Hi, found this thread:
http://forums.vwvortex.com/zerothread?id=1598023It discusses problems G60s have with crank bolt resulting in damage very similar to what we see with AAZs. In that thread he 'fixes' a damaged keyway by putting in a dowel pin.
Now that Mk3 diesels are becoming more reasonable in price, I am tempted by the occasional newer Jetta or Passat. But the AAZ crank issue gives me cause to pause. Even if I buy one with no noticable wobble, I wouldnt be comfortable driving it without taking some steps to address the problem before it inflicts itself on my wallet. Taking a file to the crank to fit a TDI pulley has been given consideration, but I'd feel quite the fool if I did that and messed it up.
So I submit for your opinion: what would you think of putting in a dowel or two as a preventative measure to shore up a crank pulley/keyway that was otherwise in good shape?
If the crank pulley keyway is solid it will not fail until it becomes slightly loose. Although they may have a frequency for failure, I would bet that if it is tight and you monitor the situation closely that you will have some indication that a problem is coming up. In other words it is good right now SO DON'T MESS WITH IT! That is unless you are planning a trip to Central America and want extreme reliability. Just my thoughts.....
From what I understand, the dowel pin method has mostly been successful at splitting the crank nose, not really a very good solution.
If the crank pulley keyway is solid it will not fail until it becomes slightly loose. Although they may have a frequency for failure, I would bet that if it is tight and you monitor the situation closely that you will have some indication that a problem is coming up. In other words it is good right now SO DON'T MESS WITH IT!
I would mostly agree. If the crank pulley and key are tight there is no need to repair anything, however, I would be inclined to mess with it a bit. Replace the pulley and bolt a soon as possible so you know its properly torqued, then replace the bolt and at least inspect (if not replace) the pulley at each timing belt change. Installing a one way clutched alternator pulley will help and take the bouncing out of the accessory drive and help preserve the crank nose.
I used a pair of pins in mine, along with a generous quantity of JB Weld and the ultra-high temperture loctite (which is kind of hard to find sometimes).
However, I already had a worn crank nose, and at that point had very little to lose by trying it. The JB Weld was to help shore up the worn part of the crank nose.
There was no issue with splitting (you don't need big pins, they're just to prevent movement), the repair was doable under the car, though I did use a drill press for the pilot holes in the new gear.
My father has also used the method in the past (minus the JB Weld), his last repair has been holding for several years now.
I wonder if there's some way to lockwire the bolt in place to prevent it from backing out?
I realized I didn't really answer your question.
My father's experience is the only crank bolts he's seen back out were those that were never installed properly. It's apparently quite common for mechanics doing the belt change to just unzip the bolt with an impact gun, and use one to install the new bolt as well, and not always use a new bolt either.
Any used 1.9 we've bought, we now pull the old bolt out as part of the immediate timing belt change you should do on purchase, and replace it with the new spec one, with loctite and install with the right torque.
None of those have ever failed in service yet.
I wonder if there's some way to lockwire the bolt in place to prevent it from backing out?
I don't think I've actually seen a bolt back out, they usually just break off when the crank sprocket key wears and "cams" outward against the bolt. I've fixed a bunch of these and often had a hellish time getting out the broken bolt stubs that were loctited firmly in place...
I've personally seen 3-4 AAZ crank bolts broken before backing out very much.Some broken ones were even easy to remove(no loctite used).
Some good information here, thanks.
I guess my biggest fear was to buy one I thought was good and then find it is worn already when I take it apart. Knowing that the pinning can be made to work gives me a little more comfort level.
commuter boy: what size pins did you use?