Running Hot

[Dog House]

I believe I inherited a vehicle with a number of problems. When the car reaches 195 you would think you would have heat coming out the vents and the cooling fan would come on but I get nothing but cool air and no fan. The temp has been as high as 220 without the fan coming on and still blowing cool air. Is correct to assume the water pump is bad? I have already replaced the thermostat but that wasn’t the problem it still gets hot. At what temp should the fan be coming on and since mine isn’t at all what should I be looking at to repair it. Thanks!

 

[CAJUN C4]

I believe on a 89' the ECM turns the fans on but at exactly what Temp. I don't know.220F is really not all that Hot believe it or not. Maybe someone with an 89' can shed some light on this for us.Oh,Might check the Fan Motors and make sure they are OK.Run 12 Volts from the Battery to it (them) make sure they run.

 

[Dog House]

I'll check the motor I think I only saw one. I should still be getting heat at those temps but I'm not?

 

[92BlackVette]

A 1992 Corvette running at 220 is an everyday deal....

 

[ex-x-fire]

Are your heater hoses both hot? If only 1 is hot then the control valve is not opening( check for vacuum ) or heater core is plugged up.
To check the WP, take the rad cap off, run the engine til its warmed up, 195* & above, rev the engine & watch the coolant flow like a water fall. Do you think you might have air in the system? Is it man. or auto a/c heater controls?
The cooling fans might not kick on til 225-230*.

 

[Schrade]

At 195 you definitely should have hot air.

Put the heat on max, fan on high, and check with your hands the 2 hoses going to the heater core (at the firewall). Input hose should be pretty hot, return hose should be close to the same temp; maybe a little cooler.

If there's a bid temp difference, and no heat, you have blockage in the core, or no vacuum to the core valve as the others said.

If you just got this car, you should flush the coolant system with fresh water. Drain cool, and put the garden hose in EVERY hose you can find, till clear water comes out of a different hole every time.

 

[Dog House]

Hello all, the car is new to me and apparently has several issues to deal with. I'll check all mentioned above and also flush the system. I did notice when I changed the thermostat there was a bit of rust in the system. Wow I had no idea these cars run at such a high temp. When I drove it home for the first time about 35 miles the temp went up to 228 and scared the heck out me wondering if I would make it home. LOVE THE CAR THOUGH!

 

[Toms007]

Another thing about these cars is that they are bottom feeders....they suck in the cooling air from the bottom front. They can vacuum up all the junk on the road and deposit it between the AC condenser and the radiator. When I first bought my 94 I, like you, thought the car ran warmer than I thought it should. Well I went through all the normal things, like you, and even removed the shroud and radiator and cleaned all the junk out. It helped, but I learned that these cars can you hotter than "normal" cars and trucks.

 

[Dog House]

Well the fan finally came on when the temp reached 234 and cooled the engine rather quickly to 220 so I assume the water pump is working, as for the heat both hoses from the heater were equally hot but still no heat inside the car. The blower motor is running although I can not hear it change speeds and there is very little air flow in any position defrost, heat etc…

 

[ex-x-fire]

Ok now your getting somewhere. If you have manual heater a/c controls then the vacuum line that switches may be broken. The vacuum line should be near the distributor, through the firewall. Put a vacuum gauge on the line going to the heater control valve, just to make sure it is recieving it. You should see the heater control valve arm move when you switch it from hot to cold, a/c max. might close it also.
I would also remove the blower motor to check for any build up around the heater core, that might cause air flow restrictions. Mice can get it the darndest places.

 

[gmjunkie]

Ok now your getting somewhere. If you have manual heater a/c controls then the vacuum line that switches may be broken. The vacuum line should be near the distributor, through the firewall. Put a vacuum gauge on the line going to the heater control valve, just to make sure it is recieving it. You should see the heater control valve arm move when you switch it from hot to cold, a/c max. might close it also.
I would also remove the blower motor to check for any build up around the heater core, that might cause air flow restrictions. Mice can get it the darndest places.

There is a good possibility that the Vacuum Check Valve up around the intake manifold is broken or faulty,(Common problem,Easy fix!) or the plastic clip on the temperature blend door under the dash has broken and the actuator rod has fallen off!!
If it's the latter,It sucks to be you!!

 

[patrickj]

I would check and see if the heater core has been by passed and you have to make sure you get all the air out of the cooling system after the t-stat change.Also your fans are probably ground activated check the relays and the fan temp switch should be in the block left side middle.hope this helps

 

[surfer93]

The cooling fans come on at 228* and I gather you mean the fans at the radiator, not the blower.

Once the temp is over say 100*, you should feel heat from the vents, as long as the heat temp is set lower than cabin temp.
Check to make sure the heater core is not bypassed, common thing people do, be cause it is a MAJOR pain to replace. The hoses go into the firewall underneath and behind the radiator fill tank, look underneath the tank and if you see the 2 metal pipes sticking out, then it is bypassed.
Take out the radiator, including frame(easier than just the radiator) you will see grass, paper, etc in the fins, using low pressure water, blow it all out.

 

[Paddywhack]

The cooling fans come on at 228* and I gather you mean the fans at the radiator, not the blower.

Once the temp is over say 100*, you should feel heat from the vents, as long as the heat temp is set lower than cabin temp.
Check to make sure the heater core is not bypassed, common thing people do, be cause it is a MAJOR pain to replace. The hoses go into the firewall underneath and behind the radiator fill tank, look underneath the tank and if you see the 2 metal pipes sticking out, then it is bypassed.
Take out the radiator, including frame(easier than just the radiator) you will see grass, paper, etc in the fins, using low pressure water, blow it all out.

Surfer and others hit it dead on about being bottom feeders and sucking in everything to the radiator. Just got my radiator out this week during the rebuild and my goodness, I was shocked to see the amount of leaves and grass and trash packed up in there!

 

[chubbydog]

Had the same problem on my 89, the fan doesn't come on until around 230, no big deal there, but if the blend door actuator is not working that is a big pain.

 

[thford89]

i have a 95 corvette, it runs around 210-225 on idle. The fans do not kick on till 228 and thermostat is rated for 180. If you want it to run cooler kick on your AC. You can also put in a lower temp rated thermostat. i have seen on for 150 or 160 but it did not seem to make a difference in my car so i went back to OEM.

 

[Tedmag1]

with the air on the fan should ron continussly with it off it should come on automatticly around 229 and then drop down to 209

 

[Tedmag1]

you could also empty your raiator and put in a special mix used for race car 50-50 MIX and it will run around 200 car will still run good but the stuff available at any auto parts store is VERY EXPENSIVE

 

[gmjunkie]

i have a 95 corvette, it runs around 210-225 on idle. The fans do not kick on till 228 and thermostat is rated for 180. If you want it to run cooler kick on your AC. You can also put in a lower temp rated thermostat. i have seen on for 150 or 160 but it did not seem to make a difference in my car so i went back to OEM.

Thats completely Normal!! Thermostat won't make any difference on how hot it will get!!

 

[Dog House]

Thanks for all the input, putting the car away for the winter today and will be dealing with this issue in the spring. Actually need to fix the drivability problem first, she's got a miss like you wouldn't believe, been working on it through my post (More Problems code 32) . 39 degrees in Minneapolis today and expecting rain and or snow. Happy Holidays All!!!