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  #1  
Old 03-03-2011, 05:30 PM
clarkerussell clarkerussell is offline
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Putting the camshaft pully back on, is there supposed to be a key?

My camshaft has a notch in it like it should have a key (similar to the crankshaft), as does the pulley. The pully has a key slot as well as a round plug. I don't recall there being a key in the shaft, and the pully does go on tightly with just the round plug filling the camshaft groove.

Subaruparts.com does not show a key for this, but it does show the crankshaft key. This makes me think there is not supposed to be one.

Before I go and do something stupid, can someone tell me if there should or should not be a key on the pulley or the camshaft?

Thanks everyone, I see the finish line now!!!

PS - I have a good number of pictures to help add to the Timing Belt How To. I think a concise document with pictures would help tremendously. This is not a hard task, it's just tedious.

Last edited by clarkerussell; 03-03-2011 at 06:47 PM.
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  #2  
Old 03-03-2011, 06:52 PM
oab_au oab_au is offline
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Re: Putting the camshaft pully back on, is there supposed to be a key?

Quote:
Originally Posted by clarkerussell View Post
My camshaft has a notch in it like it should have a key (similar to the crankshaft), as does the pulley. The pully has a key slot as well as a round plug. I don't recall there being a key in the shaft, and the pully does go on tightly with just the round plug filling the camshaft groove. Subaruparts.com does not show a key for this, but it does show the crankshaft key. This makes me think there is not supposed to be one.

Before I go and do something stupid, can someone tell me if there should or should not be a key on the pulley or the camshaft?

Thanks everyone, I see the finish line now!!!

PS - I have a good number of pictures to help add to the Timing Belt How To. I think a concise document with pictures would help tremendously. This is not a hard task, it's just tedious.
Yes that is the way they are.

A round key in a square hole

Use some locktight on the round plug.

Harvey.
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  #3  
Old 03-03-2011, 09:05 PM
clarkerussell clarkerussell is offline
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Re: Putting the camshaft pully back on, is there supposed to be a key?

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Originally Posted by oab_au View Post
Yes that is the way they are.

A round key in a square hole

Use some locktight on the round plug.

Harvey.
So how would you use locktight on that? I understand using it on the bolt, but why the key hole?
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  #4  
Old 03-03-2011, 09:28 PM
oab_au oab_au is offline
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Re: Putting the camshaft pully back on, is there supposed to be a key?

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Originally Posted by clarkerussell View Post
So how would you use locktight on that? I understand using it on the bolt, but why the key hole?
I use a Lock Tight product for pulley mount, it fills the space around the key and slot, to prevent any backlash that can cause the peg wear.

You can see the type of wear that takes place here.



Harvey.
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  #5  
Old 03-03-2011, 10:04 PM
clarkerussell clarkerussell is offline
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Re: Putting the camshaft pully back on, but I think something is missing.

So does anyone know why there is a key hole on the pulley? Is it to just to confuse us?

Last edited by clarkerussell; 03-04-2011 at 08:34 AM.
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  #6  
Old 03-03-2011, 10:05 PM
Cam Cam is offline
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Re: Putting the camshaft pully back on, is there supposed to be a key?

Quote:
Originally Posted by oab_au View Post
I use a Lock Tight product for pulley mount, it fills the space around the key and slot, to prevent any backlash that can cause the peg wear.

You can see the type of wear that takes place here.



Harvey.
If both the pulley and the cam are in good shape and there is a nice snug fit between the two then I would think that would not happen. Not saying that the thread locker on the keyway is a bad idea, but just that it should not be necessary in a properly toleranced set-up. I would also venture to say that a loose timing belt could add to the chance of that kind of damage occuring.
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  #7  
Old 03-04-2011, 06:19 PM
oab_au oab_au is offline
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Re: Putting the camshaft pully back on, is there supposed to be a key?

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Originally Posted by Cam View Post
If both the pulley and the cam are in good shape and there is a nice snug fit between the two then I would think that would not happen. Not saying that the thread locker on the keyway is a bad idea, but just that it should not be necessary in a properly toleranced set-up. I would also venture to say that a loose timing belt could add to the chance of that kind of damage occuring.
Well Cam, I would venture to say, that when it was assembled at the factory, both the pulley and the cam were in good shape and a nice snug fit, but as you can see it does happen. not only here but at the crank pulley key also.
Using a Lock Tight product on these fits, is very good assurance.

Loose timing belt you have compressed the tensioned, haven't you.

Harvey.
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04 Liberty 30R Auto Premium. 92.000kls.
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  #8  
Old 03-04-2011, 06:32 PM
Cam Cam is offline
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Re: Putting the camshaft pully back on, is there supposed to be a key?

Quote:
Originally Posted by oab_au View Post
Well Cam, I would venture to say, that when it was assembled at the factory, both the pulley and the cam were in good shape and a nice snug fit, but as you can see it does happen. not only here but at the crank pulley key also.
Using a Lock Tight product on these fits, is very good assurance.

Loose timing belt you have compressed the tensioned, haven't you.

Harvey.
I am in complete agreement that it was a snug fit at the factory. And also that the thread sealer is good insurance. The thought behind the loose timing belt is that if it is not tight enough, the "slop" would cause torque to not equally distribute itself among the surfaces the belt touches, and additional torsional stress would occur at the cam pulley that is first in line with the rotation of the belt. If that indeed happened, it would contribute to the deformation of a key like the one pictured.
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  #9  
Old 03-05-2011, 02:45 AM
oab_au oab_au is offline
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Re: Putting the camshaft pully back on, is there supposed to be a key?

Quote:
Originally Posted by Cam View Post
I am in complete agreement that it was a snug fit at the factory. And also that the thread sealer is good insurance. The thought behind the loose timing belt is that if it is not tight enough, the "slop" would cause torque to not equally distribute itself among the surfaces the belt touches, and additional torsional stress would occur at the cam pulley that is first in line with the rotation of the belt. If that indeed happened, it would contribute to the deformation of a key like the one pictured.
No Cam I think you are missing the engineering point. We have a pulley with a square keyway, driving an exhaust camshaft with a square keyway via a round key.
All the load from the pulley to the cam is transfered through the square corners of the pulley and cam keyways edges, bearing against the radial edge of the round key. This small loaded edge of the key, will deform to allow a small amount of backlash, which will increase over time to shear off the key, as has happened.
Filling the space around the round key so that it is fully supported, will prevent it from deforming and develop any back bash.

Personally I would use a square key.

Harvey.
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97 Liberty GX Auto sedan. 320,000Kls.
04 Liberty 30R Auto Premium. 92.000kls.
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