overheating?

[92BoostedDSM]

ok so im over heating pretty bad. first i replaced the thermostat and that didnt help. so next i replaced the radiator the new one i got was about 1' think were as the other was 1/2' thick. Now this helped alot but i start overheating under boost. If i driven slow and dont run it hard it dosnt overheat it only does it under boost. could the new t stat be bad after running it on the old radiator? im going to change it next. anyhting else i might look into this is a brand new 6 bolt motor with maybe 300-400 miles on it. im only running 10-12 lbs for break in.

 

[v8s_are_slow]

Get a 180 degree stat. Also, if you have slimline fans, make sure they're spinning the right way.

 

[Jeff99GS]

Try some stuff called Water Wetter It seems to work well to reduce temps!

Wire Both of your fans to a switch and turn them on all the time when its real hot out.

Buy a New Cooling system Cap...if the springs gets worn out it will not hold the proper PSI in the cooling system...That will make it get hot.

You can also Rent a Pressure tester from Auto Zone and test the cooling system and the cap!

 

[laserspeeddemon]

We'll what you guys are missing about the fans is he said the car overheats on full boost. That means the car was moving. The fans don't need to be on while the car is in motion, because the air passing through it at travel speed moves more air then the fans can move.

So the problem is not the fans. It can solve the sympton, but not the cause. Sounds like the coolant is not moving and causeing the car to overheat. Sounds like air in the coolant system or lack of coolant, perhaps a coolant leak. Lastly, it could be a faulty temp sensor.

 

[daren_p]

Some good info so far but also thought should add have you done a compression test just to make sure the headgasket is sealed properly, as you say its a new rebuild & only happens under boost?

 

[tsunari]

what exactly do you mean by over-heating? Is the stock gauge rising above horizontal or do you actually have a decent aftermarket gauge?

Things to check for over-heating:

• Coolant level (and air in the system)
• Proper Water/Coolant mix (Probably no less than 75% water / 25% coolant for max heat extraction)
• Working Radiator Cap (If the spring is weak, your system can not build pressure and will leak coolant into your overflow until all is lost)
• Proper Thermostat for your application (most likely should use a 180*F thermostat unless living in the arctic)
• Coolant leaks (These can be difficult to find, best is to use a leak tester that will pressurize the system)
• Proper tension on the water pump drive belt (How old is that water pump by the way . . .)
• Still have the ducting to direct air up into the radiator, or has that been torn off- it makes a HUGE difference
• When was the last time the entire system was flushed? (If it's not done annually or semi-annually, coolant passages can become blocked)

Could also check your coolant for any oil or dirty film . . . might be that the head is lifting under boost and super-heating the coolant . . . but once back in your garage . . . passes a compression test or leakdown just fine.

 

[crimsondragon]

When was the last time your water pump was replaced?

 

[92BoostedDSM]

im checking on the water pump, i bought this car as it sets. i assume the water pump is new but it may not be since everything on the motor is new. it has been flushed since its a new radiator and the fluid is clean when i check it. i only have a stock temp gauge it runs about halfway until i start boosting it hard then it rises but i haven't let it get past the mark yet. when ever it does it i stop and kill the car. its building pressure int he upper radiator hose and the over flow is spewing steam out of the hose and also you can hear the water boiling. i believe the t stat is a 190* as thats all i could find. i haven't replaced the cap yet but it seems fine. I have checked multiple times and cant find any leaks anywhere. haven't done a compression check yet. Car runs like a bat out of hell idles great and everything in between until i start boosting it a lot.

 

[Jeff99GS]

At atmospheric pressure (normal pressure) water boils at 210 degrees....when you pressurize that same water, the boiling point rises...meaning the water/coolant has to get hotter to reach a boil.
A Higher pressure = A higher boiling point....so your Radiator cap May "seem fine" but if its only holding 10psi instead of 14psi that will LOWER your Boiling point and make the car run hotter.

The Rad cap has a spring with a seal on it and when the spring or seal wear out they allow the Coolant to escape into the overflow bottle. And that Lowers the systems Pressure.... That means It will also lower the systems BOILING POINT or temp at which your coolant boils.

Same thing applies if you have a small leak somewhere like in a Rad Hose, Heater Hose, head gasket, Heater core or Radiator itself. If its leaking, it is also LOSING Pressure and letting in AIR...that will Make the car run hot also.

You need to do a pressure test on the cooling system and see what pressure it holds...Its real easy to do...you just attach the pressure tester to where the Rad cap goes!

 

[92BoostedDSM]

what is the exact pressure im looking for, im bout to go to town and go ahead and get a new rad cap and t stat. and i guess i can rent a pressure tester.

 

[jking29]

I believe Autozone has the pressure tester in their loan-a-tool program. Just leave a deposit and you get it back when you return it. If the cooling system checks out, a compression test is definitely next on the list.