[s-cars] sheared crankshaft pulley

[djdawson2 at aol.com]

 Scott, I always appreciate some of our differences in opinion... dating back to how to relay euro headlights.? However, I guess there are a few times where I shrug and say "to each his own."

I worked my way through college as an auto mechanic... and in a college town, that meant a ton of water cooled VWs and Audi 4ks.? I couldn't possibly count the number of times I've done timing belts.? I've owned 8 different water cooled VWs, and 9 different Audis of my own.? All of their crank/cam pulley arrangements are essentially the same.? I have yet to replace either a pulley or a bolt.? I guess to me that extends beyond luck... as my experience with these dates back to 1983.

In S cars, I've done quite a few as well... for myself and others.? Never a failure.? My cam pulley has been off and on quite a few times for exhaust cam swaps... still no failures.

Your statement that the bolt doesn't hold the gears in place... I would argue vigourously.? The keyway is for positioning, the bolt provides the clamping force.? What's the torque spec for a crank bolt?? Think it's that high because the load is on the key?? I don't think so.? Tell you what... why don't you try firing up a car with either the cam or the crank bolt tightened to "snug" and see how long the key survives?

Again... each to his own.? However, I've got 26 years worth of data points, and have yet to have one fail.? I think it is very important to avoid the use of impact tools on those items, unless your intent is to remove and discard them.

Maybe I am just lucky... heck, I've got a 240k car whose CPS and 1.8t coils have never failed....

Respectfully, that's my .02

Dave


 


 

-----Original Message-----
From: QSHIPQ at aol.com
To: Djdawson2 at aol.com; cody at 5000tq.com; david.giannandrea at sbcglobal.net; s-car-list at audifans.com
Sent: Wed, 21 Jan 2009 9:27 pm
Subject: Re: [s-cars] sheared crankshaft pulley
















You guys are kidding right?!


Timing Belt with new gear and new bolt only, both are one time use 
IME/O.? The bolt doesn't hold that gear in place, the key does, BTST 
failure.? IME/O it has nothing to do with the install or the removal tools, 
it has to do with heat cycles, stress, and shear.? The bolt is 12bucks and 
is a 1 time stretch bolt, the gear is 40 bucks and it's key is crappy pot steel 
that many times is hard to see the cracks.


?


IME with S cars over the years, I've seen more failed keys than not.? 
The *install* can cause it to fail just as easily, especially if reusing the old 
stretch bolt to factory torque.? I throw away the gears regularly, but kept 
the one crank bolt that stretched itself almost to shear, and managed to get it 
out before it broke all together.


?


I think anyone that's removed and re-installed a used?crank gear is 
just lucky.? The good news is that usually the key cracks below the 
keyline, and it usually stays in place that way until removed.? I see it 
more on the S car than any other, but the problem dates back to the 5000.


?


My .02 arbitraged thru the peso


?


Scott J


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In a message dated 1/21/2009 1:35:49 P.M. Central Daylight Time, 
djdawson2 at aol.com writes:



I 
  agree.? I have never replaced a cam or crank gear, no have I had one fail.? 
  The clamping force should keep the key from ever getting damaged, unless there 
  is work performed with an impact.







-----Original 
  Message-----
From: John Cody Forbes <cody at 5000tq.com>
To: David 
  Giannandrea <david.giannandrea at sbcglobal.net>; 
  s-car-list at audifans.com
Sent: Wed, 21 Jan 2009 10:59 am
Subject: Re: 
  [s-cars] sheared crankshaft 
  pulley










I've had one shear on me 
  while in motion, and have taken apart an engine 
that had damaged it to 
  where it would have sheared soon. In my experiance 
it's not a disassembly 
  problem, it's an assembly problem. If the crank 
pulley is installed with 
  an impact instead of being torqued with the proper 
tools it is highly 
  likely that it didn't get tightened enough and will 
vibrate and slowly 
  wear away the key on the pulley until it finally shears.

The one that 
  sheared on me while driving was a car that I had recently 
purchased and 
  had a t-belt job performed just before I purchased the car. 
Driving down 
  the highway at 70mph I heard a sound that I can only describe 
as the sound 
  you get rattling a piece of silverware in a wine glass and the 
engine lost 
  all power. After costing to the side of the road it was obvoius 
that all 
  compression had been lost. Spinning the engine with the starter I 
could 
  see the flywheel turning, but the crank pulley did not turn. Upon 
closer 
  inspection I could actually see the bolt for the crank pulley turning 
with 
  the crank whle the pulley stayed stationary. That engine lunched all 
ten 
  valves.

-Cody Forbes

David Giannandrea wrote:
> In the 
  thread about t-belt maintenance Robert Myers said he had seen
> two 
  sheared pulleys. From what I've read (and experienced with the
> shop 
  that ruined the oil pump pulling out the crankshaft seal) the
> 
  crankshaft pulley can be ruined if impact tools are used to remove
> the 
  crankshaft bolt.
>
> Additionally, it seems fragile enough to 
  simply fail during a proper
> removal too. When assembled, the pulley is 
  held so tightly with
> 300ftlbs of torqued compression, that I doubt it 
  can move.
>
> Robert. Give up your stories on how it happened. We 
  need to know.
>
> David G.






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