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Crank Keyway - Is this common?


prelewd

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Tore down my L6 the other week, to replace timing equipment, and found this:

 

ZParts031.jpg

 

Apologies for the bad image quality.

 

The crank keyway looked like it was chipped/chunked out by the key itself, or some other means. I've never seen this before.. Just wondering if you have?

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Had a recent thread about this where someone 'fixed" the problem on their Miata with some red locktite. Do a search. The guy posted detailed articles.

 

I had an old truck that did that, and managed to file out the grooves slightly and fit the next sized up woodruff key.

 

Ghetto fixes, not the correct way to do it, but cheaper than replacing a crank.

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Something similar happened to me (on a friend's audi) after replacing the timing belt & tensioner, we started the car, whent for a ride and everything was ok, the day after, he called me to say that the engin had stopped dead in it's tracks

while accelerating. "The NEW belt could'nt have skipped a tooth could it?"

 

So, I remove everyhting again and WTF!!! On the Audi engin, the key is machined into the crank timing gear and it cracked, the crank spun in the gear, pistons hit the valves and bent all of the intake valves.

 

Lucky for us though, the gear is alluminum so it just got machined off by the crank and it only cost 100$ for a new gear but, it costed 800$ to fix the head.

 

edit: I think it was caused by the fact that his belt was so loose it must have kicked on the gear and slowly cracked the key, people, on Audi world web site, have reported similar events after replacing the t-belt.

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Wow an administrator that helps make the search function easier to use...Maybe you could teach the guys at zcar a thing or two. Or maybe everyone at zcar just needs to come over here.

 

gawd no, please, not that.

Lets keep it informative and fact based here, instead of "the alternative" thankyouverymuch.

 

Improper dampner installation causes it, the other thread covers the repair possibilities. Good Luck!

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no- improper dampner installation does not cause this!

 

how the heck does putting a key in, and sliding a crank pulley on cause it to widen out??

 

im my experiences with keyways being messed up, is that

 

a. pulley comes apart and wobbles on the end of the crank, screwing up the keyway

 

b. timing chain guides arent set right, and the chain "slaps" on the lower gear, causing it to be able to rotate left and right a few mm (keyway messed up)

 

c.bad pulley (euro dampner defect)

 

on a friends car, we just set the key in with JB weld, and JB welded the pulley onto the crank shaft, and put the bolt on with an airimpact....that pulley isnt coming off any time soon :wink:

 

thats why its ALWAYS safe to just get new keys when replacing the timing components...but yeah, take the crank out, weld it up, and cut new keyways into it!

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no- improper dampner installation does not cause this!

 

 

er....yeah. naviathan, here is the perfect example of why not!

 

To be pedantic for those who are so blind as not to see the obvious:

Insufficient torque and lack of proper locking compounds on the crank snout during installation cause the pulley to work during periods of operation, resulting in a wallowed-out keyway. Ergo improper installation caused the malady. Simple Logic. If the bolt worked loose during operation: lack of locking compound and torque at installation, same conclusion. The difference between "root cause analysis" and "anecdotal garbage" is dispassionate apprasial of the actual causes of the failure. To say improper installation does not cause it (and to catagorically insist that in such a manner) is both irresponsible and in clear disregard for the facts of the metter from hundreds, perhaps, collectively thousands of crankshaft snout failures diagnosed by people here on this board. This is not ZCar.Com, people here are much better educated, and far less egocentric than there.

 

In short (and not to overstep my bounds here, this is for the moderators)please take your Z-Car.Com baiting antics elsewhere, as well as grudges, hards-on, and anything else you wish to drag into topics here Bubbles... This site is fact-based and if the facts of a matter disturb you you can argue all you want but it still doesn't change the facts of the matter at hand.

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on a friends car, we just set the key in with JB weld, and JB welded the pulley onto the crank shaft, and put the bolt on with an airimpact....that pulley isnt coming off any time soon

 

That's nice. Hope your friend remembers to tell the new owners about this little "fix."

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er....yeah. naviathan, here is the perfect example of why not!

 

To be pedantic for those who are so blind as not to see the obvious:

Insufficient torque and lack of proper locking compounds on the crank snout during installation cause the pulley to work during periods of operation, resulting in a wallowed-out keyway. Ergo improper installation caused the malady. Simple Logic. If the bolt worked loose during operation: lack of locking compound and torque at installation, same conclusion. The difference between "root cause analysis" and "anecdotal garbage" is dispassionate apprasial of the actual causes of the failure. To say improper installation does not cause it (and to catagorically insist that in such a manner) is both irresponsible and in clear disregard for the facts of the metter from hundreds, perhaps, collectively thousands of crankshaft snout failures diagnosed by people here on this board. This is not ZCar.Com, people here are much better educated, and far less egocentric than there.

 

In short (and not to overstep my bounds here, this is for the moderators)please take your Z-Car.Com baiting antics elsewhere, as well as grudges, hards-on, and anything else you wish to drag into topics here Bubbles... This site is fact-based and if the facts of a matter disturb you you can argue all you want but it still doesn't change the facts of the matter at hand.

I think you're both getting a little too personal, please stop.

 

In my personal experience I had torqued my front crank bolt down with red loctite, the damper came apart and vibrated the bolt loose and it caused this crank problem. I can easily see how not torquing it hard enough would cause the same issue. Doesn't really matter though. We don't need the hostility in the posts here at all, so please leave that crap over at "the other forum".

 

Moving on...

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Since the other post was mine, I should follow up. Beandip suggested I contact Kim Blough at Idaho Zcar, which I did.

 

He said it is fairly common and he has fixed many without any problems. The loctite product to use is Loctite 660 retaining compound. Clean and polish the crank and pulley. put some loctite in the groove and insert the key, then insert the pulley to align and remove the pulley and let set. The 660 is an anaerobic sealer that will be as hard as cement. Further googling 660 on the net found it is also common on miatas, and this compound was designed specifically for this problem.

 

I found it at www.bikeman.com but have not reassembled the engine yet.

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