The Stovebolt Site Forums The Shop Area The HiPo Shop Still Running Hot!

The new GM crate 350/330HP in my 52 Burb is still running hot in traffic. The truck does have AC...we've added a 2nd electric pusher fan in front of the AC condenser...the condenser sits about an 1 1/2" in front of the radiator(per GM specs). I've even added some of that super cool liquid to the coolant mix. Truck runs up to about 230 degrees with both fans running when in traffic...cools right down on the highway.
Any ideas about potential causes/fixes? Anyone know what temp a new crate motor should run at?
How much CFM of cooling do you need for a motor this size?
Any help would be appreciated.

Hi Steve-

I've been playing with the same problem with my AD for awhile too I don't get up to 230 but anything over 200 bothers me.

Since your heating up in traffic and cooling down going down the highway I'm thinking you have a lack of air flow at idle but with two fan's going I can't see that being the problem. Now at higher rpm your also spinning the water pump faster and moving more water so that could also help the cooling. Do you have any type of high flow thermostat or water pump installed? I added a Stewart high stage II pump unit to my small block and knocked down the temps close to 10 degree's. It also takes longer for the fan to finally kick on so I know the pump has helped. Are you running a distributor with Vacuum advance?

hello steveg. this is a real long shot ,but it seems like you have all the obvious things covered with your cooling problem. so i will mention this. some of the later model water pumps are reverse flow to accomodate the serpentine belt setups. maybe you could check to be sure your pump is spinning in the right direction

Are you using a fan shroud? I believe they are available for these trucks from after market suppliers.

Thanks for the responses...couple of answers: I do have a GM serpentine belt system with a new/stock GM water pump...the main electric fan has a shroud on an aluminum radiator...the thermostat appears to be stock (but I'm not sure)...
I figure I've got to be putting 3500 cfm of cooling into that radiator...that should be enough to cool a jet engine!
Couple of other ideas: Could I have a temp gauge malfuntioning (because the motor is not overheating)? Could there be poor air flow in the engine compartment with no place for the superheated air to go?

Get one of those laser thermometers and start checking out your cooling system. Check various spots on your radiator and block for temperature differences. If everything is below 200 degrees, you probably have a guage out of calibration. Don't aim that laser at the exhaust, it will never work again.
Just a suggestion,
Scott

Have you run it with the radiator cap off to see if there is good flow when the thermostat opens? You can also put a thermometer in the radiator to see how hot it really gets and monitor the temp. when the thermostat opens.

Is this an electric sending unit? If so, maybe it is not grounded properly to the block if you used teflon to seal.

I lot of times those electric fans don't work well because they don't use a shroud and only cool the area the fan is actually over, near nothing compared to the size of the rad.

If your burb doens't over heat doing done the highway, but only in slower traffic it HAS to be the fans and or air routing, period. At speed the fans and or shrouds are doing NOTHING. So they are not the problem when it over heats at speed (thirty five or so and higher). At slow traffic speed or stop and go traffic, the radiator is relying TOTALLY on the air being forced thru it by the fans.

So, that being so, your fans need some sort of shrouding (or toss them and go back to a good old fan on the motor).

Think about what a shroud does. It FORCES all the air being sucked or blown by the fan THRU the the entire area the shroud covers. SO if you make a shroud that covers the entire radiator your fans are then cooling the whole thing instead of just the area the fans are hitting now.

Of course, how "NEW" is the motor has something to do with it as well. The new tighter motor is going to run a little hotter than a broke in one.

You also have to pay attention to how much area there is for the air to get out of the engine compartment. If you have headers, A/C, and other goodies under the hood with the stock inner fenders that were designed for a narrow six cylinder motor, you may not have enough air excaping the engine compartment. The air going in is MATCHES the air going out. SO if you have poor air flow out, the intake will be just as bad.

Well...we solved the "running hot" mystery. I'm very embarrassed to say that the cooling fan rotation was reversed and it was "pushing" rather than "pulling" air through the radiator. Never even considered that...we were looking for something more exotic. Stupid...so obvious...that we never even considered or checked it.
We reversed the rotation of the fan and we go to and stay at 180 ...highway or traffic! Lesson learned...start from the beginning and walk through the basic, common sense functions of the cooling system...9 times out of 10 you'll solve your problem. Thanks for all the valuable imput...

Steve, go to the Lounge and read my post from 6/5/04. You won't believe it. Yes, I had the same situation with the same outcome. Leason learned. I couldn't believe it when I read yours. Good luck.
Ron