Caught Cracked Cam gear in time (whew)

[That Guy]

Holly Crap! Those pictures are scary. That was a lucky catch.

Just out of curiosity, how much torque should have been used?

[jimbote]

it's possible the previous installer torqued the cam sprocket well beyond what's required to hold it to the taper...necessitating excessive force to remove it....when torqued correctly it take surprisingly little force to knock the sprocket loose...just a tap

[Franko6]

People who think the use of a punch and hammer damage the sprocket would never have been happy with the 1.6. That was the way it always was done. Also, if you strike the hub of the sprocket, you aren't going to do any damage. We use the sprocket puller tool just for convenience, but have no problem with the sprocket being removed 'the old fashion way'.

Driving the sprocket bolt with an impact is simply STUPID. He's out of his blinking mind...

Changing out worn cam followers is a problem. We recently had an issue that reinforced this concern for us.

A customer had a disastrous timing belt failure. The cam itself appeared undamaged, but there were some lifters that were showing 'bow tie' wear. The old lifters were replaced with new ones. He then drove 2000 miles to my place. Three of the brand new lifters were showing the same wear as before... in that few miles.

Conclusion: The cam wears the lifters as much as the lifters wear the cam. Any cam specialist will make the same recommendation: Replace cam and lifters as a unit, as they wear out as a unit.

In this event, I would keep an eye on the lifters. In another 5-10km, I'd be looking at the lifters again. If the wear repeats, consider cam and lifters being replaced.

[mrvermin]

Originally Posted by Franko6

People who think the use of a punch and hammer damage the sprocket would never have been happy with the 1.6. That was the way it always was done. Also, if you strike the hub of the sprocket, you aren't going to do any damage. We use the sprocket puller tool just for convenience, but have no problem with the sprocket being removed 'the old fashion way'.

Driving the sprocket bolt with an impact is simply STUPID. He's out of his blinking mind...

Changing out worn cam followers is a problem. We recently had an issue that reinforced this concern for us.

A customer had a disastrous timing belt failure. The cam itself appeared undamaged, but there were some lifters that were showing 'bow tie' wear. The old lifters were replaced with new ones. He then drove 2000 miles to my place. Three of the brand new lifters were showing the same wear as before... in that few miles.

Conclusion: The cam wears the lifters as much as the lifters wear the cam. Any cam specialist will make the same recommendation: Replace cam and lifters as a unit, as they wear out as a unit.

In this event, I would keep an eye on the lifters. In another 5-10km, I'd be looking at the lifters again. If the wear repeats, consider cam and lifters being replaced.

I have not checked the lifters for abnormal wear, and will do so tonight, I was told by the mechanic that the Cam looked like there was no wear on it, however, I will be checking again.

Frank, if you are at the next TDIFest, maybe we can look at the Cam wear and go over a few things.

MrVermin

[DogParkGuy]

Originally Posted by mrvermin

PM'ed

MrVermin

I got your PM. You should at least identify whether this was done by a "stealership" or one of the "trusted mechanics".

[Franko6]

DPG,

Seriously, that kind of question has been asked of me. I found no good reason to answer. I don't think we do any service to the one who botched the job by mentioning his name, nor do we truly do the Club any great service. I'm glad that there were no ill effects, other than a cracked cam sprocket to deal with.

I think witch-hunting is crude. I would rather think that the advantage of this thread is a teaching aide that would help avoid a repeat of the same situation, rather than a forum to publicly flog a bad mistake.

Who among you will cast the first stone?

I will revise my comment of 'stupid' to 'ignorant'. Stupid means unable to learn. Ignorant is not aware. I think it is better to treat the problem as ignorance that can be corrected.

[DogParkGuy]

Originally Posted by Franko6

DPG,

Seriously, that kind of question has been asked of me. I found no good reason to answer. I don't think we do any service to the one who botched the job by mentioning his name, nor do we truly do the Club any great service. I'm glad that there were no ill effects, other than a cracked cam sprocket to deal with.

I think witch-hunting is crude. I would rather think that the advantage of this thread is a teaching aide that would help avoid a repeat of the same situation, rather than a forum to publicly flog a bad mistake.

Who among you will cast the first stone?

I will revise my comment of 'stupid' to 'ignorant'. Stupid means unable to learn. Ignorant is not aware. I think it is better to treat the problem as ignorance that can be corrected.

If a dealer had done this, the posting would be headed (in all caps) "Dealer destroyed my engine" or something similar. And the name, address and phone number of the dealer would be included.

I agree with you that everyone makes mistakes and that all cars are complex pieces of equipment.

[BlindViper]

I dont see how using a impact to tighten the bolt would cause that damage.

[Fix_Until_Broke]

I agree - I can't see how overtorquing the bolt would do that kind of damage. Either the bolt would strip, twist off or fracture the tapered hub of the gear axially.

I'd suspect that the gear was pulled by an external puller on the outer perimeter of the gear and caused the cracks which fatigued over time.

[FredS]

Nothing is complicated if you follow the proper procedure, and know your limitations. These engines are like any engine. You need to learn their specifics, in order to do proper work on them, like any other engine.

By the looks of the gear, its almost like they tried to pry it off before loosening the bolt. The one part on the gear is cracked pretty good, then the way the ears attach to the center hub almost look like either a puller or they pried really hard on it. Like mentioned they pop off rather easy, as there isn't that much torque on the taper when the bolt is properly tightened. But the fact the taper isn't cracked seems even over torquing wouldn't cause that damage.

[oldpoopie]

Originally Posted by FredS

Nothing is complicated if you follow the proper procedure, and know your limitations. These engines are like any engine. You need to learn their specifics, in order to do proper work on them, like any other engine.

By the looks of the gear, its almost like they tried to pry it off before loosening the bolt. The one part on the gear is cracked pretty good, then the way the ears attach to the center hub almost look like either a puller or they pried really hard on it. Like mentioned they pop off rather easy, as there isn't that much torque on the taper when the bolt is properly tightened. But the fact the taper isn't cracked seems even over torquing wouldn't cause that damage.

Is is my impression as well. Also, as another poster said, the cracks look fresh. Is it possible that the current mechanic caused the damage and is blaming it on the prior one? Not trying to cause a stir, but it seems plausable. I just cant see that cam gear holding together enought to run in that state.

[KLXD]

Originally Posted by BlindViper

I dont see how using a impact to tighten the bolt would cause that damage.

It wouldn't directly but if it's too tight it might cause the next guy to damage it trying to remove it.

[Ol'Rattler]

Originally Posted by BlindViper

I dont see how using a impact to tighten the bolt would cause that damage.

A 1/2 drive impact at the full setting is capable of torquing to 450 ft. lbs. If you turn it down, you will not have a good idea of how much torque you end up with. Extremely boneheaded of the first mechanic.

The OP might take the shattered sprocket to the first mechanic and have a little talk. If he just didn't know any better, he may want to know how he FUBARed and instead should have used a holding tool and a torque wrench.

[scdevon]

Overtorque didn't damage that gear. It was abused in some other way.

Lucky catch.

[gaddman]

Originally Posted by gaddman

I wonder if the cam pulley has been removed previously with a hammer from the back side rather than a proper puller?

I should have stated it clearer than that. There is the proper way to use a hammer and punch to remove it from the back side.