3.4L DOHC Timing Belt walking off

All,

Have a 95 Olds Cutlass Supreme, 3.4L DOHC. Timing belt is walking off
the cam gears, grinding against the cover and shrinking in size.

Questions :

1. What makes this happen ? Idlers & tensioner replacement needed ?
2. Can i mark the CAM gears and crank, remove the 2 idlers, 1 tensioner
and then replace the belt ?
3. What kind of belt is good ?
4. Mechanic wants to charge 1000 to replace..is that a decent price ?

Any other helpful comments/suggestions ?

thanks,

If the belt keeps walking off... you should take a serious looks at
alignment of all pulleys involved. Sounds like their surfaces might not
be parallel to each other for some reason, due to an impact, worn
bearing, etc...

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I don't know your setup, but on lots of engines that means the harmonic
balancer on the end of the crank has failed. It has a rubber ring that
can allow the bottom pulley to become out of line when it fails.

Mike
86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
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wrote:
>
> All,
>
> Have a 95 Olds Cutlass Supreme, 3.4L DOHC. Timing belt is walking off
> the cam gears, grinding against the cover and shrinking in size.
>
> Questions :
>
> 1. What makes this happen ? Idlers & tensioner replacement needed ?
> 2. Can i mark the CAM gears and crank, remove the 2 idlers, 1 tensioner
> and then replace the belt ?
> 3. What kind of belt is good ?
> 4. Mechanic wants to charge 1000 to replace..is that a decent price ?
>
> Any other helpful comments/suggestions ?
>
> thanks,

wrote:

> Have a 95 Olds Cutlass Supreme, 3.4L DOHC. Timing belt is walking off
> the cam gears, grinding against the cover and shrinking in size.

> 1. What makes this happen ? Idlers & tensioner replacement needed ?

It was very common for the plastic idler pulley bearings to wear out
on this engine. To do the job properly, you need to replace the belt,
and the two idler pulleys. Once the tensioner pulley has been removed,
obviously it needs to be inspected, but they rarely gave the same
trouble as the plastic idlers.

> 2. Can i mark the CAM gears and crank, remove the 2 idlers, 1
> tensioner and then replace the belt ?

Yes, if the belt hasn't jumped a tooth, you can do this. If you are
not sure where the belt is, there is a fairly complex way of setting
up the belt and cam sprockets on this engine that involves removing
the upper plenum and both valve covers. A special tool is needed,
and the procedure must be followed carefully.

> 3. What kind of belt is good ?

I would go with the factory original.

> 4. Mechanic wants to charge 1000 to replace..is that a decent price ?

Depending on the labour rate, it may be decent, or it may be outrageous.
To time one of these properly, it's around the 7 hr mark for labour.

Ian