Crankshaft Timing Sprocket

[TonyJetta]

Well, I think my B4 is another victim of the "D" shaped timing sprocket failure.

As some of you may have been following, I borrowed a set of PP520 injectors (and nozzles) from Abacus, to use while mine were sent out for balancing and install of Titan 502 nozzles.

It seemed no matter where I set the IQ, it would smoke. More so with lower IQ. But over the course of 500 miles, I would notice more smoke at times versus other times.

Monday, 6/17, I attempted to start the car for my commute into work. It seemed to be cranking fine, but wouldn't fire. I cycled the key and reattempted to start the engine. This time it fired and started. But not without a few puffs of gray smoke. I thought this was odd, considering the car was outside, and it was 70F at 5AM! Keep in mind I live in the AZ desert, where, for example, this weekend is forecasted to hit 111-112F!

At any rate, I quickly shut off the engine and have not restarted it.

I suspect, and a few others agree with me, that the crank pulley is moving and needs to be replaced.

So...parts I have on order:
Crank Yank - mostly because I don't want to fab my own tool - not the forecast above!
Timing belt kit - I have about 20k miles left on this one, so I figured if I do it while it's all apart, I should be fine for the next 60k!
Front seal & front cover gasket - I figure if I'm in there, I'll do it once, do it right, and be done!

If I think about it, I'll post a pic of the original timing pulley and crank snout for reference.

On a related note, I have been running the gates one-way clutch alternator pulley. I still think this is the way to go...I think the majority of damage was done over the 195K without the one-way pulley. Then, the extra power of the chip and then the nozzles.

Tony

 

[Abacus]

Boy, I dunno Tony, mine isn't exactly stock and I don't drive it easy either. I'm still running the original crank sprocket and the solid alternator pulley.

 

[RIP TDI]

What's the history of the crank bolt & sprocket? If it was properly installed and showed no signs of previous movement on the sprocket or crank snout at the time of installation, it should be good.

I did a TB replacement after 9 years (!!), and had a new sprocket and crank bolt on hand, assuming that the bolt I installed 9 years ago on the original sprocket would have allowed some sprocket movement by now. But it was immaculate. The bolt broke free in a smooth progressive manner, unlike the sudden "crack" that some report during removal. Its as if I could almost feel the bolt "de-stretching" (at least partly so). I had originally installed it with oiled threads and head flange and, of course, torqued it correctly.

I believe incorrect bolt installation or the failure to correct the effects of previous movement on the snout is the cause of most subsequent sprocket movement and that oiling the threads and head flange is more important than some believe.

BTW - solid alternator pulley for all 9 years.

 

[TonyJetta]

Thanks fellas.

As far as I know, the pulley and bolt are original. But, there are times when I think the car actually has closer to 400k miles, as opposed to the 233k on the odometer.

I'll know more when I get it apart this weekend.

Tony
Sent from my e-diesel fleet

 

[914fan]

I pinned mine a while ago. I just had the gear off to check how its doing, It has tiny cracks where I pinned it. The metal is thin where the bolt head is, and there are micro cracks on my gear. The good news is nothing moved. Ive ordered another gear and will be pinning it only half way and from the rear of the gear. Ill grind down a couple pins to a point so I can dimple the gear and then drill it perhaps 1/2 inch into the thickest part of the gear. Also I removed the PS bracket and used a file to flatten the crank snout. It was a bit buggered up. The balancer is running much more true now.

Its not a difficult job by any stretch of the imagination. The crank and gear are not very hard. The crappy harmonic balancer bolts are harder to drill out than the crank or gear. Be sure to order the hardened ones, and I recommend an extra gear bolt. There one time use, and if you oops, then you have an extra. $5 is cheap insurance.

Note, the gear will crush a tiny bit. Make sure your pins are just below flush if you use through pins. I think that's what caused my cracks. I know the gear crushes cause its a tight fit for the balancer, and it was even more tight after re installing this gear. At least my gear crushed a bit.

Lastly, I was able to tighten the crank bolt by setting the parking break in the driveway, putting it in 5th, and using the engine to hold the crank while I did the last 90 degree turn. I needed an impact to remove the bolt when I took it apart for inspection.

Good luck

 

[Abacus]

Lastly, I was able to tighten the crank bolt by setting the parking break in the driveway, putting it in 5th, and using the engine to hold the crank while I did the last 90 degree turn. I needed an impact to remove the bolt when I took it apart for inspection.

Really? I have never heard of anyone doing it that way, but that's good if it's possible. I'm surprised it worked since I would think you'd damage other drivetrain parts as a result, if it would even hold.

This is the amount of torque it takes:

Homemade tool, using 3/16" steel: just barely heavy enough.

Stock (old) bolts used to hold the tool:

And the cheater bar attached to the breaker bar, for additional leverage. It's two pipes inside one another, so both are bent meaning they won't come apart now:

It takes a bunch of torque to lock the bolt down. The initial 66 ft-lbs is easy, it's the additional 90° that is the bugger.

 

[RIP TDI]

Really? I have never heard of anyone doing it that way, but that's good if it's possible. I'm surprised it worked since I would think you'd damage other drivetrain parts as a result, if it would even hold.

I've read of placing a wedge pin in a flywheel ring gear tooth. It apparently worked without breaking the tooth.

 

[Abacus]

I have done that to tighten the flywheel bolts (44 ft-lbs + 90°), but not tightening things on the other end of the motor. I would question the torsional rigidity of the crank across a span that large, which is one of the reasons holding tools are localized in nature.

But I am certainly no expert here and am just throwing things out there. Personally, I wouldn't do it.

 

[RIP TDI]

I have done that to tighten the flywheel bolts (44 ft-lbs + 90°), but not tightening things on the other end of the motor. I would question the torsional rigidity of the crank across a span that large, which is one of the reasons holding tools are localized in nature.

But I am certainly no expert here and am just throwing things out there. Personally, I wouldn't do it.

I wouldn't do it (or the 5th gear hold) either.

 

[KLXD]

Tony, you messed with the IQ but did you see any change in the timing?

 

[TonyJetta]

I wasn't looking at timing when I was adjusting iq.

Tony
Sent from my e-diesel fleet

 

[914fan]

I should mention that I put the bolt on hand tight, install the old belt and set the timing. the engine does turn over a bit well it takes up the slack in the transmission, but the clutch held. I marked the bolt andd gearaftter the initial 66 torque, with the start and 90 degree stop marks. I used a 2 foot breaker bar and jut kept puling. If the egie turns with the tb on, and licks removed, I'm not worried

 

[914fan]

what am I missing here

 

[greenie]

I did torque to 66, marked the bolt and then finished with an impact gun till the mark moved 90deg. Been driving since

 

[Abacus]

You're brave hammering the crank bolt on with an impact gun. I'd be worried about cracking the crank snout that way.

 

[KLXD]

I wasn't looking at timing when I was adjusting iq.

Tony
Sent from my e-diesel fleet

If you suspect a bad crank/sprocket interface, seems to me you'd want to check if timing changes.

 

[TonyJetta]

As it turns out, I dodged a MAJOR bullet today.

The bolt holding the crank pulley on, was only hand tight. Literally no effort with a breaker bar and the bolt was off!

Subsequently, the pulley was wandering / wobbling. I'll post some pics later.

The crank snout had minimal damage. Nothing that 15 minutes with a flat file couldn't clean up.

Everything came apart and went back together with minimal issue.

At first I thought the flywheel had no timing mark. Until I got the dial indicator out and set #1 to TDC. THere it was!

I forgot what a PITA it is to adjust the timing on the 1Z/AHU's! In particular, bumping the starter to align the access holes to loosen then tighten the IP mounting bolts. I'd swear I went back & forth >20 times. I almost went back under the car to pull the belt cover off.

I also replaced the front seal.

I have the timing set at about 100 degrees. It sounded like injector knock before I adjusted the timing. I know this is above the blue line. I did advance the IP 1 tooth...starting to look like it may be too much.

Tony

 

[greenie]

I did it along time ago. And have had it apart since for other reasons and saw no problems with it. But I do hear ya.