Full disclosure: this is an 82 351w in a 47 ford truck with an electric fan that has a singe terminal temp sensor located in the thermostat housing. Motor has been slightly built with cam, intake, carb, and headers. All parts of the cooling system are new.

ive only had this thing on the road for a few months while I’m working out all the kinks. I typically drive it a few times a week for 15-30 min at a time. Twice now, I’ve been driving for 30 min plus and the temp has crept up to 230 (according to aftermarket gauge). One time the radiator overflowed/burped coolant.

Both times it’s gotten hot, it seems the electric fan has been running at about half speed and is going in/out. I replaced the temp sensor for the fan (located in thermostat housing) and the fan relay. I also replaced the 195 degree thermostat with a 180 degree thermostat.

Could the fan running weak/intermittently cause it to overheat like that? I assume so.

I checked all the electric/wiring on the fan and all seems to be good. It’s almost like there is hot water pulsating through the thermostat housing causing the sensor to read hot and make the fan run, then read cool and shut it off.

Could this be be a sign of a head gasket being installed backwards? There are tabs sticking out of the front of the heads, and I thought I installed the gaskets correctly, but there’s always a chance I messed up.

I’ve read that you can tell that a head gasket is installed correctly if there’s a tab sticking out of the front. I have tabs sticking out the front of mine but would like to confirm this is what I should see.

Drivers side




Passenger side

I’ve never been a big fan of aftermarket electric fans, but I’ll save that for another day.

A quick check for a problem with cooling airflow through the radiator: Does all seem good above 30mph? Does it heat up below that speed? Above 30mph or so, you’ve typically got good ram airflow through the radiator. That should help determine what’s happening.

Another quick thing to check. There’s a short 90 degree hose between the water pump and intake manifold. It’s super easy to kink this hose shut during installation. If pinched shut, it can cause general wonkiness with the thermostat behavior.

I also would prefer to use the factory fan but I didn’t have enough room in the engine bay.

Both times it’s overheated have been in slower traffic. In fact, same time of day at same location after similar drive times.

That 90 degree hose could be the issue.

I see there is a 90 degree bypass hose and a curved one. Is the 90 degree the one I need? I’m not sure which one I have but it didn’t make the angle all that well.

Does the radiator have a fan shroud? I’m other words, does the air have to go through the radiator via the fan? Or can the air flow through the radiator without going through the fan?

I don’t have a shroud on the radiator. Do I need to fabricate one?

Yes, you can research the effects of not having one.

Also, what side of the radiator is the fan mounted? And do you know if it’s a pusher or a puller?

Have you run it at night with lights in? Wondering if the lights dim while at idle and it’s not spinning as fast. Could be that your alternator at idle can’t keep up with the power need. Could be.

I’ve done my e-fan installs with the OE fan shrouds in mind.
or made sure the fan I used, had a sufficient enough stock shroud to cover the radiator.

You’ll find in some cases where people have used aluminum or tin, to cover any exposed parts of the radiator not covered by the fan.