1971 442 convert

I am going to have to add some more air movement as I keep overheating after highway cruising. Runs around 180 to 195 at 50 and 60 mph, but once I slow up for traffic or have to sit at idle very long the heat just climbs.

I have been doing some research and know I may have to upgrade my alternator depending on the fan or fans.

I would like to go with a pusher, (so it still looks stock and I have tons of room up there), so what have you guys used or what do you recommend?

Thanks,

oldcutlass

What does your temp climb to?

1971 442 convert

220 plus and will boil over if I don,t just pull over in about 20 mins or so.

oddball

Pushers tend not to move as much air as pullers. Also, if you have A/C, you have to make sure the air doesn't just go around the radiator. Pushers tend to be used to augment the main fan. If you go that route, get as much power as you can, but then it makes a smart controller that much more necessary.

First things first, though: do you have a shroud? thermo fan clutch (that works!)? 6+ blade fan? Radiator in good shape?

chadman

As was said above, pullers work better. I used to have a similar issue to yours. It would run 180-185 cruising at 60mph. Sitting in traffic it would start to creep up. I ditched the waterpump driven fan and added twin 11" pullers. All good now.

1971 442 convert

No ac. new 4 core rad, shroud and 7 blade flex fan. This all got me to a better running temp at cruise speeds and even around town. It's when the motor is hot and I have to slow right down for even just a few minutes it just climbs in no time.

oldcutlass

People ahve had good luck with a dual Windstar van setup. Not super expensive at the junkyard.

matt69olds

Are you SURE all the correct shrouding and insulation is present and in good condition? On my 69, I used lots of extra tar paper (or whatever the splash shield that go around the control arms are made of) to make panels and shrouds around the grille,bumper and radiator. Whatever air enters the grille area has to go thru the radiator. It cant go under, around or over the radiator. I drove this car on several stops of Power Tour this past year, I could idle in traffic for hours on end and never get hotter than 190-195. On the highway at night it almost runs too cool, it will drop below 160. And get rid of the flex fan, get a 7 blade fan and the proper thermal fan clutch.

1971 442 convert

Yes correct shrouding is in place.

If I went with the thermal clutch fan route would the Hayden 2747 HD be a good option and what 7 blade fan would work the best?

I understand from the info on some threads that the closer the fan is to the rad the better the results. How close should the fan actually be? Right now I am about 3" away with the 7 blade flex fan.

Thanks for you input on this.

oddball

The fan should be located in the middle of the circular section of the shroud. The shroud needs to be as close as possible around the outside of the fan to be effective. Distance from the radiator only matters if there's no shroud.

Hayden 3619 is a stock replacement 6 blade and works well.
The clutch you found looks like a good one. It's funny how what used to be called "Standard Duty" is now the "Heavy Duty".

1971 442 convert

Thanks.

Any idea with the HD 2747 thermo clutch fan and the 3619 6 blade fan what the approximate CFM 's would be ??

Should I change my water pump at the same time?

oddball

I think the rating would be "lots".
I've never heard of any actual numbers associated with mechanical fans.

If the pump is failing or noisy, then sure. Otherwise, no need.

1971 442 convert

Thanks Oddball. Just hoping that this will be enough to do the trick.

johns59super88

If the car is generally stock and with proper shrouding, why would it be overheating? There must be a problem somewhere in the cooling system or in an area that could cause the overheating (head gasket leak for example). My philosophy is that GM designed the cars to run without overheating with stock equipment. If it is overheating, something is wrong. Extra fans, etc will just cover the problem, not resolve it. JMO as I'm just an old rookie at this.

oddball

The only issues I've had with the stock fan and shroud is running the A/C in stop-and-go traffic in Texas. Engine will creep up to ~200, fan clutch kicks in, sounds like an air boat. Not quite enough air movement to keep the condenser cool enough. But without A/C that's not an issue!

My hope is that the flex fan just wasn't up to the task. Highway cruising will raise oil temps from the sustained RPMs. But since you're going fast, there's plenty of air to keep the coolant at the right point. Once you slow down, the engine still has the heat load, so the fan needs to pull more air until the residual heat is pulled out. Flex fans just don't move much air - by design.

If the problem persists, then you're looking at maybe a water pump or thermostat problem, but fairly likely a slight head gasket leak or just corrosion build up in the block.