car over-heating hardcore
Thread Starter
1st Gear Member
Joined: Mar 2004
Posts: 88
From:
car over-heating hardcore
anyone know why my 94 GT over heats when i have my AC on? Seems normal but its a real pain when its 90 degrees out and im on the highway as my car is about to over-heat. Please help.
5th Gear Member
Joined: Dec 2003
Posts: 2,883
RE: car over-heating hardcore
ha why did you pick the audio section to post this question? when you put the ac on, the engine is working a little bit harder. undrive pulley's would counteract the ac's strain on the motor, but it wouldnt help the overheating. check your coolant, and make sure its not low. hell, it prob wouldnt hurt to put new coolant in the motor. make sure the electric fans are working, and a bottle of redline water wetter would help as well.
edit* thread has been moved out of audio section
edit* thread has been moved out of audio section
3rd Gear Member
Joined: Jul 2004
Posts: 581
From: Livonia,MI
RE: car over-heating hardcore
Just a question.
Do you have underdrive pulleys?And if so did this problem start when you put them on?
The car should'nt overheat with underdrive pulleys,I'm leading somewhere else with so wait till he responds OK guys.
Rye
Do you have underdrive pulleys?And if so did this problem start when you put them on?
The car should'nt overheat with underdrive pulleys,I'm leading somewhere else with so wait till he responds OK guys.
Rye
6th Gear Member
Joined: Jul 2003
Posts: 14,917
RE: car over-heating hardcore
Changing coolant won't help any. Let me clear something up about coolant. Anti-freeze DOES NOT keep your engine cooler. You're better off running straight water than anti-freeze if your looking for cooler operating temperatures.
Driving on the highway with your AC on, regardless if it's on or off should give you cooler and much more optimal engine temperatures. Make sure your fans are kicking on & your thermostat is operating correctly.
Driving on the highway with your AC on, regardless if it's on or off should give you cooler and much more optimal engine temperatures. Make sure your fans are kicking on & your thermostat is operating correctly.
I ♥ Acer
Joined: Sep 2003
Posts: 8,826
From: United States
RE: car over-heating hardcore
To check your t-stat just wait till the engine is hot and the fans have already cut on (t-stat should be open by then) and feel the upper hose - it should be hard to sqeeze and hot. If your unsure then take the stat out and boil it in water and see if it opens. The main causes of overheating are, it the order of most common to least common (to the best of my ability):
stuck thermostat (check it)
water pump bad (doesnt have to be leaking to be bad, especially if dirty cooling system)
fan not coming on (check it)
dirty, corroded cooling system (power flush that baby)
radiator dirty and corroded (see cooling system)
air in cooling system (low coolant, just changed something in cooling system)
too much ignition timing
engine running lean
vacuum leak (causing lean condition)
Im sure theres more but thats all I can think of right now.
stuck thermostat (check it)
water pump bad (doesnt have to be leaking to be bad, especially if dirty cooling system)
fan not coming on (check it)
dirty, corroded cooling system (power flush that baby)
radiator dirty and corroded (see cooling system)
air in cooling system (low coolant, just changed something in cooling system)
too much ignition timing
engine running lean
vacuum leak (causing lean condition)
Im sure theres more but thats all I can think of right now.
5th Gear Member
Joined: Dec 2003
Posts: 2,883
RE: car over-heating hardcore
its not a bad thermostat...they are designed to fail open, if hes fine without the ac, the thermostat isnt going to magically shut when he turns it on. that can be ruled out. i say change the coolant. its prob old. put a 70/30 mix of water/antifreeze in since its summer. i just did this to my camaro, its running so much cooler, its almost to good to be true.
2nd Gear Member
Joined: Feb 2004
Posts: 431
From: United States
RE: car over-heating hardcore
If it's ONLY when the A/C is on it could be your A/C cooling fan isn't kicking on to provide extra cooling as it should. I remember reading something about this circuit recently and how to test it. I think it was in my Haynes manual but I'm not going to swear to it.
I ♥ Acer
Joined: Sep 2003
Posts: 8,826
From: United States
RE: car over-heating hardcore
He said it overheats on the highway, which eliminates any fan problems because you don't really need the fan to work when your at speed. I told you what "could" cause your problem, and while thermostats are "designed" to stick open, it actually doesnt happen that way much because the crud in the cooling system will coat the t-stat and raise the temp required to open it - often times above any temperature the coolant could ever reach. If your unsure about it then just replace it (costs all of 5 bucks) or throw it in a pan of boiling water and see if it opens.
Id say its either the t-stat, water pump, radiator, or cruddy cooling system. If the tstat don't fix it then powerflush the system (prestone makes a kit that taps into a heater hose - its sold at parts stores for cheap), then if that don't fix it then change the water pump.
Their are still other things that can cause that, like a blown headgasket or cracked head, etc. that could superheat the coolant (but not allow the coolant into the combustion chamber). You can do a compression check to eliminate that. Oh and yea even a bad radiator cap can cause overheating as well if its not holding pressure.
Id say its either the t-stat, water pump, radiator, or cruddy cooling system. If the tstat don't fix it then powerflush the system (prestone makes a kit that taps into a heater hose - its sold at parts stores for cheap), then if that don't fix it then change the water pump.
Their are still other things that can cause that, like a blown headgasket or cracked head, etc. that could superheat the coolant (but not allow the coolant into the combustion chamber). You can do a compression check to eliminate that. Oh and yea even a bad radiator cap can cause overheating as well if its not holding pressure.
2nd Gear Member
Joined: Feb 2004
Posts: 431
From: United States
RE: car over-heating hardcore
ORIGINAL: mdvaldosta
He said it overheats on the highway, which eliminates any fan problems because you don't really need the fan to work when your at speed. I told you what "could" cause your problem, and while thermostats are "designed" to stick open, it actually doesnt happen that way much because the crud in the cooling system will coat the t-stat and raise the temp required to open it - often times above any temperature the coolant could ever reach. If your unsure about it then just replace it (costs all of 5 bucks) or throw it in a pan of boiling water and see if it opens.
Id say its either the t-stat, water pump, radiator, or cruddy cooling system. If the tstat don't fix it then powerflush the system (prestone makes a kit that taps into a heater hose - its sold at parts stores for cheap), then if that don't fix it then change the water pump.
Their are still other things that can cause that, like a blown headgasket or cracked head, etc. that could superheat the coolant (but not allow the coolant into the combustion chamber). You can do a compression check to eliminate that. Oh and yea even a bad radiator cap can cause overheating as well if its not holding pressure.
He said it overheats on the highway, which eliminates any fan problems because you don't really need the fan to work when your at speed. I told you what "could" cause your problem, and while thermostats are "designed" to stick open, it actually doesnt happen that way much because the crud in the cooling system will coat the t-stat and raise the temp required to open it - often times above any temperature the coolant could ever reach. If your unsure about it then just replace it (costs all of 5 bucks) or throw it in a pan of boiling water and see if it opens.
Id say its either the t-stat, water pump, radiator, or cruddy cooling system. If the tstat don't fix it then powerflush the system (prestone makes a kit that taps into a heater hose - its sold at parts stores for cheap), then if that don't fix it then change the water pump.
Their are still other things that can cause that, like a blown headgasket or cracked head, etc. that could superheat the coolant (but not allow the coolant into the combustion chamber). You can do a compression check to eliminate that. Oh and yea even a bad radiator cap can cause overheating as well if its not holding pressure.
He's already been down the road of new water pump, new thermostat, new radiator cap, system flush (twice by dealer who was sure it was air in the system), etc. So he's left with radiator or flow problems.
As for JJ94GT, I tend to agree with MD. Start w/ the easy stuff. And work your way up.
You can also check your water pump pretty easy. Check your weep hole for signs of moisture. If it's starting to fail you should see moisture there. You can also check the flow through the radiator. Start with a cold engine. Start the engine and let it warm up some. Open your radiator cap and you should see a good flow through after the t-stat opens. If not...it's the t-stat or water pump.