deliriousga

I pulled the covers and tracked the TB around several times. I measured the distance from the front of the cam gears as I turned it about every 6"-12". Every time it measured 3mm from the front and 5mm from the back except for one area. That area is about 4" in length and tracks 1/2mm different (2 1/2mm from the front and 5 1/2mm from the back of the cam gears) from the rest of the belt. I marked the area and rotated it several times and it's the same spot on each rotation of the belt. I checked the tension w/ the Kempf tool and it is still where I set it before driving the first 300 miles on the net TB. All of the gears look great, no wobble, nothing bent and no shine on the teeth yet. Since it's once every rotation on the same spot, it has to be a 1/2mm deflection in the belt itself. Since the deflection is so small, it doesn't look to me to be a problem, just looked much worse from that little hole, but I need other opinions please.

Is this a problem or a normal tolerance in the belt manufacturing? I would like to put the covers back on Wed. night, but not until I know this is ok.

The original post is as follows:

This may be a "thank God I caught it" moment, please let me know.

Since taking her back out on the road (after TB/WP change), I have been checking the TB after each trip to/from work (25 miles). It's been tracking about 1/8" from the front of the cam gears until this morning when I looked at it while the engine was running. On each rotation, it moves in one spot about 1/8" toward the inside and I don't think that's normal (is it?). (Ok, back to positive...saw it before it killed the engine. ) . There is also a squeak sound once each rotation. I'm guessing the squeak is from the belt rubbing something each time around.

I'm taking the covers off this weekend to see it rotate and try and figure out what's happening. If you guys could please let me know anything you've ever found that makes the belt get off track, please list it. I'm going to check everything in that area and don't want to miss anything. Also, I'll put all of the check areas on my website once I get it setup.

Thanks for the help!

heinrich

Hey John Running there constantly is good. But why it's changing during one rotation, not good. Did you replace all the rollers? Did you replace the bushings? Did you check for wear on:

crank timing gear (look carefully)
oil timing gear
cam timing gears (and these could be bent too in unusual circumstances, causing what you describe)

Did you recondition the tensioner? Look at the water pump. Is there rubber residue?

heinrich

Duuude ... I just noticed the name of your town ....

Big Dave

Mine had a bent tensioner pulley bolt. I didn't see it in time. Good luck.


Wait....you already have good luck. You found the problem before the disaster!

deliriousga

Gotta wonder who the heck came up with that name (no pun intended). But hey, I live in the land of the gods as Mr. Pirtle is here too.

When I did the TB/WP here's what else was changed: the two rollers on the idler, idler arm pivot & bushing, rebuilt tensioner, used the Kempf tool to tension, turned the crank about 20 times over the next month while doing other things.

figgen

My wandering timing belt was cause by wear on the crankshaft gear. The gear was tapered high on the engine side and low on the rad side causing the belt to be pushed toward the rad and causing tracking toward the outside of the cam gears. It was most noticeable once the gear was off the car but you may be able to see the wear in place.

H2

The T-belt on my 85S runs constantly and steadily about 1/8" from the edge of the cam gear. I wish it ran more the other direction but it never moves. I've heard that others have had Tbelts that ran very near the edge but never moved for thousands of miles....but I'm a bit **** and not satisfied with that. If I had a belt that was moving back and forth, I'd freak out.

I've ordered the newer style tensioner and will put that on the next belt change...along with a few gears if I notice any wear.

Harvey

PorKen

Did you put in a new shoulder bolt for the tensioner arm?

Jim_H

Are you talking each rotation of the belt or cam gear?

H2

I put in three (3) new shoulder bolts when I was working on my car...and kept breaking them until I got a better torque wrench. That large head can fool you on torque. I think a new shoulder bolt should be a requirement...as well as the plastic gizmos.

Harvey

Jim_H

deliriousga doesn't have the shoulder bolt problem your old buggers do.

deliriousga

Porken - sorry, I called the shoulder bolt a pivot bolt. Yep, changed that too. Jim, so it's not a problem with the 87+?
Each rotation of the belt. The belt is labeled on one spot and I can hear the squeak just after I see the label each time.

I guess this weekend will be timing belt now instead of diagnosing the vibration problem.

Jim_H

I didn't think it was a problem with the newer style tensioner.

Porken - sorry, I called the shoulder bolt a pivot bolt. Yep, changed that too. Jim, so it's not a problem with the 87+?

That would make me think one or two teeth on the belt are bad/weird/funky? If it's only doing one rotation of the belt then I am thinking it's the belt. Since you just finished the TB install you should be getting pretty stronginyour upper body and rotating the engine/ belt past the spot where it moves on the cam gear should be easy I would feel around on the teeth of the belt and see if there are any weird wear area. All this and honestly I don't have a clue what I'm talking about and I am higher than a kite on cold medicine.

FYI, my old belt ran about an 1/8" from the front of the gear and my new one does too. But I get absolutely 0 side to side movement.




Each rotation of the belt. The belt is labeled on one spot and I can hear the squeak just after I see the label each time.

deliriousga

I was wondering if it could be the belt since it tracks straight as an arrow then suddenly moves over the 1/8" for what looks like about a half inch to an inch of length on the belt then it tracks perfectly until that spot again.

BTW, the clutch was a much better workout for the upper body. Especially when you have to take it off again, on again, off again, on again because you keep forgetting things. Once I get her back on the road for more than a week I'm putting the clutch procedure on the web so there's a procedure to follow instead of trying to remember.

Thaddeus

It seems to me like sudden movement to the side would be a very bad thing. Something is pushing the belt over.. putting sideways tension on the belt every rotation. That would seem to be stress on the belt across the width of the belt, whcih could result in a tear by-and-by.

That's an error condition you really need to correct. And when you find and correct root cause, I'd replace that belt since you don't know how many little fibres inside the rubber substrate of the belt have already torn.