Hot Rods SBC overheating...yes I've tried almost everything!

Sounds like timing or you have an air pocket in the cooling system.

1. Take the thermostat housing and thermostat off/ out of the intake manifold.
2. Observe the level of coolant/ water.
3. Top off the coolant/ water level until it overflows onto the intake manifold.
4. Re- assemble and test

 

I would bet "your" left nut you have air trapped in the block..

 

Your saying it has a flex fan. If it's a standard flex it's blowing air instead of pulling the air. You said the water pump is stock. That's reverse flow. If it's reverse the fan must also be reverse.

 

Did you plug the pump and manifold fittings or did you run a loop of hose to them? I've had some goofy things happen when they were plugged and not allowed to bypass.

 

I'm still waiting for the picture, which would show the "straight" fan blade and reverse rotation belt setup

 

It's an aluminum flex fan, 6 blade. I was add a picture after while.


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I will do this and see. So you're saying add the water to the intake and not in through the radiator, correct?


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Here are some pics, guys. I included one of the carb to show the vacuum advance hook up location.


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Electric fan in front of an engine driven fan? Whats with that? I'd ditch both of them and install a 6 blade steel engine driven fan.

Gary

 

I'm only surprised it don't run hot all the time

 

So this fan will not work regardless of how it's mounted? Also, the electric fan should be mounted as a puller I thought? Aren't they more efficient that way? I really do appreciate all the help guys. Please don't be harsh on me, here.


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buy a reverse rotation fan blade. Remove the electric fan.

 

So for a test, pull off the engine driven fan and use the electric puller and see if it overheats. If it doesn't overheat get the correct engine driven fan and ditch the electric.

 

Something like this?

https://m.summitracing.com/parts/de...ing-products&gclid=COn3qbO4yNMCFUqewAodLWgE5A


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That one might be a bit too agressive, I'd get a flex fan, or a clutch fan.

 

Or remove the mechanical fan, use only the electric fan, see how it does.

 

I'm surprised the fan blades haven't laid back at high RPM and hit anything. The blades on those fans are supposed to bend into a flatter airfoil at high RPM, but since yours is spinning backwards the blades are actually biting bigger chunks of air and pushing it towards the radiator. You put the right rotation fan on it, it's gonna be quieter and probably give you back a couple horsepower.

 

So I'm guessing the flex fan I have know is normal rotation?


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Correct ,and time it with a light.

 

Okay guys. I can't thank you enough. I've (believe it or not) ran into this problem a few years back on a 50s Chevy pickup I was building. It completely slipped my mind that the water pump on these newer models were reverse. You guys are lifesavers! Thank you again! I will find a different fan and check back in!


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I think I have a reverse rotation GM fan in my garage, waiting for the scrap man. Let me check when I get home tomorrow afternoon. Phil

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That would be amazing!!


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Don't forget a 16# cap

 

I will be sure to change that as well!


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you changed the intake manifold right? did you use the intake gasket set for the tbi engine? if so they could be on backwards, the stock tbi gaskets have blocked off rear coolant passages with very small bleed holes in them, flipped to the front coolant passage, severely restricts the coolant flow

 

I used gaskets for the older style SBC.


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