hey everyone. While reading some recent posts someone mentioned you should only be able to spin the mechanical fan one rotation without the fan clutch engaging. I can spin mine indefinitely by hand. Does that mean the clutch is gone? I see it spinning when the engine is running.
Thx

 

If the fan just freewheels after giving a spin then the clutch is definitely faulty. It shouldn't spin more than two turns; one turn is better.

Cheers
DD

 

Thanks Doug
i pulled out the trusty workshop manual and it seems to show mine as the "later" type. Because it's a 79 it seems to have some series 2 parts and some series 3. Is this test method of turning the blades the same for the later setup. I confirmed just now that i can spin both directions indefinitely

 

The 'early' type clutch is the one with a single bolt in the middle. Used on Series II (and maybe even Series 1) and early Series III....up until the plastic fan was introduced.

The 'late' type has the four bolts/nuts attaching it to the water pump.

The early type is a non-thermal clutch. It is designed to be firmly engaged until xxx-engine rpm is reached....at which point it slips.

The later type is a thermal clutch. It slips until xxx-temperature is reached.... at which point it firmly engages.

Anyhow, neither type should just spin freely when spun by hand

Cheers
DD

 

Hi and wait a second!

Just got confused and thusly signed up, so hello everyone.
What confuses me is that you say that the fan should _not_ turn more than, say, one turn and then "engage". The way I understand it (and so do my installed and spare thermal clutch) is that the fan should be
a. neither seized or almost seized
b. nor freewheel when you let go, like a bicycle wheel off the ground. (Thats what Doug means)
However, I can spin it indefinitely by hand. But: when I let go, it turns just over half a revolution until it stops because of internal friction. Anyway, as long as you don't overheat... why worry?

David

 

Simple solution - get rid of the mechanical fans... install electric ones like ALL the modern cars use. Saves small amount of HP and you can tell if they are working properly!

This is one modern upgrade that is not subject to discussion on its merits.. they work. Just be sure to have a shroud that covers the radiator.. also putting high density foam around any gaps that allow air to escape going through the radiator helps a lot.

 

Hi David

Yes, you should always be able to turn the fan by hand, and do so indefinitely. In other words, you should be able to turn the fan by hand 1000 times if you wanted to. And, correct, you don't want a seized clutch....one that is impossible, or nearly impossible, to turn by hand.

If you use your hand to give the fan a spin it should not spin indefinitely. It should spin no more than two revolutions before stopping on its own.

Sometimes a fan can be seen spinning freely (as in your bicycle wheel example) when the engine is turned off. That's a sure sign of a worn out clutch.

Typically you can hear a difference when a fan cutch engages (or disengages) as the fan pulls much more (or much less) air.

Thanks for helping to clarify and welcome aboard

Cheers
DD

 

Oh, I think it's very much subject to discussion !

It's a good upgrade....if the installation is proper (as you suggest) and you choose correct, high grade e-fans. I've done so myself on various cars with good results.

But 'simple' is in the mind of the beholder. There's deciding which fan or fans suit the application, fabricating the mountings for a sanitary installation, wiring the fans and relays, and, on many older cars, the need of upgrading the alternator to cope with the increased load. This is all 'simple' in the grand scheme of automotive modifications, to those who are accustomed to making modifications and have the time to do so, but not as 'simple' as simply replacing a fan clutch...which is a perfectly acceptable solution as well. Buy the clutch, install the clutch. Done deal. Forget about it for many years. That's what I call "simple".

On my own car I'm thinking about using X300 fans as pictured...but that's quite far down on the list at this point. There are other areas taking priority at the moment!

Cheers
DD

 

Nice looking setup.. looks similar to the fans used on the Camaro with the LT1. Those vents open at speed to allow air into the engine area....

I have dual fans from a Ford but no vents... temp is obtained from a probe in the radiator and it has an adjustable thermostat control... next project is to hook them up to the ECU for the fuel injection to control the fans separately with temp chosen.. AC has Trinary switch to turn on both fans with AC use. This system has worked since 1992
with zero problems on the fans.

 

Yup.


Different strokes for different folks. My lump has a pair of after market EFans of unknown etiology. Straight blades, shrouded, but no vents. The PCM manages them perfectly.


My Jeep is still on the original clutch and mechanical. coos just fine.


Caveat:


The yellow plastic fan that was on my 4.2 was crazed in cracks. Failure on the way.
So, beware.


And metal fans can fatique and toss a blade.or so. Messy. Harder to detect a flaw on the way, Age would bother me some.


Carl

 

I have the same set up with ford fans, but with no ECU.
Easy to adjust the thermostat, it mounted on the radiator shroud with the probe in the radiator via the top hose.
both fans are activated when the air is on.