New Fan Clutch

  • Parts needed: Hayden Automotive Fan Clutch Model #2780
  • Tools Needed: J 41240 & J 41240-5A
  • Tools Used: Large Adjustable Wrench & Cable with Loops on Ends. 8, 10, 12 13, 15, sockets and/or wrenches, needle-nose pliers, small flathead screwdriver. 

I bought a replacement fan clutch for Moby (my 2005 Yukon XL K2500 4WD powered by the 8.1 liter engine) about 2 years ago. This morning I finally got around to replacing it. I actually tried getting this done on Thursday but I didn’t have the right tools. In fact, even this morning I didn’t have the right tools but on Friday afternoon I purchased a better version of the the wrong tool. Yay me!

Why swap it out? Why wait so long?

Obviously, this was elective surgery and the original part had not failed. If that was the case I would have had to replace it back when I purchased the replacement part. No, I was simply upgrading the part from OEM to an aftermarket Severe Duty unit.

A fan clutch aids in pulling air over the radiator, a/c condensor, transmission cooler, engine oil cooler, power steering cooler, and any other items that may be in use on a particular vehicle. It is one of the key components in making sure a vehicle runs at the correct operating temperature. Like everything in life, there are options when it comes to a fan clutch; the options are basically how often and at (approximately) what temperature (ambient air behind radiator) the fan clutch “locks up” or engages, thus causing the fan to spin faster and draw more air across the radiator.

Per the GM shop manual, to remove the fan clutch two special tools are needed; the J 41240 and the J 41240-5A.

J-Tools diagram

Ya right.

Needless to say that neither of these expensive, specialty tools is in my toolbox. On Thursday I tried removing the fan clutch with just pliers and an old dog leash. That had the predicable consequence of failure. On Friday I bought a gigantic adjustable wrench for $15 bucks at Harbor Freight Tools in place of J 41240 and I went to Autozone to try and rent a J 41240-5A tool from them. Autozone did not have what I needed so I decided to try again this time substituting a cable for the dog chain.

It was not a pretty sight, and I thought that something along the way would break, however I am pleased to report that the operation was a success and during the subsequent test drive nothing fell off the truck or caught fire*.


Shroud and air intake removed. Cable attached using extra long bolt run through the alternator mount and ends attached to two bolts on water pump pulley.


Severe Duty Thermal Features:
Turns the fan 80-90% of the shaft speed when engaged.
Turns the fan 20-30% of the shaft speed when disengaged.
Used with deeper pitch fans. (2 -1/2° of pitch).
Land and groove design with 70 Sq. In. of working area.
Larger working surface provides cooler running and longer life expectancy.
Thicker body and deep finned faceplate dissipate more heat.
Can be used in place of many heavy-duty clutches.


*I did strip the threads on the engine side hub a bit – small potatoes since everything still went together just fine.

Cross-eyed kitty tales of woe

Last week we had some of the hottest temperatures of the year so far (97°F-102°F) and look who decided to go up in the crawl space above our house? The neighbor’s cat, Kiki. This should be no big deal as Callie Meowingbutts goes up there all the time (when it is cooler) and gets down without consequence – not this cat though! No sir! No way! This cat gets stuck*!

So, forgoing the air conditioner we have running inside (that can barely keep up with the sweltering temps) I head outside after she has been stuck up there for quite a while and begin the process of rescuing her. She is panting and quite scared. The air coming out of the roof vents feels like it is 130°F or more. I feel genuinely bad for Kiki and want to get her down.

I remove the vent as carefully as I can (it’s totally fucked up now) and try and coax Kiki to come out. She is scared but at least she isn’t running away and hiding; she just stays right on the ledge. I tried pulling her out for a bit before Applesauce said she’d would pull the cat out. Up on the ladder Applesauce goes and after a few minutes she has the cat in her hands and is coming down the ladder. Kiki hits the ground running and is gone under the fence and then up and over another fence heading back to her yard.

Damn cats.



*Of course, by “stuck”, I mean too fucking stupid to go back out the way she got in.