Hey guys,
This weekend while driving around town my '89 Firebird started to overheat badly. As I was driving it home, the gauge fluctuated a few times from around 260 back down to 220 and then shot back up. Once home, when I popped the hood I could hear popping and gurgling noises (almost like popcorn). Finally, I noticed what looked like slightly greenish/brown fluid dripping a bit by the passenger footwell. The fluid was on the carpet up near the firewall, and dripped down along the plastic panel that comes near the door.
Now the water pump is one year old, the radiator less than 5, and the fan and engine temperature sensor less than 2 years old. Also, the coolant level in the overflow tank is fine.
Any suggestions on what this could be? I found a few posts mentioning the heater box, could someone better explain what/where that is and if it could be at fault? What I find most strange was the temperature flucuations while driving, which made me think of a blockage.
Thanks for any help.

 

Your leak on the passenger side floor sounds like the heater core is shot and needs to be replaced. Mine did the same thing last year.If your temps have been ok until now, check to make sure your fans are still working properly. If they check out your next step is to replace the thermostat. Check the tech boards on how to access your heater core, it`s behind the dash on the passenger side.

 

When your heater core core blew, there went some coolant in your system. Now your low on coolant to keep the engine temp down while driving.

Replace the heater core & you'll fix both problems.

 

and your heater core is above your feet in the pass. compartmant

 

Thanks there. I'm going to by pass the heater core inlet/outlet with some 1/2 inch copper tubing and alligator clamps until I get it fixed. Getting those hoses off was near impossible, I ended up cutting then instead and will have to get new hoses. There was some gross yellowish slime in them too.

 

Your gonna hafta get the cut hose end pieces off.....

The holes in the firewall for the heater core tubes to pass through, aren't big enough for the hoses to pass through too, still on the metal tubes.

 

Just did this last week too. Had to cut one of hoses also. After the bypass did you happen to notice anything different about your car? The way it felt, sounded, drove, etc.?

 

Thanks for the replies guys.
So I ran the car in my driveway today for 20 minutes, occasionally revving the engine to see if the loop would hold. The loop seemed pretty good, with maybe a very slight leak. However, I noticed another problem- the electric fan would not come on when the engine reached 220, and after about 20 minutes the engine reached ~240/50 at which point I turned it off. The fan never came on, except when I turned on the interior heat/AC. As soon as I turned that off, the fans cut off. So the fan motor works, but I think that one of the engine coolant sensors is also bad. This surprises me as I had a similar problem 3 years ago, where one sensor and the fan motor were both replaced. Maybe it is the other sensor, or the same one went again.
Thoughts on this now?

 

So from reading it seems most likely that is the coolant temperature sending unit (Hayne's term), which is located on the passenger cylinder head. Some here said it is better called the Radiator Fan Switch. My question is, while searching for the part- what is the difference between (AutoZone, couldn't find anything from Napa):

sw500: http://www.autozone.com/autozone/cat...archText=sw500

and sw505:http://www.autozone.com/autozone/cat...archText=sw505

Also, how do you know if the Engine Coolant Sensor (SU109?) is a problem?