked in the morning.