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Serp. Belt Issue

93Rubie

Well-known member
Joined
Jul 19, 2009
Messages
777
Location
PA
Corvette
1993 Ruby Red 40th Anniversary Coupe
I have a minor issue here and I am wondering what you all think. I replaced the serp. belt last year and maybe have about 3500miles total on it. When I drive normally without getting on it the belt stays in place on the pulleys. However, when engaging in WOT throttle activities the belt tends to walk back a rib towards the timing cover on the crank pulley. I can lift the belt off the idler pulley and place it back where it is supposed to be and then start the engine. This always moves the belt back into line on the crank pulley. I just replaced the harmonic balancer as the old one was starting to wobble some, the belt did the same thing with the old one. I figured with the wobble that was causing the issue. The marks on the tensioner are between point B-max belt length and C-belt replacement. Now I have had the belt off maybe a half a dozen times to do various work on the car since I put it on. I am doubting that the belt is the issue. I think I may have a bad tensioner, it does move freely and has resistance to movement with a wrench but that doesn't necessarily mean anything. My best guess is that a high RPM's when the belt is experiencing high amounts of centrifugal forces that the belt slips off a rib because the tensioner cannot hold it onto the pulleys.

I do not want to replace the belt they are 50 some bucks and the tensioner is 17 years old the belt a year old. So I doubt it is the belt but it is possible, weirder things have happened.

Is there any accurate measurement I could do to the belt off the car to determine if the belt is within spec. and possibly rule that out. I didn't look real hard in my FSM for belt length so if anyone knows...

Your thoughts?
 

gmjunkie

Well-known member
Joined
Nov 11, 2004
Messages
4,547
Location
Old Fort NC/Vero Beach FL
Corvette
03 Z-51,78 L82 Coupe
I have a minor issue here and I am wondering what you all think. I replaced the serp. belt last year and maybe have about 3500miles total on it. When I drive normally without getting on it the belt stays in place on the pulleys. However, when engaging in WOT throttle activities the belt tends to walk back a rib towards the timing cover on the crank pulley. I can lift the belt off the idler pulley and place it back where it is supposed to be and then start the engine. This always moves the belt back into line on the crank pulley. I just replaced the harmonic balancer as the old one was starting to wobble some, the belt did the same thing with the old one. I figured with the wobble that was causing the issue. The marks on the tensioner are between point B-max belt length and C-belt replacement. Now I have had the belt off maybe a half a dozen times to do various work on the car since I put it on. I am doubting that the belt is the issue. I think I may have a bad tensioner, it does move freely and has resistance to movement with a wrench but that doesn't necessarily mean anything. My best guess is that a high RPM's when the belt is experiencing high amounts of centrifugal forces that the belt slips off a rib because the tensioner cannot hold it onto the pulleys.

I do not want to replace the belt they are 50 some bucks and the tensioner is 17 years old the belt a year old. So I doubt it is the belt but it is possible, weirder things have happened.

Is there any accurate measurement I could do to the belt off the car to determine if the belt is within spec. and possibly rule that out. I didn't look real hard in my FSM for belt length so if anyone knows...

Your thoughts?
Take the belt off and flip it around back-wards from the position it is now! :thumb

If it stays Put,"Run It"!! :thumb:thumb

If it still Walks Back,"Replace the 2 Idler Pulleys"!!! :thumb:thumb:thumb

If it then Walks Forward,"Replace the Belt"!!!! :thumb:thumb:thumb:thumb

:beer
 

boomdriver

Well-known member
Joined
Dec 18, 2008
Messages
1,888
Location
texas
Corvette
87 z-51
I just did this with mine...3 belts within a month. Ended up being the tensioner. Too soft and the pulley bearing was getting loose. If you can see a tensioner move, or wiggle while running, its bad.
 

Hib Halverson

Technical Writer for Internet & Print Media
Joined
Jan 10, 2001
Messages
13,453
Location
CenCoast CA
Corvette
71 04 12 19
One piece of information is missing and that's the mileage on the engine. Being the engine is in a 17 year-old car, the miles might be reasonably high and if it is, it could be the belt tensioner is faulty. I'd investigate that first.

Unless the belt is not the right part for your application or is a low cost, poor quality unit, 3500 miles on the belt should not cause any problems. If the belt is not a top quality part, I'd replace it with one that is and here are my suggestions starting with the best:
1) Goodyear "Gatorback"
2) GM Parts
3) Gates
4) Dayco

Lastly, although it's unlikely, don't rule-out a pulley alignment problem.
 

93Rubie

Well-known member
Joined
Jul 19, 2009
Messages
777
Location
PA
Corvette
1993 Ruby Red 40th Anniversary Coupe
I actually already tried flipping it around, guess I should have mentioned that. The car and engine have 52500 miles on them, and it is a GM belt. I should also mention it is the double sided ribbed belt.

I'll have to poke around with it, and see if I don't have a pulley alignment issue. I drove it this morning and it was fine but I didn't ever get near WOT.

I think I will try a new tensioner and make sure my idler is in good shape.

I agree with you Hib on Goodyear Gatorbacks being excellent belts, I have one on my DD Ford Focus.
 

Davem

New member
Joined
Dec 7, 2007
Messages
4
Location
Coaregold, ca
Corvette
1986 Black Coupe
I had the same issue, replaced pullys ect. Turned out to be the tensioner.
 

boomdriver

Well-known member
Joined
Dec 18, 2008
Messages
1,888
Location
texas
Corvette
87 z-51
I actually already tried flipping it around, guess I should have mentioned that. The car and engine have 52500 miles on them, and it is a GM belt. I should also mention it is the double sided ribbed belt.

I'll have to poke around with it, and see if I don't have a pulley alignment issue. I drove it this morning and it was fine but I didn't ever get near WOT.

I think I will try a new tensioner and make sure my idler is in good shape.

I agree with you Hib on Goodyear Gatorbacks being excellent belts, I have one on my DD Ford Focus.


you cant see the problem.
The tensioner plastic bushing inside with the spring gets worn out and the tensioner seperates a little. That throw the alignment of the pulley off. There is no repairing it either. I tried oiling the spring area, other lubes, won;t help. its got physical damage that you cant see and this allows the tensioner arm to move around and throw belts. AT $45 a belt,. a $90 tensioner is cheap.
 

boydrm

Member
Joined
Mar 9, 2011
Messages
7
Location
Glen Burnie, MD
Corvette
1999 Black Coupe
I had 2 pulleys replaced and the squealing noise got louder. Next, I had a Goodyear "Gatorback" installed and the noise is gone.
 

93Rubie

Well-known member
Joined
Jul 19, 2009
Messages
777
Location
PA
Corvette
1993 Ruby Red 40th Anniversary Coupe
Even though this is an old thread, I'll follow up with what I did.

The new belt and tensioner held if in place for about a year. Then one day out of nowhere it shredded itself again.

I decided to bite the bullet and do the TSB for converting to a single sided setup. I got the USED smooth power steering pulley with pump for about 85 bucks!!! Two smooth idlers and a one sided belt. When pulling the plastic grooved pulley off, I noticed the end of the pump seemed a little far out of the pulley. I looked in the FSM for specs. the pulley was seated WAY to far in....stupid plastic cap thingy...that hid this. Had to be out of alignment, did not show with a stright edge best I could tell, when I checked. Funny part is that once I got it off, this plastic pulley never moved the rust ring showed me that. Had to be like this from the factory, is my best guess. I left the plastic cap off, for the new steel pulley, FYI.

I put all the new one sided stuff on and 16+ drag strip passes, 4 auto-x's and countless WOT thru the gears runs, it is still in place and just fine. I still have a 100mi double sided belt and two newish grooved idler pullies if anyone wants them. ALso, a good used plastic grooved power steering pulley.
 

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