The 1947 - Present Chevrolet & GMC Truck Message Board Network







Register or Log In To remove these advertisements.

Go Back   The 1947 - Present Chevrolet & GMC Truck Message Board Network > 47 - Current classic GM Trucks > The 1988 - 1998 Chevy & GMC Pickups Message Board

Web 67-72chevytrucks.com


Reply
 
Thread Tools Display Modes
Old 12-17-2017, 11:00 AM   #1
J1MMY
Registered User
 
Join Date: Aug 2009
Location: Wiltshire, UK
Posts: 157
How much tension? Drive belt pulley

Hello all

Belt was slipping on my '94 Sierra (4.3, ex USAF beater, no a/c) so ordered in new tensioner and belt. Fitted up and there is really not much tension there at all. Offered the new and old belts up and there is no discernible difference. I have spotted that there is a small aftermarket idler pulley. It is 3" diameter. Is this correct?
__________________
'63 C10 Longbox fleetside
'94 C1500 Sierra ex-USAF beater
J1MMY is offline   Reply With Quote
Old 12-18-2017, 12:04 AM   #2
mountie
Senior Member
 
mountie's Avatar
 
Join Date: Jun 2011
Location: Bradenton, Fla.
Posts: 1,017
Re: How much tension? Drive belt pulley

Would you take a photo of the aftermarket pulley?
__________________
'70 GTO Midnight Blue
'88 GMC Sierra SLE 392,000 miles-(2018) sold to Classic car shop in Germany.
'93 Cadillac STS Black
'93 Mercedes SL 500 Teal
'86 Yamaha FZ750 - 15,000 RPM
'86 Yamaha FJ1200 - Criminally Fast
2016 Ferrari 488 GTB, I drive it - don't own it.
'05 GMC Yukon XL , SLT 4wd ( just purchased 2018)
mountie is offline   Reply With Quote
Old 12-18-2017, 03:12 AM   #3
EVRLET
Junior Member
 
EVRLET's Avatar
 
Join Date: Aug 2015
Location: Las Vegas NV
Posts: 69
Re: How much tension? Drive belt pulley

Even though I don’t own a 4.3, I went through something similar with my 5.7. I own a 1997 Silverado. There are two different alternators. One for a Silverado with all the bells and whistles, and one for other models who don’t need the extra amperage. Because of the two alternators, there are two different belt sizes. The difference in size for the two belts could only be seen when you use an actual belt measurement tool. When I held it up and stretched it in my hands, they looked identical but they were not.
__________________
Customization is what you want it to look like -- not what other people think it should look like
EVRLET is offline   Reply With Quote
Old 12-18-2017, 04:15 AM   #4
J1MMY
Registered User
 
Join Date: Aug 2009
Location: Wiltshire, UK
Posts: 157
Re: How much tension? Drive belt pulley

Idler pulley....



Interesting to note on the belt....part no. on the new one is RK638.
__________________
'63 C10 Longbox fleetside
'94 C1500 Sierra ex-USAF beater
J1MMY is offline   Reply With Quote
Old 12-18-2017, 08:41 AM   #5
mountie
Senior Member
 
mountie's Avatar
 
Join Date: Jun 2011
Location: Bradenton, Fla.
Posts: 1,017
Re: How much tension? Drive belt pulley

I can't see the pic. ( It says to update photobucket account)
__________________
'70 GTO Midnight Blue
'88 GMC Sierra SLE 392,000 miles-(2018) sold to Classic car shop in Germany.
'93 Cadillac STS Black
'93 Mercedes SL 500 Teal
'86 Yamaha FZ750 - 15,000 RPM
'86 Yamaha FJ1200 - Criminally Fast
2016 Ferrari 488 GTB, I drive it - don't own it.
'05 GMC Yukon XL , SLT 4wd ( just purchased 2018)
mountie is offline   Reply With Quote
Old 12-18-2017, 08:44 AM   #6
J1MMY
Registered User
 
Join Date: Aug 2009
Location: Wiltshire, UK
Posts: 157
Re: How much tension? Drive belt pulley

See if this works....
Attached Images
 
__________________
'63 C10 Longbox fleetside
'94 C1500 Sierra ex-USAF beater
J1MMY is offline   Reply With Quote
Old 12-18-2017, 01:33 PM   #7
mountie
Senior Member
 
mountie's Avatar
 
Join Date: Jun 2011
Location: Bradenton, Fla.
Posts: 1,017
Re: How much tension? Drive belt pulley

Opps... I was wondering where it was located on the truck...

The outside diameter / width ? But if it's on the spring loaded tensioner, any dealer will tell you the correct size / part
__________________
'70 GTO Midnight Blue
'88 GMC Sierra SLE 392,000 miles-(2018) sold to Classic car shop in Germany.
'93 Cadillac STS Black
'93 Mercedes SL 500 Teal
'86 Yamaha FZ750 - 15,000 RPM
'86 Yamaha FJ1200 - Criminally Fast
2016 Ferrari 488 GTB, I drive it - don't own it.
'05 GMC Yukon XL , SLT 4wd ( just purchased 2018)
mountie is offline   Reply With Quote
Old 12-18-2017, 01:38 PM   #8
J1MMY
Registered User
 
Join Date: Aug 2009
Location: Wiltshire, UK
Posts: 157
Re: How much tension? Drive belt pulley

Idler pulley sits to the left of the tensioner (when stood at the front of the truck looking in) - presumably where the A/C goes on vehicles that have it.
__________________
'63 C10 Longbox fleetside
'94 C1500 Sierra ex-USAF beater
J1MMY is offline   Reply With Quote
Old 12-18-2017, 01:51 PM   #9
Killer Bee
Registered User
 
Killer Bee's Avatar
 
Join Date: Jan 2016
Location: Barber City, CA
Posts: 1,385
Re: How much tension? Drive belt pulley

agree with above, I would call local dealer with vin, eng, make, model, etc. and they should get to the bottom of it for you.. I would also ditch that unknown aftermarket junk and go back with proper factory a/c or non-a/c serpentine set up..

while a non-a/c engine may have an idler where the compressor would be to keep belt route typical, the idler may not be the same diameter as the compressor pulley so two belt lengths may be available..

good luck!
__________________
I started out with nothing - and I still have most of it
Killer Bee is offline   Reply With Quote
Old 12-18-2017, 02:00 PM   #10
mountie
Senior Member
 
mountie's Avatar
 
Join Date: Jun 2011
Location: Bradenton, Fla.
Posts: 1,017
Re: How much tension? Drive belt pulley

I can't post a photo of a pulley I have. ( I have a frustrating "script blocker" that won't turn off)...

The pully is designed to replace the A/C unit , if removed. Google it.
__________________
'70 GTO Midnight Blue
'88 GMC Sierra SLE 392,000 miles-(2018) sold to Classic car shop in Germany.
'93 Cadillac STS Black
'93 Mercedes SL 500 Teal
'86 Yamaha FZ750 - 15,000 RPM
'86 Yamaha FJ1200 - Criminally Fast
2016 Ferrari 488 GTB, I drive it - don't own it.
'05 GMC Yukon XL , SLT 4wd ( just purchased 2018)
mountie is offline   Reply With Quote
Old 12-18-2017, 02:30 PM   #11
Killer Bee
Registered User
 
Killer Bee's Avatar
 
Join Date: Jan 2016
Location: Barber City, CA
Posts: 1,385
Re: How much tension? Drive belt pulley

Quote:
Originally Posted by mountie View Post
I can't post a photo of a pulley I have. ( I have a frustrating "script blocker" that won't turn off)...

The pully is designed to replace the A/C unit , if removed. Google it.
here ya' go mountie, something like this to run same length belt?

A/C Compressor Bypass Pulley

whole page full popped up with 4.3 chevy search so not sure if this image is accurate but illustrates purpose..

__________________
I started out with nothing - and I still have most of it
Killer Bee is offline   Reply With Quote
Old 12-18-2017, 03:38 PM   #12
mountie
Senior Member
 
mountie's Avatar
 
Join Date: Jun 2011
Location: Bradenton, Fla.
Posts: 1,017
Re: How much tension? Drive belt pulley

That's correct..... it's for when an A/C compressor is removed. It takes it's place if that's what your old belt ran around.
__________________
'70 GTO Midnight Blue
'88 GMC Sierra SLE 392,000 miles-(2018) sold to Classic car shop in Germany.
'93 Cadillac STS Black
'93 Mercedes SL 500 Teal
'86 Yamaha FZ750 - 15,000 RPM
'86 Yamaha FJ1200 - Criminally Fast
2016 Ferrari 488 GTB, I drive it - don't own it.
'05 GMC Yukon XL , SLT 4wd ( just purchased 2018)
mountie is offline   Reply With Quote
Old 12-18-2017, 05:51 PM   #13
J1MMY
Registered User
 
Join Date: Aug 2009
Location: Wiltshire, UK
Posts: 157
Re: How much tension? Drive belt pulley

Interesting pic. I'd also be curious to know the diameters of both alternator pulley types.

Going to a dealer isn't an option as they didn't sell these here on my little island. Tbh I would be surprised if this ever had aircon as most of the ex-forces trucks which surface over here are base models. There is also nothing on the heater panel to suggest it. I take it the bracketry on the front of the engine would be the different for a compressor than that for an idler?
__________________
'63 C10 Longbox fleetside
'94 C1500 Sierra ex-USAF beater
J1MMY is offline   Reply With Quote
Old 12-19-2017, 02:00 PM   #14
Kudzupatch
Registered User
 
Kudzupatch's Avatar
 
Join Date: Apr 2013
Location: GUNTERSVILLE
Posts: 511
Re: How much tension? Drive belt pulley

Why not just buy a little shorter belt?
Kudzupatch is offline   Reply With Quote
Old 12-19-2017, 02:07 PM   #15
mountie
Senior Member
 
mountie's Avatar
 
Join Date: Jun 2011
Location: Bradenton, Fla.
Posts: 1,017
Re: How much tension? Drive belt pulley

Quote:
Originally Posted by Kudzupatch View Post
Why not just buy a little shorter belt?
Not as easy as you would think.... I tried that once. ( Then I got the A/C adapter pulley)
__________________
'70 GTO Midnight Blue
'88 GMC Sierra SLE 392,000 miles-(2018) sold to Classic car shop in Germany.
'93 Cadillac STS Black
'93 Mercedes SL 500 Teal
'86 Yamaha FZ750 - 15,000 RPM
'86 Yamaha FJ1200 - Criminally Fast
2016 Ferrari 488 GTB, I drive it - don't own it.
'05 GMC Yukon XL , SLT 4wd ( just purchased 2018)
mountie is offline   Reply With Quote
Old 12-19-2017, 03:30 PM   #16
Killer Bee
Registered User
 
Killer Bee's Avatar
 
Join Date: Jan 2016
Location: Barber City, CA
Posts: 1,385
Re: How much tension? Drive belt pulley

Quote:
Originally Posted by Kudzupatch View Post
Why not just buy a little shorter belt?
without routing the belt correctly, some of the driven accessories may suffer from lack of belt engagement or friction, and slip..

either a factory delete idler with spec'd shorter belt or a compressor pulley size idler with standard belt would be the best solutions..
__________________
I started out with nothing - and I still have most of it
Killer Bee is offline   Reply With Quote
Old 01-11-2018, 04:21 AM   #17
LT7A
Registered User
 
Join Date: Oct 2015
Location: Seattle, WA
Posts: 702
Re: How much tension? Drive belt pulley

J1MMY, if it doesn't seem like you're getting closer to a solution, maybe you can post pictures of all of the relevant aspects of your setup? Not sure how many 4.3ers there are here because of these being full size trucks but I know there are a few around. CapeCodder has one and is a talented guy. Maybe you can ping him and swap some info. I have a 1999 S15 Jimmy with the 4.3 and could take a look at specifics but I don't know if it's the same setup. Not so easy for you to find one local to look at I'd imagine.
LT7A is offline   Reply With Quote
Old 01-11-2018, 04:56 AM   #18
J1MMY
Registered User
 
Join Date: Aug 2009
Location: Wiltshire, UK
Posts: 157
Re: How much tension? Drive belt pulley

I should have come back and posted earlier - I had a chance to get to a local parts factor and sorted the issue with a 2330mm belt. About 1/4" deflection in the belt (max) and a squeal-free consistent charge. I have no idea if my alternator or idler pulleys are stock but it works. Very happy.
__________________
'63 C10 Longbox fleetside
'94 C1500 Sierra ex-USAF beater
J1MMY is offline   Reply With Quote
Old 01-11-2018, 06:16 AM   #19
Killer Bee
Registered User
 
Killer Bee's Avatar
 
Join Date: Jan 2016
Location: Barber City, CA
Posts: 1,385
Re: How much tension? Drive belt pulley

happy ending
__________________
I started out with nothing - and I still have most of it
Killer Bee is offline   Reply With Quote
Old 01-15-2018, 12:03 AM   #20
diveplane
Registered User
 
Join Date: Nov 2016
Location: Tulsa
Posts: 291
Re: How much tension? Drive belt pulley

Quote:
Originally Posted by J1MMY View Post
Hello all

Belt was slipping on my '94 Sierra (4.3, ex USAF beater, no a/c) so ordered in new tensioner and belt. Fitted up and there is really not much tension there at all. Offered the new and old belts up and there is no discernible difference. I have spotted that there is a small aftermarket idler pulley. It is 3" diameter. Is this correct?
pulley unit is self tension , theres maximum and minimum marks on the pulley tensioner unit.
diveplane is offline   Reply With Quote
Old 01-15-2018, 12:05 AM   #21
diveplane
Registered User
 
Join Date: Nov 2016
Location: Tulsa
Posts: 291
Re: How much tension? Drive belt pulley

Quote:
Originally Posted by mountie View Post
That's correct..... it's for when an A/C compressor is removed. It takes it's place if that's what your old belt ran around.
yes a locked ac compressor can leave u stranded on the road good to have this bypass pulley in the cab.
diveplane is offline   Reply With Quote
Reply

Bookmarks

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT -4. The time now is 12:14 AM.


Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2018, vBulletin Solutions Inc.
Copyright 1997-2013 67-72chevytrucks.com