Fan Clutch debacle, manufacture information

[Turbo4whl]

And I've always gotten both the thermal and the rpm actuated fan clutches. Since our Summers are so hot I'd rather the fan break loose when it gets hot than it just keep pulling slow traffic. Wait...I think I've got that mixed up some how. Let's see...I forget what's the temp clutch do? I know the viscus fluid will allow the fan to break loose at about 45 mph so it doesn't keep pulling when it doesn't need to. what does the temp spring do? damn.

Yes, backwards. The thermal clutch locks when the temp rises. Need more air at idle in traffic.

 

[SirRobyn0]

Most of the time I've gone to Pep Boys to get fan clutches. They have a better choice of better quality stuff there. But, my heart is broken because they went out of business and there was no one to take their place here in this two horse burg. So I'm left to getting stuff at Advance Auto Parts. But more than likely I'll buy off the web from some speed shop than auto parts store. I'd rather pay a little extra to get good American made parts I know are built to hold up as they are more than likely are race quality parts.

And I've always gotten both the thermal and the rpm actuated fan clutches. Since our Summers are so hot I'd rather the fan break loose when it gets hot than it just keep pulling slow traffic. Wait...I think I've got that mixed up some how. Let's see...I forget what's the temp clutch do? I know the viscus fluid will allow the fan to break loose at about 45 mph so it doesn't keep pulling when it doesn't need to. what does the temp spring do? damn.

Yes, backwards. The thermal clutch locks when the temp rises. Need more air at idle in traffic.

The canned answer is that non-thermal fan clutches disengage with RPM only, so they behave similar to a flex fan in that they won't pull air at higher RPM. For me that's not an option, to many hills and passes. At least a once or twice a summer I'll pull a flex fan off a classic because the owner installed it and brought it in not understanding why their rig gets hot on hills.

Thermal fan clutches
Standard duty unlocked turns 20 - 30% of shaft speed, locked 50 - 60%
Heavy duty and severe duty unlocked 40 - 50% of shaft speed locked 70 - 80 for heavy 80 - 90 for severe duty. Severe duty has larger fins as well.

My observations though the years this is not squares only, but applies to all vehicles. Standard duty does not turn enough fan speed unlocked for sufficient A/C operation in some vehicles. You will not hear a standard duty, you might hear a heavy duty, and most likely you'll notice the severe duty when it locks up, but because the severe duty turns a higher speed unlocked it's going to lock up less. Some fans mainly in cars with low pitch and less blades in the fan may not create enough wind resistance to unlock a severe duty fan clutch as much as it should be unlocked. What I'm talking about really is when cold. As you probably know severe duty fan clutches will be locked up on initial start up because of the heavier oil which has thickened and settled into the working area of the fan clutch over night.

Fan clutch manufactures state that heavy and severe duty fan clutches operate nearly, or actually the same (depending on manufacture) but the main difference is the working area, fins, and amount of fluid, making the severe duty clutch last longer. I disagree with this based on experience, it seems that the severe duty clutch pulls more air both locked and unlocked, again no scientific testing just what I've observed.

I know this sounds dumb but if you haven't already...I would verify that you have the correct fan and clutch. The fan should have GM part# on it. Serpentine systems that are reverse rotation started appearing in the 80's on these trucks and I've seen many people swap parts from other trucks not realizing they are using a reverse rotation fan/ clutch in place of the standard one.

My fan is the original equipment 5 blade fan. I have considered upgrading to the 7 blade fan often found in the 454's but as long as my fan clutch is functioning correctly I've never had overheating issues even with the trailer so I don't really see the need. I think I'd rather add a factory electric pusher fan, but that would mainly be to help the A/C out in traffic when I'm on the eastside of the mountains in the summer and hit traffic. My A/C has been retro-fitted to R-134A and if you know about that stuff you know R-134A is not as efficient as the R-12 our rigs came with. We are lucky that the condensers on our rigs are large so they take to the change better than some of the cars of the 80's do. But still at slow speeds more air passing over the condenser should help. I do not want to go full electric fan, to replace the mechanical fan mainly because a mechanical fan will beat all but the biggest most expensive electric fans in terms of air flow under RPM such as on hills, with a trailer. But an added pusher electric would be nice.

 

[SirRobyn0]

Quick up date from me on fan clutch on the square and then a little fan clutch info on another vehicle.

So on the square I've got 2 years on my A/C Delco severe duty fan clutch and it has been great. I drive the truck a lot too, and tow a trailer and haul loads so that fan clutch gets it's fair share of use. Not sure there is much else to say but it's been working good.

On my Jeep and this will tie into manufacture info. A few years ago I went though something similar, where I went though a couple of severe duty Hayden fan clutches that were defective. It was right around the same time I was battling the same issue on the truck. So I ended up with a standard duty GMB fan clutch as the Mopar unit is long discontinued, which has worked as well as any standard duty fan clutch ever does which basically means fine, unless it's hot out and I'm running the A/C at lower speeds, basically when a good working fan clutch is most important... So today I took the chance and order a severe duty fan clutch from O'Rielly's for the Jeep. It's a Murray unit, which is just a rebranded Hayden unit. I drove it around a little bit this afternoon and it seems to be working just like it should. Better yet the A/C vent temps, and more importantly the engine temps are not creeping up at idle anymore.

So I just thought I'd give an update on my A/C Delco fan clutch on the truck and what's happening with my new Hayden unit on the Jeep.

For those that haven't read the thread the cliff notes are about 2 years ago I went though a number of defective Hayden fan clutches on my square, turns out at the time, Hayden had just moved most of it's manufacturing to Korea.

Interesting to note that my Jeep fan clutch was marked with Mexico being the country of origin, so maybe Hayden has moved at least some of it's manufacturing back to Mexico?