Howto check compressor gear nut

[Plasa]

Hello forum.
What is the best way to check the compressor gear nut? It's a common issue and I wonder if it's usefull to check it once per year. But do I need to remove the hole compressor to check the nut, or it's enough the remove the front housing cover?

Thanks a lot and best regards from Italy!

Christian

 

[Suprman]

I have never seen the compressor drive loosen up. The rear support bracket can come loose and cause damage to the front cover from the weight of the compressor and steering pump.

 

[Plasa]

OK, maybe I disunderstand the first point of the very valueable PDF of the 3116 failure points, the Compressor gear nut loose.

I though it was the nut that holds the gear in place... Not the bolts that old the compressor in place to front housing and bracket...

Christian

I have never seen the compressor drive loosen up. The rear support bracket can come loose and cause damage to the front cover from the weight of the compressor and steering pump.

 

[Coffey1]

Un bolt front cover
You don't need to totally remove cover, it will pull back enough to check nut or change.

If you find tight I wouldn't do anything but put on a schedule to look at it some time in the future

If loose replace it with a lock nut.

Mine came off ! Nut was laying in bottom of cover, gear slid forward. I put nut back on thinking I had missed a bullet.
Not so lucky valve on compressor went through piston

Lots and lots of hunting and 800 bucks later back on road

 

[Reworked LMTV]

Anyone know the torque spec for that nut, so I can add it ?

 

[Third From Texas]

Wasn't there a bulletin about changing to a locknut or something?

 

[Coffey1]

Yes there was but if it's super tight, you know the old saying don't screw with it

 

[Reworked LMTV]

125# torque x 2.

See Link below:

http://www.catengine.info/workshop/...compressor-drive-gear-remove-and-install.html

Anyone know the torque spec for that nut, so I can add it ?

 

[tennmogger]

That's a good link, thanks!

There seems to be a mistake in step 2, should be remove nut 4 (not nut 2).

And why do they say to torque the nut twice, before then after whacking the tool with a hammer? Of course we won't have that tool.

125# torque

See Link below:

http://www.catengine.info/workshop/...compressor-drive-gear-remove-and-install.html

 

[Reworked LMTV]

Never ever tell a SS member to use a hammer

That's a good link, thanks!

There seems to be a mistake in step 2, should be remove nut 4 (not nut 2).

And why do they say to torque the nut twice, before then after whacking the tool with a hammer? Of course we won't have that tool.

 

[Awesomeness]

And why do they say to torque the nut twice, before then after whacking the tool with a hammer? Of course we won't have that tool.

I think it's because that guide is actually about removing the gear, not just replacing the nut. So they want you to bolt the compressor back on to hold it well, then you make sure the gear is hammered on completely, then retighten the nut in case the gear moved onto the shaft more.

It would be good to get a part number for the nut, along with a description of what it is (e.g. thread diameter and pitch). I've been on the lookout for it for a while, but haven't seen anyone change one out to ask.

 

[SausageGuy]

It would be good to get a part number for the nut, along with a description of what it is (e.g. thread diameter and pitch).

Per TM
35 PAFZZ 96906 MS51968-23 NUT,PLAIN,HEXAGON 3/4-16

 

[Awesomeness]

Per TM
35 PAFZZ 96906 MS51968-23 NUT,PLAIN,HEXAGON 3/4-16

Then I would recommend McMaster part number 90040A150, "Center-Lock Distorted-Thread Locknut, Low-Strength Steel, Grade 2, Zinc-Plated, 3/4"-16 Thread Size"
https://www.mcmaster.com/90040a150

This is an educated guess, and has not been tested yet. The -24P TM lists the original nut as:NUT,PLAIN,HEXAGON 3/4-16

So this McMaster part number is also a 3/4"-16TPI nut. Looking at pictures of the gear on the front of the compressor, it doesn't look like there are many extra threads to support a standard style nylon locknut. So this McMaster part number has locking features without being longer than a standard nut. They have low-strength and high-strength varieties, and it's important to match to the bolt (in our case, shaft), but we don't know what that is. So choosing the low-strength option means the nut should be damaged before the shaft is. Even a low-strength nut should be fine at retaining the gear, since the design doesn't experience axial forces in operation. Grade 2 bolts are 74,000 psi steel.

If someone tries it, please report back if it worked.