Slight play in Aux shaft gear?

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Slight play in Aux shaft gear?

Postby Fiat88 on Thu Jun 21, 2012 5:37 pm

I noticed with the timing belt off that the aux shaft gear has what feels like 1/2 in of play when I turn the gear back and forth with my hand. Don't think the shaft is turning just the gear rocking. I did just replace the seal and housing gasket. Anything to worry about or did I screw up something?
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Re: Slight play in Aux shaft gear?

Postby KidDingo on Sun Jun 24, 2012 2:55 pm

Fiat88 wrote:I noticed with the timing belt off that the aux shaft gear has what feels like 1/2 in of play when I turn the gear back and forth with my hand. Don't think the shaft is turning just the gear rocking. I did just replace the seal and housing gasket. Anything to worry about or did I screw up something?



I'm not an expert, but it sounds normal. The aux gear drives the oil pump, so some perceived slack might be expected.
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Re: Slight play in Aux shaft gear?

Postby vandor on Sun Jun 24, 2012 11:47 pm

Fiat88 wrote: Don't think the shaft is turning just the gear rocking.


There should be a dowel pin in the shaft that the gear slides onto that fixes the gear to the shaft. There should be no play at all between the two.
If you have a plastic gear then the center may be starting to break loose...
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Re: Slight play in Aux shaft gear?

Postby Fiat88 on Mon Jun 25, 2012 12:29 am

vandor wrote:
Fiat88 wrote: Don't think the shaft is turning just the gear rocking.


There should be a dowel pin in the shaft that the gear slides onto that fixes the gear to the shaft. There should be no play at all between the two.
If you have a plastic gear then the center may be starting to break loose...

Will check the gear tomorrow and report back.
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Re: Slight play in Aux shaft gear?

Postby Fiat88 on Mon Jun 25, 2012 8:53 pm

Took the gear off and inspected it looked fine structural wise. I did notice that the diameter of the dowel looked much smaller than the hole in the plastic gear. Is it possible the dowel hole on the gear has worn out? Another thing was the aux shaft with the gear removed has a tiny amount of movement. I measured the left and right movement when the gear was on it was about 1/8 of an inch not 1/2 like I thought.
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Re: Slight play in Aux shaft gear?

Postby vandor on Wed Jun 27, 2012 10:16 pm

>Is it possible the dowel hole on the gear has worn out?

Yes, especially if the bolt was snot as tight as needed.

>Another thing was the aux shaft with the gear removed has a tiny amount of movement.
>I measured the left and right movement when the gear was on it was about 1/8 of an inch not 1/2 like I thought.

If it has 1/8" radial play (left and right, or up and down) then it sound like the front auxiliary shaft bushing is very worn.
You should not be able to feel any play, the bearing clearance should be a few thousands.
The front intake camshaft bearing is lubricated through the aux shaft front bearing, so if you have that much play in the bearing than likely that cam bearing is not getting any oil.
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Re: Slight play in Aux shaft gear?

Postby Fiat88 on Wed Jun 27, 2012 10:49 pm

vandor wrote:>Is it possible the dowel hole on the gear has worn out?

Yes, especially if the bolt was snot as tight as needed.

>Another thing was the aux shaft with the gear removed has a tiny amount of movement.
>I measured the left and right movement when the gear was on it was about 1/8 of an inch not 1/2 like I thought.

If it has 1/8" radial play (left and right, or up and down) then it sound like the front auxiliary shaft bushing is very worn.
You should not be able to feel any play, the bearing clearance should be a few thousands.
The front intake camshaft bearing is lubricated through the aux shaft front bearing, so if you have that much play in the bearing than likely that cam bearing is not getting any oil.

Vandor,
Could something be clogged up? I just replaced the head gasket and front seals as I was getting a lot of front oil leaks. The aux shaft seal looked really dried out and old, so suspected that maybe was the main source. Did all front seals and housing gaskets. Could these leaks ruined the bearing?
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Re: Slight play in Aux shaft gear?

Postby manoa matt on Thu Jun 28, 2012 8:39 pm

You are talking about two different situations here.

1. Clearance between the aux shaft and the bearing is measured in thousands of an inch. The aux shaft does not see much load like the crank and cam shafts so its rare the bearings need replaced. To measure the bearing cleanance accuratly you would need a micrometer to measure the aux shaft, and a dial bore gauge to measure the bearing, then determine the clearance from doing the math. You will not be able to "percieve" this clearance by moving parts around, and this is likely not your issue.

2. Radial play of the aux shaft pulley. You stated that with the aux shaft installed, oil pump installed, and the oil pump drive gear installed, you can rotate the aux shaft pulley back and forth about 1/8" inch. The play you are feeling is the gear mesh between the gears on the aux shaft and the gears on the oil pump drive gear. If the gears on the aux shaft and the gears on the oil pump drive gear do not show signs of excesive wear, AND your oil pump tolerances are within specifications then there is not a problem and the gear mesh clearances are normal.
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Re: Slight play in Aux shaft gear?

Postby vandor on Thu Jun 28, 2012 10:59 pm

>2. Radial play of the aux shaft pulley. You stated that with the aux shaft installed, oil pump installed, and the oil pump drive >gear installed, you can rotate the aux shaft pulley back and forth about 1/8" inch. The play you are feeling is the gear mesh >between the gears on the aux shaft and the gears on the oil pump drive gear.

What I understood is that the gear moves left and right 1/8", not that it turns 1/8", but I guess that makes more sense.
Sure, if it has 1/8" free play turning it, than that is fine. But radial play means play along the radius, which is not turning a shaft, but moving it sideways.
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Re: Slight play in Aux shaft gear?

Postby Fiat88 on Thu Jun 28, 2012 11:53 pm

Yeah sorry for the confusion. I can turn it left to right. Guess I'm good then :lol:
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