72 clutch fan

[Jeff W.]

I have read that the fans should not rotate more than 3 to 5 times after engine shut off. Mine does not rotate at all when I shut the car off. Rebuild time? or is zero rotation OK?
Thanks

[Norm C.]

2 Related Additional Questions

Not to hijack Jeff's post subject,,as I believe both of these related questions will help Jeff as well.

1. If the fan rotates more than 5 times after shut off,,,,OR in Jeff's case, if it doesn't rotate at all.... what does that mean regarding a reduction in the clutch's performance??? I assume that means that the oil inside has lost some or all of its effectiveness and the fan is not turning at correct speeds depending on the defect??? Can someone enlighten us?

2. The previous postings on this subject highly recommended a vendor who was compared to John Pirkle as the "Pirkle for Fan Clutch's" (Have his name at home Jeff if you need it) I contacted him, and he is 6-8mos out for turn around. If John & I need his services.... what is a recommended replacement clutch to use/buy while ours is being re-conditioned? Obviously we would want to limit additional expenses,,,, yet not take any undue chances with engine heat!!

Thanks in advance to those who have gone before us.

[Harry Sadlock]

Re: 2 Related Additional Questions

That person being Fred Oliva at 954-755-1161.

http://www.gate.net/~foliva

I think the nest time to call is 10 to 2 on Saturday.

His current backlog is 4 months.

Harry

[Harry Sadlock]

Re: 2 Related Additional Questions

Thats Best Time, not Nest Time.

Need an edit feature......

[Jeff W.]

Re: 2 Related Additional Questions

I have an article by Joe Sikora, not sure where I got it off the net, and he details how to replenish the oil in the clutch. It sounds fairly simple and inexpensive. With a new aftermarket going for $130 and a complete rebuild at least $100, I just want to determine if rebuild is needed. Norm, thanks for adding to my questions and hope that we get some more response.

[Joe L.]

Re: 2 Related Additional Questions

Jeff and Norm-----

If the fan clutch rotates excessively after engine shutdown, it means that the fluid resevoir in the clutch is depleted and/or the clutch is otherwise worn. In this case, the fan is, essentially, "free-wheeling" and, effectively, "de-coupled" from the drive system at all times. That means that it won't pull much air.

If the fan clutch does not rotate after engine shut-down, that can indicate a good thing---that the clutch is just fine. However, I'd want to make sure that the clutch is not "frozen". In other words, you should be able to turn the clutch by hand after engine shutdown and it should be a smooth, no significant wobble sort of thing.

The best performing SERVICE fam clutch for 71+ Corvettes? That's easy---GM #88961768. It's not configured like the original clutch, but it will work far better.

[Jeff W.]

Re: 2 Related Additional Questions

Thanks Joe. I can freely turn the fan with no difficulty. I do not have any noise coming from it as well.

[Dick W.]

Re: 2 Related Additional Questions

Jeff, the article that Joe Sikora wrote was in the MAC Signal Seeker

[John daly]

Re: 2 Related Additional Questions

dick,
I found it on the Mid Atlantic Chapter website...it's the Spring 2006 Signal Seeker. very interesting piece.

[Gary Schisler]

Joe, it seems I have screwed something up...

because I cut and pasted your comment:

"The GM replacement (P/N 3916141) is still available, and is almost identical to the original"

and now I read the 88961768 is the best performing.

Do I assume that one is more correct looking, 3916141, while one is better performing, 88961768?

Did I copy a part number incorrectly for something other than my 72?

Sorry for the confusion.
Gary

[Dick W.]

Re: Joe, it seems I have screwed something up...

Gary, different bolt circle and pilot hole. 71+ water pumps have a larger shaft and bolt circle

[Gary Schisler]

Thank you for clearing this up. *NM*

[Joe L.]

Re: Thank you for clearing this up.

Gary-----

Yes, the GM #3916141 works for 1960 to 1970 applications only. It is very similar in appearance to many of the units originally used during this period. It's closer to some than others, but its GENERAL configuration is similar to most. It cannot be used for 71+, though, and it's not similar to the 71+ units, anyway.

The GM #88961768 is similar to SOME of the fan clutches used from 1974 to 1981. However, it's not similar to those used from 1971-73, although, functionally, it will work perfectly for 1971-73. There is no fan clutch available from GM today that is similar to the 71-73 units.

[Gary Schisler]

You cleared this up nicely, now I

will change my cut and paste file to reflect the information. I KNEW I had screwed it up somehow.

Thank you.

Gary