ALG

I have a 1986 conv. that keeps cutting belts. After installing new belt, I drove it for about 1/2 hour at speeds from 0 to 80 and startys and stopping. Belt not cut. Today I took it out for about 10 minutes and the belt cut after backing out of garage. The belt is cut on the back side closest to motor removing one rib. Looking at the pulleys, from drivers side after the belt is cut, the belt is foward on all pulleys except the a/c pulley which the cut side of the belt is at the rear of the pulley.
I installed a new tensioner but did not help. I cleaned all the ribbed pulley groves.

Any ideas?

383vett

Using washers, shim the ac unit away from the head.

WVZR-1

It would seem that if his problem is at the rear of the pulley - moving it forward would create a more serious alignment problem.

I believe I'd either rent or find someone with a "laser" alignment tool for pulleys and find the real problem. You've demolished it seems now maybe 2 belts for sure?

You mount the laser on a pulley and use it to check alignment of adjacent pulleys. There are different styles - you'd like something like this gates:

http://www.gates.com/brochure.cfm?br...cation_id=2728

ALG

Yes 3 belts each minus 1 rib. I will look to see if i can find a laser to rent.

Thanks

383vett

You're right, I misread the original statement.

gerardvg

Check your pulleys are all lined up straight, check harmonic ballancer pulley is not loose. The tensioner pulley can slip from the bearing so check that ! also check the alternator shaft/pulley has not moved forward or backward but that would show itself with charging problems.

Turning the a/c on and off will put some more tension on the belt and can show it up more.

ALG

Thanks. I used a straight edge and all the pulleys look ok except the A/C which looks like it is back towards engine more than the crank pulley.
New tensioner, and harmonic balancer is not loose. All pulleys are original and check ok.
When i put new belt on everything looks ok and tracks straight.
If i take A/C compressor out and use shorter belt and will it hurt to have water pump running backward? Just a thought.

WVZR-1

I believe a Dorman 34224 eliminator will work for an '86MY L98. It's a pulley and bracket to eliminate the compressor. I believe it's done frequently. Does the AC work and does it have a charge?

leesvet

Go back to the tensioner...

GM changed the tensioner pulley. That will cause this.

The other thing is that these rebuilt tensioners are PP excuses for rebuilds..they are NOT done to spec and the arm often is not pressed onto the spring housing all the way, and the big plastic bushing inside is showing in the edge of the tensioner. This makes the arm out of line. That arm must be pressed on all the way or it tracks wrong and eats a rib off the belt.
If you take a different tensioner and measure the thickness of the mount, one will be slightly thicker due to being assembled wrong/right. This is so critical that its hard to see but it obviosuly matters.

Also, make certain that your new tensioner is resting in place with the alignment notch IN the alignment notch cut-out. If that is not seated right...you can run that long bolt down all day and its going to be out of alignment...

Always return to the last place where some work was performed to find the location of the newest problem. In this case, Tensioner.

...and, I know these chain store rebuilds to be crap and have gone thru 3 before getting one that was good,.

ALG

Thanks. The tensioner seems to have a heavy spring in it. Tomorrow I will take the tensioner off and check if I can see anything and make sure I put it back on correctly.

If it is the tensioner should I be able to see anything while the motor is running? If I rev it up? Will it move from side to side?

Thanks

ALG

WVZR1 No A/C compressor does not come on but pulley turns freely. I do not know if system is charged.

WVZR-1

I only asked because it would seem foolish to use the eliminator to remove the compressor from a "functioning" system for purely diagnostics.

Is your tensioner a "raised edge" version or just a smooth pulley with no "raised edge"? OE would be "raised edge". The locating tab is important.



Reman "tensioner"?

I didn't see the OP mention anything other than "NEW" and I really can't imagine your attempts with remans! Your thought on returning to the "last serviced" part is certainly a good plan.

ALG

Yes it has raised edges. It was called a oem replacement and only difference from old tensioner was a stronger spring. Looked identical.
Thanks

WVZR-1

Compressor pulley is mounted on a fairly large bearing, generally speaking it would be noisy or wobble severely if bad. Maybe yours will tolerate a quick burst of RPM but a more sustained length of time at a higher RPM induces the wobble etc. Pick up an automotive stethoscope and check, You'll find many uses for the stethoscope and they're inexpensive.

Confirm tensioner 1st then I'd go to the compressor. The bearing/pulley is retained by a snap-ring after the clutch plate is removed. I might consider replacing the bearing over spending money on the eliminator. The pulley might actually be bad, it's a welded component. Check closely! Bearing is inexpensive, pulley isn't.

AZ loans all the tools you would need!

leesvet

Yessir...

they sell tensioners that have been reconditioned, new bushing and spring with new pulley.

The place where they screw it up is the fitment of the tensioner arm on the spring housing. That absolutely must be exact, ot the arm position is out of line with the rest of the pulleys on the engine. The locating tab or notch fits the tensioner housing on the bracket where it should be to fall with-in alignment spec, but the arm might be "off" if it was not pressed all the way down on the plastic bushing inside the tensioner housing that holds the spring. The tensioner might act right...no chatter, no movement, no squeel. BUT, the pulley is held out of line and that is what guides the belt to ride on the edge of the tensioner pulley or the next pulley...

To the OP..

a good tensioner does not chatter or bounce around at idle or as rpm increase. It may move gently, slightly as rpm increase but its a smooth precise movement, not jiggling or chattering..bouncing. The tensioner should not make ANY noise, so any squeeking is a sign of a failing bushing inside. Like a belt slipping.

The improper assembly of these rebuilt tensioners can sometimes be obvious when you can see a good size edge of the plastic bushing in the edge of the tensioner housing where the thing was not pressed all the way in. THATS the source of the problem.. I do not remember if it was O'Reallys, or Auto-Moan that had the rebuilts/reman's.

ALG

Thanks. Looking at the tensioner you can see a small seperation and something black. About 1/32" wide. Is that the bushing you are talking about. I put the belt back on with the 5 ribs. I put it foward on the alt., crank pulleys and back on the a/c pulley. It was cut very clean and no ravels.
I took it for a drive of about 45 minutes at all speeds and belt is in same place. With no more damage.

Think it can run on 5 ribs instead of 6 ????

jtownc4

Certainly, if you carry an extra serpentine belt and tools to change it when your custom five rib special fails.... But then you are back to where you started. Lather, rinse repeat