[s-cars] sheared crankshaft pulley

[QSHIPQ at aol.com]

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
 
 
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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