What exactly is the 1.9 crank pulley problem and best fix..

[myke_w]

I am trying to document the whole story on the 1.9 crank issue for a friend.
Symptoms, pics, exact parts involved, consequences and suggested best fixes would be fantastic...     Maybe we could make a howto out of it?

[935racer]

Use the search there are a few threads ont his already. But to sum it up, the stock crank sprocket and nose of the crankget messed up and your timingbelt will slip and destroy your motor.

[Kudagra]

Use the search there are a few threads ont his already. But to sum it up, the stock crank sprocket and nose of the crankget messed up and your timingbelt will slip and destroy your motor.

does this happen on the 1.6s? I noticed one side of the psudo-keyway on the crank sprocket was worn down on one of my 1.6 engines.

[935racer]

Not really, the later 1.6's and 1.9td's use the same crank sprocket, I think what screws stuff up on the 1.9's is the stupid tensioner and serpentine setup. I havent seen a 1.6 have a crank failure yet. Have you ever seent he crank sprocket and crank nose on the early 1,6's and 1,5's!?! its just a litte removeable keyway.

[wyldman]

I think it's a combination of the serpentine belt,which adds a lot of load to the crank snout,and the harmonic balancer,as it's quite heavy.

Before the TDI crank gear fix appeared,we used to use a lot of special loctite to keep the gear on tight,and use a new bolt which is properly torqued.I have never had one fail that I had put back together.

While it isn't common on the 1.6's,it does happen,but usually due to someone not knowing what they are doing,and not tightening the crank bolt properly (just hand tight or snug).It's usually the DIY's that tend to think you need remove the crank bolt to get the pulley off.They don't tend to let go like the 1.9's though,and jump time.I've seen a lot of them just barely hanging on,yet they never jumped time.

[maddog007]

What are the symtoms of a loose pulley, If you havent been able to get access to it yet,to physicly look at it.
Is there any noises to listen out for, ( mine engine make a slight wirring noise when cold ,it comes & goes every few seconds )
or is there a wobbling of the belt or something ?

[fatmobile]

I got a free '85 Jetta turbo diesel because of a crank bolt problem.
 It happened about 10,000 miles after he had the timing belt changed.
 The second 1.6 TD engine I got my hands on had a new topline head on it and a crank bolt that wouldn't come off without breaking the impact socket ... after we welded the impact socket to the crank bolt it came off real easy (due to all that heat).
 They put that bolt on real good. When we got it off, it was obvious the keyway in the nose of the crank was messed up.
 Long story short I got it running but compression was low so I pulled the engine apart and the pistons didn't have any valve marks in them .... but they were also used (the rings were slopping around in the grooves) NA diesel pistons (looked close and the squirter jets slots were ground into them).
 New head, lame pistons, something happened to it.
 It could have been a broken belt that caused the crank keyway to look bad ... or it could have been a crank bolt incident that caused the "rebuild".
 Every once in awhile I hear of another 1.6TD for sale because of the crank bolt messing up.

[myke_w]

Before the TDI crank gear fix appeared

What exactly is this fix? what's required?

What are the symtoms of a loose pulley, If you havent been able to get access to it yet,to physicly look at it.
Is there any noises to listen out for, ( mine engine make a slight wirring noise when cold ,it comes & goes every few seconds )
or is there a wobbling of the belt or something ?

Exactly, some description of the symtoms would be great.

I think it's a combination of the serpentine belt,which adds a lot of load to the crank snout,and the harmonic balancer,as it's quite heavy.

This all sounds a lot like a problem my old vw tech buddy told me about, except it used to happen on early dashers alot (gas and diesel), vw even had a recall. He speculated that a lot of the problem was people just not getting the crank bolt tight enough, he said he has had to use a 3/4 in impact to get it ungodly tight. Once the big heavy boat anchor of a pulley loosened the bolt, it would wobble around til it shredded the end of the crank and kaput...


Just to be clear,  I am not trying to fix a "problem 1.9" I just want to understand the problem... I am glad to see some answers. Could someone link in known threads that already discuss this? Pics of the damage caused or parts affected, and fixes would be excellent.. pics anyone?  I'll even host em if you email em to me.
[email protected]

[wyldman]

The TDI fix involves welding up the broken keyway\snout,and turning\facing the crank until it's back to original size (minus the keyway).You can then machine a flat on the end of the crank,instead of a keyway,so it will accept the newer TDI crank gear.

With the TDI crank gear,it's a very tight fit,and the gear rides on a machined flat.Even if the bolt cam loose a little,it wouldn't really hurt much.

If have seen a few,where the keyway busted off,and it let go,but the bolt was still tight.It's just a poor design tt place so much load on a little keyway.

You may or may not see the pulley start to wobble.Usually when it starts,you will get a rough idle,or it will be slow to accelerate due to timing fluctuations.By the time you realize it's not running right,it either just goes BANG,and quits,or it will just jump time and run like a dog.Hopefully it doesn't go bang,or you need some expensive engine work.

There is an updated balanced,and a one way clutch type alternator pulley that is supposed to solve the problem,if it hasn't happened yet.

There are suposedly places that do the crank mod in the car,but I usually prefer to pul it apart and have the crank mod done professionally.

[myke_w]

There is an updated balanced,and a one way clutch type alternator pulley that is supposed to solve the problem,if it hasn't happened yet.

Care to elaborate on this? is it the load that the alternator places on the crank pulley that causes the slop to begin?

[wyldman]

No,it's not the alternator load,as it's fairly linear.The problem is the engine does produce continous smooth power.At idle the balancer is being shoved around (hard to accelerate due to it's large mass) when the engine fires,then tries to slow back down between firing strokes.The balancer has a large external weight trying to stop the back and forth movement (torsional vibration),and smooth it out.The weak link is the keyway on the crank gear,so it lets go.

The updated balancer is supposed to have less mass,so less load on the crank snout,as well as softer rubber to absorb more of the shock.

The internal mass of the alternator (not load) has the same effect,as it's trying to keep turning as the engine decelerates between firing strokes.The one way pulley allows the alternator to freewheel forward,and reduce the load applied to the snout of the crank as the engine slows down.

The reason the diesel engine tries to slow down so much between firing strokes is due to the much higher compression.A gasser doesn't tend to have this problem.

The one way alternator clutch also tends to quiet down the serpentine belt tensioner (stops it from slapping back and forth),as it removes the alternator inertia from fighting the crank pulley speed.This slapping tends to wear out the tensioner arm bushings inside the housing,which is an expensive repair.It also makes the idle smoother too.

[A Guy]

Is there a relatively simple way to dertermine if this will fail or has been fixed etc.  I'm looking at a 94 1.9 w/270K and now I'm worrying.  The serpentine belt is pretty shined up and the guy who owns it hasn't done much work to it - definitely not the t belt.  What can I do?  I'm still figuring out my 91 1.6 N/A and now I'm going to learn another one.  any help is greatly appreciated.
Out.
Greg

[wyldman]

There is no way of telling when it could fail.

If the crank bolt has never been touched,it stands a much better chance of surviving.Cars with AC seem to be a little more failure prone,due to the added load on the crank pulley.

The only way to tell if it has been done is to tear it apart and look at it.

[935racer]

No just look at the part # on the sprocket, I'll try and get the #'s on here for refernece. WAy easier than tearing it apart.

[wyldman]

Sorry,I should have been more clear.......You still need to tear it down to check the part number,but you don't need to remove the crank gear itself.You must remove the the belts,pulleys,and balancer to get at the crank gear.

1.9L TDI Crank gear is 028 105 253 D