| Fan Shroud questions [message #163105] |
Thu, 15 March 2012 20:20  |
midlf
Messages: 2212
Registered: July 2007
Location: SE Wisc. (Palmyra)
Karma: 1
|
Senior Member |
|
|
I'm pulling the radiator and fan shroud off my front clip and am somewhat intrigued by the way GMC did this. On my 75 Vette the fiberglass fan shroud extends back over the fan, with some clearance between the fan blade tips and the shroud, enough to get a fan belt past. On the GMC, as most of you are aware, the fan "venturi ring", is mounted to the engine with a very tight clearance to the fan blades. This is an expensive method, parts and assembly time, compared to some of the alternatives used by GM.
My question(s):
Why did the GMC MH use this method?
Was it the method used on the Toro?
What is the purpose of the tight tolerance between the fan and the venturi ring? Noise reduction? Fan efficiency?
Just curious.
Steve Southworth
1974 Glacier TZE064V100150 (for workin on)
1975 Transmode TZE365V100394 (parts & spares)
Palmyra WI
|
|
|
|
| Re: [GMCnet] Fan Shroud questions [message #163106 is a reply to message #163105] |
Thu, 15 March 2012 20:30  |
Kosier
Messages: 834
Registered: February 2008
Karma: 1
|
Senior Member |
|
|
Steve,
They started out with a bad shroud design.(didn't cover the whole
radiator.) Then they did the "band-aid" job with the
venturi ring. And created a nightmare for the service man. The
later shroud is a much better design, And when you
split it, it works even better. Of course, you will want to run
the tranny cooler lines over the bellhousing and up the
left frame rail. Dropping the lower half of the shroud makes a
lot of jobs easier.
Gary Kosier
----- Original Message -----
From: "Steve Southworth" <midlf@centurytel.net>
To: <gmclist@temp.gmcnet.org>
Sent: Thursday, March 15, 2012 9:20 PM
Subject: [GMCnet] Fan Shroud questions
>
>
> I'm pulling the radiator and fan shroud off my front clip and
> am somewhat intrigued by the way GMC did this. On my 75 Vette
> the fiberglass fan shroud extends back over the fan, with some
> clearance between the fan blade tips and the shroud, enough to
> get a fan belt past. On the GMC, as most of you are aware, the
> fan "venturi ring", is mounted to the engine with a very tight
> clearance to the fan blades. This is an expensive method,
> parts and assembly time, compared to some of the alternatives
> used by GM.
>
> My question(s):
>
> Why did the GMC MH use this method?
>
> Was it the method used on the Toro?
>
> What is the purpose of the tight tolerance between the fan and
> the venturi ring? Noise reduction? Fan efficiency?
>
> Just curious.
> --
> Steve Southworth
> 1974 Glacier TZE064V100150 (for workin on)
> 1975 Transmode TZE365V100394 (parts & spares)
> Palmyra WI
> _______________________________________________
> 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
|
|
|
|
| Re: [GMCnet] Fan Shroud questions [message #163107 is a reply to message #163105] |
Thu, 15 March 2012 20:39 |
James Hupy
Messages: 6806
Registered: May 2010
Karma: -62
|
Senior Member |
|
|
Steve, they made Toronado parts suffice, until they came up with the 77-78
models with the 403. Then they put ducting ahead of the radiator to direct
the air through the core instead of spilling around it. That tight fitting
venturi ring is a PITA when changing fan clutches and/or belts. The 403s
are much easier to change out that stuff. The edges of the fan blades on
the earlier coaches are sure to cut the hell out of your knuckles during
any service up there.
Jim Hupy
Salem, OR
78 GMC Royale 403
On Thu, Mar 15, 2012 at 6:20 PM, Steve Southworth <midlf@centurytel.net>wrote:
>
>
> I'm pulling the radiator and fan shroud off my front clip and am somewhat
> intrigued by the way GMC did this. On my 75 Vette the fiberglass fan
> shroud extends back over the fan, with some clearance between the fan blade
> tips and the shroud, enough to get a fan belt past. On the GMC, as most of
> you are aware, the fan "venturi ring", is mounted to the engine with a very
> tight clearance to the fan blades. This is an expensive method, parts and
> assembly time, compared to some of the alternatives used by GM.
>
> My question(s):
>
> Why did the GMC MH use this method?
>
> Was it the method used on the Toro?
>
> What is the purpose of the tight tolerance between the fan and the venturi
> ring? Noise reduction? Fan efficiency?
>
> Just curious.
> --
> Steve Southworth
> 1974 Glacier TZE064V100150 (for workin on)
> 1975 Transmode TZE365V100394 (parts & spares)
> Palmyra WI
> _______________________________________________
> 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
|
|
|
|
| Re: Fan Shroud questions [message #163114 is a reply to message #163105] |
Thu, 15 March 2012 21:53 |
kingd
Messages: 592
Registered: June 2004
Karma: 2
|
Senior Member |
|
|
This is GMC related but not GMCMH. My 2000 Yukon XL came from the factory with a "split" fan shroud. Upper and lower. I just changed a water pump, fan clutch and thermostat housing. About the only tools needed were a wrench to disconnect the battery, a 15 MM socket and a 10 MM socket. Of course a couple of ratchets and a screw driver. I'm glad it has a serpentine belt with a spring loaded tensioner as no trying to adjust the belt required.
DAVE KING
DAVE KING
lurker, wannabe
Toronto, Ontario, Canada
|
|
|
|
| Re: Fan Shroud questions [message #163115 is a reply to message #163114] |
Thu, 15 March 2012 21:58 |
Bob de Kruyff
Messages: 4260
Registered: January 2004
Location: Chandler, AZ
Karma: 1
|
Senior Member |
|
|
Many of these design issues are driven by the assembly process. Dropping the body on an assembled chassis requires a lot of concessions that may not seem obvious. Most full frame cars of that era had the body drop of the basic firewall back and then the front sheet metal (including the cooling components) was assembled later. The GMC didn't have that luxury.
Bob de Kruyff
78 Eleganza
Chandler, AZ
|
|
|
|
| Re: [GMCnet] Fan Shroud questions [message #163117 is a reply to message #163105] |
Thu, 15 March 2012 23:23 |
Mr ERFisher
Messages: 7117
Registered: August 2005
Karma: 2
|
Senior Member |
|
|
doesn't matter
do this
http://www.gmcws.org/Tech/fan_shroud/fanshroud.htm
or this
http://www.appliedgmc.com/prod.itml/icOid/584
gene
On Thu, Mar 15, 2012 at 6:20 PM, Steve Southworth <midlf@centurytel.net>wrote:
>
>
> I'm pulling the radiator and fan shroud off my front clip and am somewhat
> intrigued by the way GMC did this. On my 75 Vette the fiberglass fan
> shroud extends back over the fan, with some clearance between the fan blade
> tips and the shroud, enough to get a fan belt past. On the GMC, as most of
> you are aware, the fan "venturi ring", is mounted to the engine with a very
> tight clearance to the fan blades. This is an expensive method, parts and
> assembly time, compared to some of the alternatives used by GM.
>
> My question(s):
>
> Why did the GMC MH use this method?
>
> Was it the method used on the Toro?
>
> What is the purpose of the tight tolerance between the fan and the venturi
> ring? Noise reduction? Fan efficiency?
>
> Just curious.
> --
> Steve Southworth
> 1974 Glacier TZE064V100150 (for workin on)
> 1975 Transmode TZE365V100394 (parts & spares)
> Palmyra WI
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
>
--
Gene Fisher -- 74-23,77PB/ore/ca
“Give a man a fish; you have fed him for today --- give him a URL and
-------
http://gmcmotorhome.info/
Alternator Protection Cable
http://gmcmotorhome.info/APC.html
_______________________________________________
GMCnet mailing list
Unsubscribe or Change List Options:
http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
|
|
|
|
|
|
| Re: [GMCnet] Fan Shroud questions [message #163222 is a reply to message #163117] |
Fri, 16 March 2012 20:53 |
midlf
Messages: 2212
Registered: July 2007
Location: SE Wisc. (Palmyra)
Karma: 1
|
Senior Member |
|
|
Yep Gene I am going to do the DIY or one of the purchased solutions. I'm leaning toward the DIY because of the ability to easily drop the bottom half for service work.
Thanks for the WS link. It will save me looking for it again.
Steve Southworth
1974 Glacier TZE064V100150 (for workin on)
1975 Transmode TZE365V100394 (parts & spares)
Palmyra WI
|
|
|
|
|
|
GMCforum
Search
Help
Register
Login
Home
