Car is running too hot
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Registered User
Joined: Apr 2003
Posts: 745
From: FL
Car is running too hot
Well my car is running too hot, in the 220-240 range. It will get that hot while driving on the highway for 15 minutes or driving around town for a while. Its been like this for about 3 weeks now.
Back in January I installed a new cam and while I was doing that I installed a brand new water pump, new radiator cap, and new temp switch in the head after I got it back from the machine shop. A couple weeks ago I installed a new 160 degree thermostat but that didn't really help. Last Friday I flushed the coolant out, that helped a little but it still runs hot. I have to turn my heater on now sometimes to help the car from over heating. Any ideas what could be wrong? It used to run between 180-200. The airdamn is in place and in good condition. I have a mechanical fan. I think the radiator is the stocker but im not sure.
Back in January I installed a new cam and while I was doing that I installed a brand new water pump, new radiator cap, and new temp switch in the head after I got it back from the machine shop. A couple weeks ago I installed a new 160 degree thermostat but that didn't really help. Last Friday I flushed the coolant out, that helped a little but it still runs hot. I have to turn my heater on now sometimes to help the car from over heating. Any ideas what could be wrong? It used to run between 180-200. The airdamn is in place and in good condition. I have a mechanical fan. I think the radiator is the stocker but im not sure.
Registered User
Joined: Feb 2001
Posts: 469
From: Lowell, Ma
you might want to check the clutch on the fan, or while you are at it upgrade to an electric fan (you can get them on ebay for pretty cheap) and then just run a switch from the fan to the interior of the car so you can turn the fan on and off when you want to. thats also a nice option to have at the track when you want a little extra help cooling off in between passes.
is the radiator cap the stock piece or an upgraded replacement? sometimes that will have an effect on how well your cooling system pressurizes.
is the radiator cap the stock piece or an upgraded replacement? sometimes that will have an effect on how well your cooling system pressurizes.
Thread Starter
Registered User
Joined: Apr 2003
Posts: 745
From: FL
you might want to check the clutch on the fan, or while you are at it upgrade to an electric fan (you can get them on ebay for pretty cheap) and then just run a switch from the fan to the interior of the car so you can turn the fan on and off when you want to. thats also a nice option to have at the track when you want a little extra help cooling off in between passes.
is the radiator cap the stock piece or an upgraded replacement? sometimes that will have an effect on how well your cooling system pressurizes.
is the radiator cap the stock piece or an upgraded replacement? sometimes that will have an effect on how well your cooling system pressurizes.
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Joined: Mar 2000
Posts: 2,037
From: 51°N 114°W, 3500' elevation
The thermostat keeps a minimum temperature in the engine. It has nothing to do with the maximum temperature. Once the thermostat opens, it's open no matter how much hotter it gets. The max temp is controlled by the rad efficiency. Coolant is pumped through the rad and the rad removes the heat. Any number of things can prevent the heat from being removed.
- Coolant flow too fast or too slow through the system
- Rad not big enough to remove excess heat from a higher hp engine
- Rad tubes internally plugged preventing coolant flow through the rad.
- Not enough air flow across the rad. The engine fan only provides air flow at speeds below 30 mph. Above that and there's enough air flow from the vehicle moving to provide enough air to pull the heat off the rad.
- An automatic transmission has cooling tubes running into one side of the rad. An excessively hot tranny can put too much heat into a rad.
- A rad cap with too low a pressure. A typical car should have a 15 psi rad cap. This doesn't keep the engine from overheating but just raises the boiling point of the coolant so it doesn't boil over at lower temperatures.
- A blown head gasket can cause it to run hot. It would be putting hot combustion gases into the cooling system. Leave the rad cap off and run up the engine to get it warm. Is there steam or bubbles in the coolant?
How about a defective temp sending unit or gauge? Maybe it's not really running that hot.
If you know your water pump is working, you have a good rad cap, no combustion in the coolant and you have air flow across the rad, my suggestion would be to replace the rad.
- Coolant flow too fast or too slow through the system
- Rad not big enough to remove excess heat from a higher hp engine
- Rad tubes internally plugged preventing coolant flow through the rad.
- Not enough air flow across the rad. The engine fan only provides air flow at speeds below 30 mph. Above that and there's enough air flow from the vehicle moving to provide enough air to pull the heat off the rad.
- An automatic transmission has cooling tubes running into one side of the rad. An excessively hot tranny can put too much heat into a rad.
- A rad cap with too low a pressure. A typical car should have a 15 psi rad cap. This doesn't keep the engine from overheating but just raises the boiling point of the coolant so it doesn't boil over at lower temperatures.
- A blown head gasket can cause it to run hot. It would be putting hot combustion gases into the cooling system. Leave the rad cap off and run up the engine to get it warm. Is there steam or bubbles in the coolant?
How about a defective temp sending unit or gauge? Maybe it's not really running that hot.
If you know your water pump is working, you have a good rad cap, no combustion in the coolant and you have air flow across the rad, my suggestion would be to replace the rad.
Registered User
Joined: Feb 1999
Posts: 70
From: Quakertown, PA USA
Oveheating
I have had the same problem until I spent a bunch of cash and resolved most of it. When I went from a 305 to a cammed up 350 this led to overheating issues while in traffic and my fans were working.
- I replaced my radiator with a Summit Racing aluminum (made by Northern) which made a big difference in keeping temps low.
- A Stewart Stage 2 Aluminum Water Pump and 180 high flow thermostat and a switch to Peak Global coolant with distilled water.
I don't think you need to go to this extreme, but replacing the thermo with a 180 would help keep it cooler along with some Purple Ice or Water Wetter, when I ran a 160 with the old 3 core brass/copper radiator, my vehicle ran hotter than with the 180.
I would also check for air pockets while keeping the rad cap off and putting a meat therometer in the radiator cap neck to make sure that your gauge is correct as well.
- I replaced my radiator with a Summit Racing aluminum (made by Northern) which made a big difference in keeping temps low.
- A Stewart Stage 2 Aluminum Water Pump and 180 high flow thermostat and a switch to Peak Global coolant with distilled water.
I don't think you need to go to this extreme, but replacing the thermo with a 180 would help keep it cooler along with some Purple Ice or Water Wetter, when I ran a 160 with the old 3 core brass/copper radiator, my vehicle ran hotter than with the 180.
I would also check for air pockets while keeping the rad cap off and putting a meat therometer in the radiator cap neck to make sure that your gauge is correct as well.
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