ok i have a sbc thats been bored .60 over, i have a 4 core radiator a flexfan and trans cooler and the motor keeps overheating up to 260 im told that 350 are supposed to run about 220 or lower, what should i do?

 

How long does it take to get so hot? Is your coolant full(any leaks)? Do you have a fan shroud? If not then how far away is the fan from the radiator? Do you have a clutch fan? Is your thermostat opening up? These are just a few questions that might help run down the problem?

 

Is your radiator cap good. The system needs a certain about of pressure to work properly. Keeping it under pressure raises the boiling point.

 

ok the car still overheats i made a fan shroud and put on it and yes it is a good cap, i can drive the car for maybe 15min then it starts rising if i get on the highway the temp still wont go down at first i thought maybe it was a bad temp sending unit but its not u can see the car pump water up into the overflow, i do have a good water pump and a good raditor since its been bored .60 over could this be why its still overheating, ive seen some stuff at autozone u can put into the radiator to help control the heat it says it can take it down about 40 deg is this just a scam and do u think it would work?

 

Try a new thermostat.

 

you still have the air dams under the front of the car on right?

 

Radiator caps are sold by pressure rating. Make sure you have the right one.

 

60/40 water/coolant mix?
Air dam installed?
Fan clutch working or locked fan?
Fan rotation correct?
Fan shrouded and close enough to the rad?
IIRC... 16 lb-per rad cap?
Thermo installed correctly?
Thermo operating?
W/p operating properly?

Any rad obstructions?
Tranny temp excessive with tranny cooler obstructing rad?
Lower rad hose collapsing?


There are two checklists for you. Top should all be yes, bottom should all be no. Have you taken alternative and independant readings?

 

60/40 water/coolant mix?

i thought using more water dropped your temps? im currently running just distilled water with 2 bottles of water wetter, would it run cooler with more coolant or some antifreeze?

 

I doubt the antifreeze will make much difference. Straight water has worked fine for me, cooling wise. Not good for corrosion prevention, obviously.

 

After you've verified you have the right radiator cap (16 lb non-vented is my favorite) and you have the right water pump (designed for rotating the way you're rotating it), it's time to rent a cooling system pressure tester from AutoZone.

Use the pressure tester to check your system integrity...pump it up to 16 psi and it should hold it for ~2min or whatever.

 

Try checking the thermostat housing. I recently had similar issues and it ended up there was alot of cr@p causing the thermostat to bind. Cleaned it out and power flushed the entire system. I also clipped about 1/2" inch off the thermo spring, thus lowering the relief temp (no stores nearby at the time). Never went back to replace the thermo, never had a reason to .

 

ok i removed the thermostat it seemed to run a little cooler and i checked and i did take the air dam off the car when i was striping it could replaceing this make a huge diffrence, ive taken the front bumber support out too, my car currently dosent have a hood either, but ill replace that air dam and get back to yeah, and i checked the cap its a 15 lbs cap should i change that.

 

Get that garbage off of it. Put a real fan on it. Electric would be best.

Make sure your air dams are all intact; the one that goes below the radiator, and the ones on either side, in front of the radiator, and the one up on top all around the hood latch. They make a great big duct to force air into the radiator. With any of them missing, air will bypass the radiator, and the rad won't get cooled. Yes, replacing it (and all the other pieces) will make a HUGE difference.

Then put the thermostat back in.