GMCforum
For enthusiast of the Classic GMC Motorhome built from 1973 to 1978. A web-based mirror of the GMCnet mailing list.

Home » Public Forums » GMCnet » Fan clutch.
Fan clutch. [message #162137] Sat, 03 March 2012 19:58 Go to next message
rssbob is currently offline  rssbob   United States
Messages: 259
Registered: January 2004
Location: La Mesa, Ca. (San Diego a...
Karma: 0
Senior Member
I wanted to replace my fan clutch because my fan never stopped running or slowed down so I assumed it was stuck.

R\This is what I found when I disassembled it. There was no clutch, only this big hunk of steel.
http://www.gmcmhphotos.com/photos/showphoto.php?photo=43041&title=dsc01512&cat=3798

The next picture will show my finished assembly. Now I have a fan clutch. I also decided to replace the rad hoses and t-stat now that I am into it.


Bob Sobrito
78 Palm Beach
La Mesa, Ca
Re: Fan clutch. [message #162139 is a reply to message #162137] Sat, 03 March 2012 20:07 Go to previous messageGo to next message
roy1 is currently offline  roy1   United States
Messages: 2126
Registered: July 2004
Location: Minden nevada
Karma: 6
Senior Member
You must be running the stock final drive or the noise from the fan would have driven you nuts at say 3000 rpm. I just got home from a 1200 mile trip. The bearing in my fan clutch went bad near Las Vegas and the heat locked up the clutch. I at first thought I had a wheel bearing going bad but it turned out to be the clutch in the fan.

Roy Keen Minden,NV 76 X Glenbrook
Re: Fan clutch. [message #162147 is a reply to message #162137] Sat, 03 March 2012 20:57 Go to previous messageGo to next message
JohnL455 is currently offline  JohnL455   United States
Messages: 4447
Registered: October 2006
Location: Woodstock, IL
Karma: 12
Senior Member
Better stuck on than off in Las Vegas. I would think that off is the normal fail mode. Another PO mystery.

John Lebetski
Woodstock, IL
77 Eleganza II
Re: Fan clutch. [message #162189 is a reply to message #162147] Sun, 04 March 2012 11:35 Go to previous messageGo to next message
roy1 is currently offline  roy1   United States
Messages: 2126
Registered: July 2004
Location: Minden nevada
Karma: 6
Senior Member
JohnL455 wrote on Sat, 03 March 2012 18:57

Better stuck on than off in Las Vegas. I would think that off is the normal fail mode. Another PO mystery.



Only 60 this time of year when passing through


Roy Keen Minden,NV 76 X Glenbrook
Re: Fan clutch. [message #162192 is a reply to message #162137] Sun, 04 March 2012 11:46 Go to previous messageGo to next message
Ken Burton is currently offline  Ken Burton   United States
Messages: 10030
Registered: January 2004
Location: Hebron, Indiana
Karma: 10
Senior Member
Bob, I'm concerned that you might also have the wrong fan. With the correct fan and 100% coupling the noise should have driven you out of there.

Even the severe duty clutches that some people install on GMCs they only couple up at somewhere around 75% speed.

What does your fan look like?


Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
Re: Fan clutch. [message #162205 is a reply to message #162192] Sun, 04 March 2012 13:52 Go to previous messageGo to next message
mike miller   United States
Messages: 3576
Registered: February 2004
Location: Hillsboro, Oregon
Karma: 0
Senior Member
Ken Burton wrote on Sun, 04 March 2012 09:46

Bob, I'm concerned that you might also have the wrong fan. With the correct fan and 100% coupling the noise should have driven you out of there.

Even the severe duty clutches that some people install on GMCs they only couple up at somewhere around 75% speed.

What does your fan look like?


I know that most of the time a "direct drive fan" is used it is some kind of flex fan. But the picture doesn't look to be one:
<http://www.gmcmhphotos.com/photos/showphoto.php?photo=43042>

Bob, Is the fan full size? (If full sized, you'll have problems getting the belts around the fan... not enough space at the tips.)


Mike Miller -- Hillsboro, OR -- on the Black list
(#2)`78 23' Birchaven Rear Bath -- (#3)`77 23' Birchaven Side Bath
More Sidekicks than GMC's and a late model Malibu called 'Boo' http://m000035.blogspot.com
Re: [GMCnet] Fan clutch. [message #162209 is a reply to message #162205] Sun, 04 March 2012 14:37 Go to previous messageGo to next message
Steven Ferguson is currently offline  Steven Ferguson   United States
Messages: 3447
Registered: May 2006
Karma: 0
Senior Member
That is a stock fan.

On Sun, Mar 4, 2012 at 12:52 PM, Mike Miller <m000035@gmail.com> wrote:

>
>
> Ken Burton wrote on Sun, 04 March 2012 09:46
> > Bob, I'm concerned that you might also have the wrong fan. With the
> correct fan and 100% coupling the noise should have driven you out of there.
> >
> > Even the severe duty clutches that some people install on GMCs they only
> couple up at somewhere around 75% speed.
> >
> > What does your fan look like?
>
>
> I know that most of the time a "direct drive fan" is used it is some kind
> of flex fan. But the picture doesn't look to be one:
> <http://www.gmcmhphotos.com/photos/showphoto.php?photo=43042>
>
> Bob, Is the fan full size? (If full sized, you'll have problems getting
> the belts around the fan... not enough space at the tips.)
>
> --
> Mike Miller -- Hillsboro, OR -- on the Black list
> (#1)'73 26' exPainted D. -- (#2)`78 23' Birchaven Rear Bath -- (#3)`77 23'
> Birchaven Side Bath
> http://m000035.blogspot.com
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
>



--
Fathom the hypocrisy of a nation where every citizen must prove they have
health insurance......but not everyone has to prove they're a citizen.
Steve Ferguson
Sierra Vista, AZ
_______________________________________________
GMCnet mailing list
Unsubscribe or Change List Options:
http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist

Re: [GMCnet] Fan clutch. [message #162210 is a reply to message #162192] Sun, 04 March 2012 15:01 Go to previous messageGo to next message
rssbob is currently offline  rssbob   United States
Messages: 259
Registered: January 2004
Location: La Mesa, Ca. (San Diego a...
Karma: 0
Senior Member
Thanks Ken,

I can tell you this, when I had the engine cover off and running the engine, the wind would almost blow me over and the noise was deafening. When I got it smogged, the technician made it a point to tell me how loud it was because he removed the cover to make sure I had the correct smog stuff on the engine.

When I installed the fan clutch, from above, it all went together smoothly. I had to first put the blade inside the cowl, then insert the clutch assy. Had to bolt that together while laying on my stomach on the plywood, then attach the clutch to the pulley location, just like the manual for the 77 / 78 said.

I haven't started the engine yet because I am also replacing all the radiator hoses and the thermostat.

How would I check to see if I have the correct blade assy? It has 7 blades and fit up perfectly to the clutch.


On Mar 4, 2012, at 9:46 AM, Ken Burton wrote:

>
>
> Bob, I'm concerned that you might also have the wrong fan. With the correct fan and 100% coupling the noise should have driven you out of there.
>
> Even the severe duty clutches that some people install on GMCs they only couple up at somewhere around 75% speed.
>
> What does your fan look like?
> --
> Ken Burton - N9KB
> 76 Palm Beach
> Hebron, Indiana
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist

_______________________________________________
GMCnet mailing list
Unsubscribe or Change List Options:
http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist



Bob Sobrito
78 Palm Beach
La Mesa, Ca
Re: [GMCnet] Fan clutch. [message #162211 is a reply to message #162205] Sun, 04 March 2012 15:04 Go to previous messageGo to next message
rssbob is currently offline  rssbob   United States
Messages: 259
Registered: January 2004
Location: La Mesa, Ca. (San Diego a...
Karma: 0
Senior Member
Mike,

I never messed with the belts. I did the work from above by removing the engine cover. I unbolted the metal piece with fan attached and was able to snake it up and out. I did have to disconnect the radiator hose to make room for it but it came out with little difficulty. So the belts and pulleys remained in place and out of the way.



On Mar 4, 2012, at 11:52 AM, Mike Miller wrote:

>
>
> Ken Burton wrote on Sun, 04 March 2012 09:46
>> Bob, I'm concerned that you might also have the wrong fan. With the correct fan and 100% coupling the noise should have driven you out of there.
>>
>> Even the severe duty clutches that some people install on GMCs they only couple up at somewhere around 75% speed.
>>
>> What does your fan look like?
>
>
> I know that most of the time a "direct drive fan" is used it is some kind of flex fan. But the picture doesn't look to be one:
> <http://www.gmcmhphotos.com/photos/showphoto.php?photo=43042>
>
> Bob, Is the fan full size? (If full sized, you'll have problems getting the belts around the fan... not enough space at the tips.)
>
> --
> Mike Miller -- Hillsboro, OR -- on the Black list
> (#1)'73 26' exPainted D. -- (#2)`78 23' Birchaven Rear Bath -- (#3)`77 23' Birchaven Side Bath
> http://m000035.blogspot.com
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist

_______________________________________________
GMCnet mailing list
Unsubscribe or Change List Options:
http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist



Bob Sobrito
78 Palm Beach
La Mesa, Ca
Re: [GMCnet] Fan clutch. [message #162212 is a reply to message #162209] Sun, 04 March 2012 15:05 Go to previous messageGo to next message
rssbob is currently offline  rssbob   United States
Messages: 259
Registered: January 2004
Location: La Mesa, Ca. (San Diego a...
Karma: 0
Senior Member
Thanks, Steve. I think it is also.


On Mar 4, 2012, at 12:37 PM, Steven Ferguson wrote:

> That is a stock fan.
>
> On Sun, Mar 4, 2012 at 12:52 PM, Mike Miller <m000035@gmail.com> wrote:
>
>>
>>
>> Ken Burton wrote on Sun, 04 March 2012 09:46
>>> Bob, I'm concerned that you might also have the wrong fan. With the
>> correct fan and 100% coupling the noise should have driven you out of there.
>>>
>>> Even the severe duty clutches that some people install on GMCs they only
>> couple up at somewhere around 75% speed.
>>>
>>> What does your fan look like?
>>
>>
>> I know that most of the time a "direct drive fan" is used it is some kind
>> of flex fan. But the picture doesn't look to be one:
>> <http://www.gmcmhphotos.com/photos/showphoto.php?photo=43042>
>>
>> Bob, Is the fan full size? (If full sized, you'll have problems getting
>> the belts around the fan... not enough space at the tips.)
>>
>> --
>> Mike Miller -- Hillsboro, OR -- on the Black list
>> (#1)'73 26' exPainted D. -- (#2)`78 23' Birchaven Rear Bath -- (#3)`77 23'
>> Birchaven Side Bath
>> http://m000035.blogspot.com
>> _______________________________________________
>> GMCnet mailing list
>> Unsubscribe or Change List Options:
>> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
>>
>
>
>
> --
> Fathom the hypocrisy of a nation where every citizen must prove they have
> health insurance......but not everyone has to prove they're a citizen.
> Steve Ferguson
> Sierra Vista, AZ
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist

_______________________________________________
GMCnet mailing list
Unsubscribe or Change List Options:
http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist



Bob Sobrito
78 Palm Beach
La Mesa, Ca
Re: [GMCnet] Fan clutch. [message #162259 is a reply to message #162210] Sun, 04 March 2012 23:30 Go to previous messageGo to next message
Ken Burton is currently offline  Ken Burton   United States
Messages: 10030
Registered: January 2004
Location: Hebron, Indiana
Karma: 10
Senior Member
rssbob wrote on Sun, 04 March 2012 15:01

Thanks Ken,

I can tell you this, when I had the engine cover off and running the engine, the wind would almost blow me over and the noise was deafening. When I got it smogged, the technician made it a point to tell me how loud it was because he removed the cover to make sure I had the correct smog stuff on the engine.

When I installed the fan clutch, from above, it all went together smoothly. I had to first put the blade inside the cowl, then insert the clutch assy. Had to bolt that together while laying on my stomach on the plywood, then attach the clutch to the pulley location, just like the manual for the 77 / 78 said.

I haven't started the engine yet because I am also replacing all the radiator hoses and the thermostat.

How would I check to see if I have the correct blade assy? It has 7 blades and fit up perfectly to the clutch.



That sounds like the correct one. I know it has seven blades and if it just fits inside the fan enclosure then it is the correct diameter. When I was working with the engineer at AC Delco on defining the correct fan clutch to use on our GMCs I knew the correct pitch. That was at least 8 or 10 years ago and I have forgotten it now. My wild guess is the pitch was 2.5 inches but I could be wrong.

You are probably OK with 7 blades. Denny Allen originally gave me the pitch dimension and I later measured mine. It was the same.


Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
Re: [GMCnet] Fan clutch. [message #162309 is a reply to message #162259] Mon, 05 March 2012 20:01 Go to previous messageGo to next message
rssbob is currently offline  rssbob   United States
Messages: 259
Registered: January 2004
Location: La Mesa, Ca. (San Diego a...
Karma: 0
Senior Member
I will let you know what happens as soon as I fire it up.

On Mar 4, 2012, at 9:30 PM, Ken Burton wrote:

>
>
> rssbob wrote on Sun, 04 March 2012 15:01
>> Thanks Ken,
>>
>> I can tell you this, when I had the engine cover off and running the engine, the wind would almost blow me over and the noise was deafening. When I got it smogged, the technician made it a point to tell me how loud it was because he removed the cover to make sure I had the correct smog stuff on the engine.
>>
>> When I installed the fan clutch, from above, it all went together smoothly. I had to first put the blade inside the cowl, then insert the clutch assy. Had to bolt that together while laying on my stomach on the plywood, then attach the clutch to the pulley location, just like the manual for the 77 / 78 said.
>>
>> I haven't started the engine yet because I am also replacing all the radiator hoses and the thermostat.
>>
>> How would I check to see if I have the correct blade assy? It has 7 blades and fit up perfectly to the clutch.
>
> That sounds like the correct one. I know it has seven blades and if it just fits inside the fan enclosure then it is the correct diameter. When I was working with the engineer at AC Delco on defining the correct fan clutch to use on our GMCs I knew the correct pitch. That was at least 8 or 10 years ago and I have forgotten it now. My wild guess is the pitch was 2.5 inches but I could be wrong.
>
> You are probably OK with 7 blades. Denny Allen originally gave me the pitch dimension and I later measured mine. It was the same.
> --
> Ken Burton - N9KB
> 76 Palm Beach
> Hebron, Indiana
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist

_______________________________________________
GMCnet mailing list
Unsubscribe or Change List Options:
http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist



Bob Sobrito
78 Palm Beach
La Mesa, Ca
Re: Fan clutch. [message #162321 is a reply to message #162137] Mon, 05 March 2012 23:19 Go to previous messageGo to next message
jirongzhi is currently offline  jirongzhi   United States
Messages: 1
Registered: March 2012
Karma: 0
Junior Member
I don't know what you mean.
[GMCnet] Fwd: New part numbers for radiator hoses, was Fan clutch. [message #162592 is a reply to message #162309] Sat, 10 March 2012 10:39 Go to previous messageGo to next message
rssbob is currently offline  rssbob   United States
Messages: 259
Registered: January 2004
Location: La Mesa, Ca. (San Diego a...
Karma: 0
Senior Member
For those of you who have been following this thread. After completing the fan clutch install,195 degree t-stat and radiator hose replacement I fired up the coach yesterday. What a nice surprise when everything worked properly. After a very short time the terrible windstorm dissipated and the calm on the inside was restored. I idled it for about 20 minutes and the engine temp needle lifted off the peg to about the 1/4 position. Don't know how the PO could have enjoyed driving it with that "no-fan-clutch" pully.

Thanks to all who replied with suggestions and advice.

One more thing I found replacements for the radiator hoses from Carquest. These are for the 403 and I do not know if they would be correct for the 455.

Top hose is 20991 and It is a perfect fit with the correct bends that also keep it away from the fan belt and tucked up tightly against the floor.

Bottom hose is 22125 and does require cutting 1" off one end and about 3" off the other after which it fits perfectly and clears the fan belt also with lots of room. I determined what to cut off the Carquest hose by using the old hose as a pattern, placing the new one on top of the old.

How do we get these Carquest numbers added to the parts list?



Begin forwarded message:

> From: robert sobrito <rssbob@cox.net>
> Date: March 5, 2012 6:01:30 PM PST
> To: gmclist@temp.gmcnet.org
> Subject: Re: [GMCnet] Fan clutch.
>
> I will let you know what happens as soon as I fire it up.
>
> On Mar 4, 2012, at 9:30 PM, Ken Burton wrote:
>
>>
>>
>> rssbob wrote on Sun, 04 March 2012 15:01
>>> Thanks Ken,
>>>
>>> I can tell you this, when I had the engine cover off and running the engine, the wind would almost blow me over and the noise was deafening. When I got it smogged, the technician made it a point to tell me how loud it was because he removed the cover to make sure I had the correct smog stuff on the engine.
>>>
>>> When I installed the fan clutch, from above, it all went together smoothly. I had to first put the blade inside the cowl, then insert the clutch assy. Had to bolt that together while laying on my stomach on the plywood, then attach the clutch to the pulley location, just like the manual for the 77 / 78 said.
>>>
>>> I haven't started the engine yet because I am also replacing all the radiator hoses and the thermostat.
>>>
>>> How would I check to see if I have the correct blade assy? It has 7 blades and fit up perfectly to the clutch.
>>
>> That sounds like the correct one. I know it has seven blades and if it just fits inside the fan enclosure then it is the correct diameter. When I was working with the engineer at AC Delco on defining the correct fan clutch to use on our GMCs I knew the correct pitch. That was at least 8 or 10 years ago and I have forgotten it now. My wild guess is the pitch was 2.5 inches but I could be wrong.
>>
>> You are probably OK with 7 blades. Denny Allen originally gave me the pitch dimension and I later measured mine. It was the same.
>> --
>> Ken Burton - N9KB
>> 76 Palm Beach
>> Hebron, Indiana
>> _______________________________________________
>> GMCnet mailing list
>> Unsubscribe or Change List Options:
>> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
>

_______________________________________________
GMCnet mailing list
Unsubscribe or Change List Options:
http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist



Bob Sobrito
78 Palm Beach
La Mesa, Ca
Re: [GMCnet] Fwd: New part numbers for radiator hoses, was Fan clutch. [message #162594 is a reply to message #162592] Sat, 10 March 2012 11:41 Go to previous message
Billy Massey is currently offline  Billy Massey   United States
Messages: 916
Registered: January 2004
Location: Central Texas
Karma: 1
Senior Member

They are added, Bob.

Thanks for sharing
bdub


-----Original Message-----
From: On Behalf Of robert sobrito

... snip ...

One more thing I found replacements for the radiator hoses from Carquest.
These are for the 403 and I do not know if they would be correct for the
455.

Top hose is 20991 and It is a perfect fit with the correct bends that also
keep it away from the fan belt and tucked up tightly against the floor.

Bottom hose is 22125 and does require cutting 1" off one end and about 3"
off the other after which it fits perfectly and clears the fan belt also
with lots of room. I determined what to cut off the Carquest hose by using
the old hose as a pattern, placing the new one on top of the old.

How do we get these Carquest numbers added to the parts list?

... snip ...



_______________________________________________
GMCnet mailing list
Unsubscribe or Change List Options:
http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist



bdub
bdub.net
Previous Topic: heater wiring
Next Topic: Scanner
Goto Forum:
  


Current Time: Sun Nov 17 18:18:44 CST 2024

Total time taken to generate the page: 0.02842 seconds