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WARNING: Service Manual Error (?) on fan bracket bolt torque
http://www.lostjeeps.com/forum/phpBB3/viewtopic.php?f=5&t=65885		 Page 1 of 1
Author:  msilbernagel [ Mon Mar 19, 2012 1:18 am ]
Post subject:  WARNING: Service Manual Error (?) on fan bracket bolt torque
Discovered this while replacing the fan bracket during a timing belt service.

The Service Manual on page 7-56 (p 263 of the PDF version, 2005) says:

2.8L DIESEL
(1) Assemble fan blade to viscous fan drive.
Tighten mounting bolts to 23.7 N·m (210 in. lbs.)
torque.
NOTE: The viscous fan and fan shroud must be
installed as an assembly.
(2) Gently lay fan and viscous drive into fan
shroud.
(3) Install the fan shroud to radiator mounting
bolt. Tighten bolts to 9 N·m (80 in. lbs.) torque..
(4) Thread the fan and viscous drive onto the fan
support and tighten nut using special tool 6958 spanner
wrench.
(5) Install cooling fan support to engine block (Fig.
38). Torque bolts to 149 N·m.(110 ft. lbs.).
(6) Install fan drive viscous clutch and fan assembly
(Refer to 7 - COOLING/ENGINE/FAN DRIVE
VISCOUS CLUTCH - INSTALLATION).
(7) Connect negative battery cable.

HOWEVER, page 7-19 (p226 of the PDF) has a table listing it at 35 ft-lbs.

.. about 2/3 of the way down the table: Cooling Fan Support Bolts | 49N-m | 35 ft-lbs |

It seemed pretty high (110) and when I felt the bolt stretch I went searching elsewhere and discovered it was supposed to be 35!

So, one trip down to the local (wonderfully stocked) hardware store to pick up two new bolts and all is well.

Glad I didn't leave half a bolt in the block, or strip the block threads!

Be careful - :frankie:

:wink: Mark
Author:  geordi [ Mon Mar 19, 2012 2:58 am ]
Post subject:  Re: WARNING: Service Manual Error (?) on fan bracket bolt to
This is why I NEVER use their torque specs, especially for just hold-down mounting bolts.

Torque to decently-snug (everyone knows their own body, so it will be a different feel) but I have never had one of my own bolts back itself out. I'd say I pull them to about 25-35 lbs or so. If you have to grunt at it, it is probably wrong.

I'm glad you didn't leave half a bolt in there either. You are lucky that wasn't into the aluminum cover like the tensioner - those scare me, b/c the aluminum is so thin and weak.
Author:  Lancer [ Mon Mar 19, 2012 4:41 am ]
Post subject:  Re: WARNING: Service Manual Error (?) on fan bracket bolt to
Thanks for this. I'll be installing the nylon fan and clutch in a few weeks as the weather picks up.
Author:  Drewd [ Mon Mar 19, 2012 9:49 am ]
Post subject:  Re: WARNING: Service Manual Error (?) on fan bracket bolt to
I feel guilty for not being as thorough when I replaced my water pump last month. I only torqued the camshaft sprocket bolts with a torque wrench and did everything else "good and tight" using my calibrated arm.

Service manual inconsistencies killed a friend of mine in April,1995. Her accident's investigation revealed the inconsistencies and probably saved many additional lives including mine. http://www.chinook-helicopter.com/maint ... 02_sof.htm
Author:  papaindigo [ Mon Mar 19, 2012 10:06 am ]
Post subject:  Re: WARNING: Service Manual Error (?) on fan bracket bolt to
Those FSM instructions make no sense in so many ways:
1. in the first place why remove the fan support at all as part of removal of the fan. I'll admit getting the fan nut undone is not that easy but with a 36mm wrench, a ca. 3/8" allen key in one of the 2 small fan support holes at about 4 o'clock so it locks against a fan support nut, and some sort of pursuader on the end of the wrench it's not that hard. Especially compared to removal of 4 "invisible" bolts.
2. the fan nut does not need to be tightened to the fan support, just spin it down until it stops and from there it self tightens. Special tool 6958 looks like it might could be used, in the 2 small holes on the fan support, to hold the fan support while the fan is removed but that tool alone cannot be used to tighten anything.
3. they have totally omitted how to get the fan/fan shroud into the engine bay including the tabs at the bottom of the fan shroud.
4. step (6) makes no sense since that action was already done in step (4)
5. assuming one did removed the fan support why on earth try to reinstall the support with the fan already mounted on it as implied by step (4)

I love this forum's posts that replace FSM gibberish with clear step by step instructions with pictures.

I'd pick on Jeep/Chrysler but I've seen way to much gibberish or just flat wrong manuals in way to many industries. From time to time I've wondered if one could create a viable company based on a business model of addressing this issue. Yes I know there are the Chilton and such manuals out there but they often just put out the same misinformation.
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