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crankshaft keyway mushrooming


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11 replies to this topic

#1 aa8jzdial

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Posted 13 March 2006 - 09:30 PM

Found a ej22 with less then 100k miles for good price. Haven't paid anything yet.
Took the front output gear off (that drives the timing belt) and noticed some slight mushrooming on the keyway groove. I don't have enough experience to make a call on this but have read on this site about that gear spinging on the crankshaft. I am nervous.
Is any acceptable? If not, I expect the only option is new crank and that will not happen.
Any thoughts?
tnx
rick
w mi

#2 WAWalker

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Posted 14 March 2006 - 12:14 PM

Seems that this problem stems from improper crank bolt torque when timing belt is replaced. Depending on damage done, it is usually fixable.

If key way isn't completly gone and will still hold a key, this is my fix.
Posted Image

Most prefer to throw new parts on, locktite, and over torque the crank bolt. Then hope for the best.

Because the crank pully does not fit all the way onto the crank shaft snout, when it loosens it wobbles and causes wear not only to the inside of the pully but also the crank shaft. There for a new pully is not a tight fit on the worn crank shaft and dosen't nessasarly spin true and can cause everything to loosen up again for a second failure and more damage.
The key way damage is a resault of backlash when the the crank bolt is not holding the timing belt sproket tightly in place.

By connecting the crank pully and timing belt sproket together with dowel pins you keep the crank pully center and spinning true, and basicly have the entire crank shaft snout supporting the crank pully, rather than the very tip.

Here is an example of a failed "locktite & and over torqued crank bolt" fix.
Posted Image

After that "fix" faild the next person who tried to take it apart broke the over torqued crank bolt off in the end of the crank shaft. Which is too bad because I think I could save this one but the broken bolt is going to be a challange. Not the first broken 2.2L crank bolt I have seen but will be my first attempt at removing one.

#3 johnceggleston

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Posted 14 March 2006 - 12:37 PM

my mechanic glued my 93 2.2l back together and i was able to get another 20k miles before i wrecked it. the pins sound like a good idea.

my guy said the cause was from improper torque, i would think locktite would help. but he said the manual calls for "clamping flywheel tight" so it won't rotate, before torquing the crank bolt. most back yard mechanics don't take this step and therefore are just asking for trouble long term. apparently you can't torque it correctly if the crank rotates,

on my next car, 95 legacy 2.2l, i noticed the "off center wobble" of the crank bolt before it fully failed. by setting the pulley correctly, with locktite, and letting it set over night before troquing the bolt, you decrease the likleyhood of it moving wile torquing. i'm still running the 95 and just changed the timing belt again @ 160k (bought it at 75k).

john

#4 Olnick

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Posted 14 March 2006 - 12:38 PM

Nice piece of engineering, WA!

#5 WAWalker

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Posted 14 March 2006 - 01:04 PM

Dosen't take much to hold the crank pully for proper torque. A $35 tool.
Posted Image

I torque the crank bolt to 110 ftlb. which is well over spec, but seems to be the accepted practice.

#6 WAWalker

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Posted 14 March 2006 - 01:19 PM

Nice piece of engineering, WA!


Wasn't my idea. A friend in Seattle told me about it. I asked him why he hasn't made up a bunch of kits and marketed them. He said most people want to go the cheap and easy route. He is right. But when I charge a customer for a repair I want it to last, so I built me a jig and this is the method I use.

#7 cookie

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Posted 14 March 2006 - 01:30 PM

Looks nice! on my last Mercedes I made a custom key when faced with this problem. Your version is tough enough for a Mack truck.

#8 grossgary

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Posted 14 March 2006 - 01:52 PM

i like the sound of that fix too.
i would avoid locktite myself.

#9 aa8jzdial

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Posted 14 March 2006 - 07:41 PM

Thank you WAWalker for a very informative post. I have access to a darned good 72 year old cigar smoking machinist who loves challenges. This may be just the ticket.

Having said that though I still have some concern.
With your elegant fix, the woodruff key will not be called on to take near the torque as the original design. This is good thing as my enlarged keyway has a noticable amont of slop. The pinching of the crank pulley between the bolt and the crank should carry a large amount of the torque via the dowel pins and minimize the slop that the timing belt pulley would otherwise experience.
Do you agree?
Do you see a call for any Locktight anywhere?
One more thing. Could I send you a short 2-3 second movie clip showing the slop in the keyway? I hate to go through all the work and find it is too
worn to bother with. If so, drop a note to aa8jzdial@yahoo.com and I will blast off a little mpg file. Assuming the kid will help me figure out how to do it.
Either way, thanks agn.
rick
w mi

#10 WAWalker

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Posted 15 March 2006 - 10:55 AM

You have mail:)

#11 aa8jzdial

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Posted 15 March 2006 - 09:10 PM

WAWalker
You too have mail. I think the video will show wear to the point of needing to return this motor and search for another.
This website is a great service.
Thanks to all.
rick

#12 operose

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Posted 16 March 2006 - 03:10 PM

"Most prefer to throw new parts on, locktite, and over torque the crank bolt. Then hope for the best."

I did this, but without the new parts.. now I think my waterpump failed, and I have to take it all apart... hope the bolt doesn't break off in the crank tonight when I go to take it off




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