Fan clutch has whupped me
 

A few months back I was so proud that I used this forum and found my wimpy fan clutch that would free-wheel. I replaced it with the $49 Chevy style from the tech sticky. Bolted up OK, and seemed to cool better.

After several other cooling fixes, (radiator rod out, water pump, thermostat, water wetter added) I wanted to get more cooling at idle.

So I took out the Hayden/ Imperial #215157 (may be an Advance Auto Parts number) and replaced it with the #215158 which is listed as extreme duty. Now all the spec sheets say these will drop back to 20-30% of water pump shaft speed until the face of the fan gets to 170, then it starts re-coupling. The 215157 will recouple to 60% or so of shaft speed, the 215158 is supposed to be 80-90%.

The extreme duty clutch bolted on, and does move more air. I noticed that even at 50 mph my coolant temp on the scanner was 178-180 (I also had changed to a 180 stat). Pix of new clutch and oem original.

I decided to see how this new clutch was changing rpm, because did not hear change speed as it warmed up/cooled off.

Used a photo tachometer, and saw that fan pulley and fan blade tip were making same rpm (within 5%). Thought this might be a bad-outta-da-box, so swapped it out today. Tests showed the same "locked up" speed on both sides of the clutch ( as close as you care to be to a 2000 rpm fan with 150 degree air blowing through it ). Did tests at idle and 2000 rpm.

Had another oem used clutch handy (not my original), put that on to test the photo tach. As clutch warmed up fan dropped to a lower rpm, and the noise change was so much that I thought I had broken a belt or something. Photo tach showed 2:3 speed reduction at the particular temperature I was at. Went for a test drive, and coolant temp stayed at 189, five miles, 55 mph. Yet with extreme duty clutch it had been 8-10 degrees cooler.

I can't say that I ever heard the 215157 clutch ($49 Chevy) ever change speeds due to temperature, either. The extreme duty clutch provides extra cooling (good for off roading), but will be at a cost of mpg. Can't find the specs that would point out the differences for torque or power required to have the clutch "shift" gears, would assume that Rover engine just may not put out enough power thru the fan pulley to correctly operate the extreme duty clutch. There may be another clutch that would provide extra cooling, but still change speeds.

Thoughts? Experience with the $49 Chevy conversion changing speed?

Note: with oem used clutch, fan noise reduced to the point I could hear the Advance Auto replacement 2nd alternator (6 months) bearing starting to howl..... I swear that this truck has wifi and can read the posts...

I've had the 215158 on my '95 Disco for several years. I've never done the detailed measurements, but I do know it runs more often. I just put it down to the fact it's a HD clutch and haven't worried about it.

Mine does not seem to ever slow down. But I noticed on the Hayden/Imperial web site they have a new listing for a model specific to Land Rover v-8s, and Orielly Auto Parts has a stock number for it, I will try to see if I can get one. It looks like the HD clutch we both have. I suspect there must be some variations on the inside that impact the actual performance of the clutch. But from a factory standpoint, who would want to make 500 various size clutch units? I suspect that perhaps the fill level of fluid and even the viscosity of the clutch fluid may be used to provide variation beween some product offerings. That and the number of groves milled in the clutch disk, and perhaps the spacing between them. If that is what they did, they could cast a lot of similar size disks and control the parameters by changing the CNC machince programs. When you have devices with so few iternal parts, there are not a lot of ways to have multiple choices. The new Hayden number is 2991.

Can't complain about the cooling I am getting from the "8" clutch, it worries me about running fan at 100% (there have been posts on other sites about fan coming apart), plus fuel milage. But it was keeping coolant temp at or just below thermostat rating.

Yeah, I switched to a metal blade on my '95 when I installed the HD clutch, because of the blade disintegration reports. Didn't want to have to buy a new radiator. ;)

I knew about the Hayden clutch, Summit Racing has carried them for a while, but I've never used one. They have the same size blade mounting holes as OE.

Yep, OrRielly told me the new clutches are special order from Hayden, not stocked in distribution. Where did you get the metal fan?

It's an imperial, I think I got it at Advance. It's a little too big OD and I had to measure, mark and remove about 1/8" or so from the end of each blade.
Here's my DWeb post when I did it.
DiscoWeb Message Boards - View Single Post - Replacement Chevy Fan Clutch on D1

Fan clutch bad if turns more than a turn. Best way to check drive till hot then open hood and have someone cut off engine if fan keeps rotating more that 1 turn needs to be replaced. It works from temp of fan clutch so spinning by hand when cold doesn't always count.

RB - IMHO the cold spin test is also needed to indicate the capacity for the clutch to "lock up" - if no fluid, it will spin even when cold. You are correct that when warm, it should also not spin more that a certain ammount. Of course, what we are discussing here is going beyond that to deciding if a particular fan clutch is "working" properly, in my case the Chevy S10 extreme duty clutch will mount, operate, move a lot of air, but never slows down when warmed up. As you know, the great advantage of a fan clutch is that it changes the speed of the fan to a lesser rate when at normal operating temp, saving gas and water pump bearings. When cold or warm it couples at the higher rate. Of course, the high volume clutch would be handy with a spare fan to put on your truck if you were going sand hogging, etc., where low speed high rpm activity is common.

Yes, I need a new fan clutch too. I'm going HD as I don't mind the noise, I like that Severe name and will take any cooling improvements I can get. If I get the save the gas bug I think I can swap out later as it looks pretty easy.

And it's only right to fit a metal fan. Really, I don't want to trim a fan and I can't see that discoweb link..think it's down. Are there any other metal fan solutions? I heard an Imperial. I can do Advance, AutoZone or Pep Boys.

Here's what I posted on Dweb