My 98 Trans AM is running hotter than normal. I have a 160 T-stat installed. On a normal highway cruise my gauge sits on or slightly above the 185 mark and never goes higher no matter how hot the air temp is. At the end of last year before putting the car away for the Winter I noticed the gauge climbing toward the red zone. I found a plastic bag was stuck on the front of the radiator. After removing the bag the car continued to run hot, gauge goes above the 210 mark. According to Autotap the real temp is in the 230 - 240 range. I drained the coolant and flushed the radiator clean. I installed 50/50 Dexcool and distilled water, still running hot. I tried all the coolant air bleeding methods, still running hot. On a hot day the fans would continue to run after shutting the car off.

This Spring with cool air temps the car is still running hot. I installed a new 160 T-stat, new radiator cap, red line water wetter, bled the air again and still running hot. Water is flowing in the radiator (0.25 inch in diameter) and both fans are working properly. After a drive all the radiator hoses are very hot. Also, the heater works fine and when on it helps bring the temps down a little. The front and back of the radiator are free of obstructions and the cooling fins are in good shape. After driving the car and getting hot the cooling fins are still as cool as when the car has sat overnight? Shouldn't they have some warmth to them? I also changed the oil and there is no evidence of antifreeze in the oil.

 

how many mile on the water pump ?

 

Have you noticed any antifreeze leaks? When this was happening on my T/A there was a very small crack in the radiator which leaked a very small amount but it was enough to screw everything over. New radiator fixed everything.

At this point though, the waterpump is definitely the next thing I would look at.

 

+1, sounds like your water pump is on its way out

 

Water pump is original. Owned car since new, only 29,000 miles and less on engine. No leaks.

 

Even new stats can function improperly bro. I'd try another thermostat before I replace my water pump.

 

Both thermostats are good.

 

With the drain valve open, a hose in the radiator flowing well and the thermostat open after idling for awhile, the car actually cools down when I raise the engine rpm's. With everything closed up normally the temp rises too high when increasing rpm. Does this indicate my water pump is not operating at full potential???

 

Bump - I also have this exact same problem. I switched my 180-degree thermostat out and put into a brand new 160-degree one. Same temperatures. My "Low Engine Coolant" light also comes on now as well after the temperature hits about 180 or so.

It runs cool for the first 15 minutes the car is running after a cold start. Then it heats up to the last white line on the temp gage, goes down to about the middle line then heats back up slowly and back down it goes after it hits the last white line. I'm not sure what those temps are.

I flushed the system, even upped the % of Antifreeze in the system, Nothing. I also think it could be my water pump and I'm going to be replacing it soon.

Update: Checked out the waterpump, works fine. Will be checking radiator for problems/leaks and be testing the temperature of my coolant.

 

any news to this problem?

 

Update 2: I checked my water pump, its fine. No obstructions or radiator leaks. But tonight I tried something new, I turned my climate **** to "MAX" and turned the temp **** to full heat and the fans on full. My car idled at the first white line and drove right in the middle of 2nd and middle line. I'm going to be replacing the fans soon and installing a fan switch. I don't think my fans are working at their full potential.

 

I hate to be the bearer of good news, but have any of you thought about the radiator cap? It sounds as if the coolant system isn't holding pressure or that there may still be air in the system. The guage will fluctuate like that with air in the system, the sensor heats up quick to hot air. Just another idea and route to take that;s cheap before big money is spent!