didn't know the timing belt could jump teeth at start up

[jdmawd]

I get everything bolted in and ready to go. I crank the car and it starts but sounds like a diesel motor with horrible lifter tick. so im like WTF? While the car is idling I log my ST fuel trims and get them to 99-101% perfect then the car dies. I try to start it again and I hear a loud snap type of sound as im cranking the car and it will not start. Then I spin the crank with my socket wrench to align the timing marks on the cam gears and dowel pins and they will not line up. the intake cam is off about 2-3 teeth.

That's just wonderful I would have never guessed the timing belt could jump right at start up. The timing belt is very loose also I could almost slide the belt off the gears with my hand. what really sucks is i did the timing best and tensioner last year when i put the new motor in.

 

[CBgst]

I've seen that happen on someone elses car and I couldn't figure out how the hell the timing belt jumped 3 teeth when he started it. He started it up and it backfired and wouldn't start again so he checked the timing and sure enough it was off a few teeth

 

[jdmawd]

Originally posted by CBgst
I've seen that happen on someone elses car and I couldn't figure out how the hell the timing belt jumped 3 teeth when he started it. He started it up and it backfired and wouldn't start again so he checked the timing and sure enough it was off a few teeth

Yup mine started but sounded like a diesel motor with horrible lifter tick. It idled smooth and steady at 750 rpms then it just died all of a sudden I tried to crank it again and I heard a loud snap type sound. it never started again after that.

 

[marshall]

I had that happen to me, it started and the idle shot way up and the engine sounded awful. The sad part is it took me 2 weeks to think to check cam timing...

 

[jdmawd]

Originally posted by marshall
I had that happen to me, it started and the idle shot way up and the engine sounded awful. The sad part is it took me 2 weeks to think to check cam timing...

yeah mine did that but i assumed it was becasue the motor was cold it later came down then died.

 

[autronicDSM]

You probably forgot to tighten the tensioner pulley or your tensioner got stuck. It happend to me once but I caught when I was backing the tool out and I've noticed that tensioner wasn't uncompresing.

 

[jdmawd]

Originally posted by autronicDSM
You probably forgot to tighten the tensioner pulley or your tensioner got stuck. It happend to me once but I caught when I was backing the tool out and I've noticed that tensioner wasn't uncompresing.

I guess that's possible, the t-belt and tensioner was done a year ago but I always had bad idle and a horrible vac signal. I attributed the low vac signal to bad throttle shaft seals and the idle to a bad isc motor. I guess ill try a timing belt job this weekend it will give me an excuse to install my cams and cam gears

 

[91AWDTurbo]

I did my belt a week ago, and got the exhaust cam retarded one tooth. idled very high, but ran fine, revved really quick, and boost came up quick too. never ran it though, checked the marks before i drove it and noticed it was off. also, my tensioner arm did get stuck, so i had to adjust the idle pulley more to bring the arm back down.
JJ

 

[jdmawd]

i found out the problem the oil supply was blocked to the number 13 and 14 cam galleys. this created excessive drag on the intake cam and this caused the belt to skip timing. it also destroyed the cam shaft the cam galley's and the cam caps in those to locations.

 

[thumper]

hey i've got a question. How loose should the timing belt be? There's no set deflection in any books because it's auto tensioner, but i'm curious if mine's alright. I had the cover off for other reasons this weekend, and i pulled on it just out of curiosity. I bet i got 3/4" deflection easily. (i pulled on it in between the 2 cam gears) Also the gears both turned about a tooth i would say, when i pulled on the belt. I hope this is alright i would hate for the timing belt to jump well, thanks for any help

 

[set3422]

when doing tb job, release the retaining pin on the auto tensioner and leave it for an hour or so (i overkilled it by leaving for a day). This method would expand the spring tension and fluid viscosity to its natural state. Compress the tensioner bracket with the special tool till it snags on with a .152" drill bit. On most cases, timing belt jump is due to setting the tension too loose on the tb.

 

[autronicDSM]

Compress the tensioner bracket with the special tool till it snags on with a .152" drill bit.

You mean when 2 holes on the tensioner align? I've always done the following way on my car and never had any problems. Compress tensioner to take belt off. Leave special tool in so those holes align. I install pulley so those 2 small holes are vertical. Put the belt on. Take the special tool out and tension is just fine. There's very little deflection but enough so belt doesn't snap.

 

[set3422]

This method assumes you have a new tensioner. You would pull the pin out before putting on the block or pull it out before compressing the bracket. So this way the tensioner rod would extend all the way.

Not here to correct anyone, but what you did can cause improper tension on the belt and eventually tb will snap or fall off. When those two holes aligned, it doesn't mean you have adjusted the tension right. Those two holes are for taking out the tensioner, so that it wouldn't eject when you take out the two 12mm bolt.

To correctly adjust the tb tension, get a 1/4" drive torque wrench from miller special tools ($$$$) or you could do that mentioned trick above with any drill bit from .15" to .18" diameter(from vfaq).

Basically you would keep on

1) compressing the tensioner bracket till it wedges the drill bit with the tensioner rim/edge (sorry can't find a better word).
2) Pry up the tensioner pulley and tighten it (might have to repeat this step couple times till the gap between the bracket and tensioner is right).
3) Release the special tool and the tensioner rod shouldn't extend further out.
4) If it does, tighten up the special tool with the drill bit on again.
5) Repeat 2) and 3)
6) If the rod stays put, spin the crank six times and see if you can slide the gap with .152" and 0.18" drill bits.
7) You should be able to slide through with .152" but 0.18" should NOT


Good luck.




Set,

Originally posted by autronicDSM


You mean when 2 holes on the tensioner align? I've always done the following way on my car and never had any problems. Compress tensioner to take belt off. Leave special tool in so those holes align. I install pulley so those 2 small holes are vertical. Put the belt on. Take the special tool out and tension is just fine. There's very little deflection but enough so belt doesn't snap.