4.2 Fan Clutch Replacement with Pictures - Chevy TrailBlazer, TrailBlazer SS and GMC Envoy Forum

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OEM Issues Original Equipment Repairs and/or Problems

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Old 07-30-2011, 12:55 PM
Bowhunt_Pro's Avatar
Bowhunt_Pro Bowhunt_Pro is offline
2005 Chevy TrailBlazer LS
Monterey Maroon Metallic 4.2L I6 4X4
Join Date: Mar 2009
Location: Big Buck Ohio
Posts: 251
4.2 Fan Clutch Replacement with Pictures

Hi All, With reading various threads and searching down a problem of my own I noticed there wasn't a good thread on fan clutch replacement with pictures. I did read a lot of posts and people were complaining about this being the worst job they have ever done and it's really not all that bad.

Tool List:
1 7/16" Wrench
Torque Wrench (Suggested)
3" Extension
10 MM Socket
13 MM Socket
Hose clamp pliers or Channel Locks
Long pry bar (Optional)

Notes to remember:

Be careful maneuvering the fan clutch and shroud near the radiator. You can easily damage the delicate cooling tubes in the radiator if your hit them.

When reinstalling the fan clutch to the water pump make sure you thread it on by hand to start and keep it properly aligned while threading. The threads on both the water pump and fan clutch are very fine and easily damaged.

Wash off all spilled anti freeze prior to starting your vehicle. Failure to do so will cause the serpentine belt to slip and squeal.

Top off anti freeze when complete allowing the engine to run, thermostat to open and air pockets to burp.

Comfort and ability to do this job: Low to medium
Time to complete: 1 Hour.

#1 Before renting or buying a bunch of worthless specialty tools. Hit your local tool supply store for this wrench. About $12 at TSC.

#2 Removing your radiator upper core support. 8 Bolts 6 13MM and 2 10MM. A couple different views.

#3 Remove upper radiator hose. They make a specialty tool for the spring loaded hose clamps, however a good quality pair of slip joint (Channel Lock) pliers work fine. Rinse down your spilled anti freeze with water!

#4 Disconnect electrical connector to fan clutch. A few different views.

Simple squeeze of the tab to release. There may be a lock clip to remove, mine didn't have one.

#5 Loosen and release fan shroud. THE FAN SHROUD IS NOT REMOVED YET! That will happen later! There are 2 10MM head bolts at the top corners of the shroud, Two rubber flaps on the sides. and the transmission oil cooler lines on the back face. The rubber flaps are just pushed on to (2) nipples on each side. The long pry bar helps reaching and releasing these flaps. The transmission cooler lines are clipped into the shroud another place to use a prybar to pop them out. When they are released push them down below their retainer.

This first pic is the same as the missing radiator hose. If you look below the neck you'll see one of the tabs where one of the 10mm bolts is fastened. The other tab is simply at the opposite end of the shroud.

The rubber flaps on the side of the radiator were impossible to get pictures of while the still assembled. So the following pictures show the left and right sides of the radiator with the flaps after the shroud is removed. If you look closely you can see the two holes in the rubber flaps where they attach to the tits on the fan shroud. The two tops of the flaps would be easier from above the truck reaching down. The two lower parts might be easier from below, reaching up. THESE ARE HERE FOR A REASON, PUT THEM BACK WHEN YOUR DONE!

The next couple of pictures show releasing the transmission lines from the fan shroud. Push the lines down below their retainer so the shroud will clear them when you lift it out.

#6 Loosen and remove the fan clutch from the water pump. This is where that 1 7/16" wrench and hammer come into play. Put the wrench on the large nut attaching the fan clutch to the water pump and 3-6 good hits with a hammer and the clutch loosens its grip. The clutch loosens counter clockwise, Look at the picture! After the initial grip is freed you can spin the fan and clutch off the water pump by hand. After its loosened completely push the fan clutch forward to clear the water pump and lift it up and over the top of the water pump pulley bolts.It can rest there until your ready to remove it and the fan shroud together. The fan is integrated into the fan shroud. THEY MUST BE REMOVED TOGETHER. See next step!

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Old 07-30-2011, 12:55 PM
Bowhunt_Pro's Avatar
Bowhunt_Pro Bowhunt_Pro is offline
2005 Chevy TrailBlazer LS
Monterey Maroon Metallic 4.2L I6 4X4
Join Date: Mar 2009
Location: Big Buck Ohio
Posts: 251
A few different views:

Fan pulled forward and lifted above the water pump pulley bolts.

#7 Removing the fan, fan clutch and fan shroud all as one assembly. This is pretty quick and easy. You should have the transmission cooler lines below their retainer, the fan removed from the water pump and resting above the threads and the water pump pulley bolts as previously mentioned.
There is a lot of wiggle going on here but this all comes out as a unit!
The best place to start is to lift the right corner of the shroud above the upper radiator neck. (Right side of car, left side from your view.) Once thats accomplished its just some maneuvering and everything will lift up and out as a unit.

Note: When reinstalling the shroud should should go down and in with the corner near the upper radiator neck being last! Be careful not to hit the radiator fins during removal or installation, damage to the radiator can occur.

#8 Seperate the fan clutch from the fan and the shroud. Pretty easy, unclip the wiring harness for the clutch from the fan shroud. Remove the 4 fan retaining bolts reverse to install. Tighten the 4 fan retaining bolts to 20 Ft. Lbs. when done. I feel that torqueing these bolts is a important step.Reverse all previous steps to reassemble the unit and reinstall into the vehicle.

#9 Reverse procedures to reassemble and install.

Be careful when installing assembly back into the vehicle not to damage the radiator. Take precautions to properly thread the fan clutch back onto the water pump. It threads on clockwise. Use the wrench and hammer with 3-4 solid blows to tighten. There is a torque specification for this however its not practical and it wont loosen once tightened.

Make sure coolant is refilled and thermostat opens.
If you took it apart put it together!

I take no responsibility for spelling, punctuation, missing steps or damage to your vehicle. DO this task at your own risk, this post was meant to be a guide nothing more.
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Old 07-30-2011, 04:30 PM
Me007gold Me007gold is offline
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Join Date: Dec 2009
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Subscribed, and printed. This is going in my Trailvoy articles binder. Will come in very handy when I do my efan conversion in a few months.
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Old 07-31-2011, 09:04 AM
Bowhunt_Pro's Avatar
Bowhunt_Pro Bowhunt_Pro is offline
2005 Chevy TrailBlazer LS
Monterey Maroon Metallic 4.2L I6 4X4
Join Date: Mar 2009
Location: Big Buck Ohio
Posts: 251
I'll be posting wiring diagrams and trouble code flow charts today
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Old 08-01-2011, 11:32 AM
enga enga is offline
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Traded in at 162.5K miles Chevy TrailBlazer LS
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Great write up. I did mine a harder way.

I protected the radiator by slipping in a sheet of cardboard between the radiator and the radiator shroud.
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Old 03-29-2012, 02:59 PM
wielder02 wielder02 is offline
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2002 Chevy TrailBlazer LS
Pewter Metallic 4.2L I6 4X4
Join Date: Oct 2010
Location: Havertown, PA
Posts: 16
Driving my 2002 TB (130K) right now sounds like I have two box fans mounted on either side of my headrest. After reading through most of these informative threads I have concluded that I need a new Fan Clutch.

The step by step instructions and pics are excellent but my question is... does it matter which part I order form RockAuto.com? There seems to me a significant price difference between the manufactures. Any advice on which part to buy would be helpful!

DORMAN Part # 622001 $126.79

FOUR SEASONS Part # 46024 $210.79

HAYDEN Part # 3200 $214.89

ACDELCO Part # 1540133 $272.79

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Old 04-21-2012, 12:20 PM
heb77 heb77 is offline
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2002 Chevy TrailBlazer LS
Indigo Blue Metallic 4.2L I6 4X4
Join Date: Nov 2008
Location: Rhode Island
Posts: 10
My 2002 Trailblazer fan clutch failed after 130,000 miles, so I put in an AC Delco #1540133 unit (made by BEHR) I bought on Amazon from shopacdelco.com for $220.94 plus $11.79 shipping - best price I found!

I went with the AC Delco part because I heard some negative things about other parts and I am already saving about $500 doing it myself.

The pictures from Bowhunt_Pro were very helpful.

A few installation tips:

1. I used a long pry bay and an adjustable wrench with a 1 1/2" x 30" PVC pipe for leverage and the nut came off easy. Make sure the pry bar is not making contact with the nut as it is very close in there.

2. The 2 rubber flaps on the sides of the shroud are held on by (2) L-shaped "studs" on the shroud - the upper stud has the "leg" turned up and the lower stud has the 'leg" turned down - knowing this will help you get the flaps off and on.

3. The new unit does sit about 1/2" closer to the engine and in my case this caused the fan to make contact with an A/C hose & power steering line clamp that is mounted near the bottom of the fan - what a noise! I shaved a little off the fan before I shut it down, so check that clearance. I just stuck a rod down there and hammered the clamp down to clear, maybe it got bent up somehow in the last 10 years.

4. After removing and then installing the fan clutch I found it easier to relieve the tension on the serpentine belt and take it off the alternator. This allows you to line up the fan clutch nut with the water pump shaft and turn the water pump pulley to thread it on, instead of trying to rotate the fan clutch/fan assembly which I found difficult to do and still keep proper alignment.

5. I didn't upgrade the PCM programming, the fan seems to operate fine, and the SES light went off on its own after about 25 miles and 3 starts.
2002 Trailblazer LS 4WD G80 3.73 gear 134,000+ miles. Bought new 7/31/2001.
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Old 04-25-2012, 11:27 AM
ToddMeister ToddMeister is offline
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2002 Chevy TrailBlazer LS
Red 4.2L I6 4X4
Join Date: Apr 2005
Location: Bay City, MI
Posts: 15
Thanks for the pics and writeup

Tackled this job last Fri nite along with the water pump and thermostat. 02 TB with 145K miles.

Fan clutch had failed, roared most of the time and started setting codes.

New thermostat installed, I removed the alternator which made the job much easier.

New water pump installed, old one was starting to seep a bit.

New belt tensioner also installed, bearing on pully was getting noisy.

New Hayden 3200 fan clutch installed.

Thanks for the pics and writeup, also other posts on the water pump, alternator and thermostat replacement.

Took about 4 hours or so to complete.
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Old 05-08-2012, 10:08 AM
98tsiawd 98tsiawd is offline
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Envoy SLT GMC Envoy SLT
Midnight Blue Metallic 4.2L I6 AWD
Join Date: Jun 2010
Location: Airdrie, AB
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Thanks for the write up, I will be attemping this on thursday. quick question do you recommend disconnecting the battery first? or is it alright to keep it connected while doing the work?
Thanks for the help
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Old 05-13-2012, 03:44 AM
megamaumee megamaumee is offline
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2002 Chevy TrailBlazer LS
Imperial Blue Metallic 4.2L I6 4X4
Join Date: Nov 2011
Location: Pollock Pines,CA
Posts: 4
fan clutch help

my fan clutch won't disengage and the SES light came on. Do I need to replace it?
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