Pinion seal leak, 2019 Silverado 1500 SU7 axle.

[z71offroader83]

So I have a pinion seal leak on my 2019 Silverado LT. It has the SU7 axle and only 46k miles. I DIY all my own maintenance and minor repairs and prefer to do this myself. Any instructions, advice or tips are appreciated.

The only torque spec instructions I’ve found after installing a new pinion seal are as follows which came from a GM shop manual:

USED BEARINGS
Tighten the pinion nut, in small increments as needed, until the torque required to rotate the pinion is 0.40-0.57 Nm (3-5 lb in) greater than the torque recorded during removal.

I’ve been told elsewhere that I need to record the rotational torque of the axle, then when installing a new pinion nut I add 3-5 lb in to that to tighten the pinion nut. But these instructions appear to tell me to record the torque required to remove the pinion nut. Maybe I’m understanding that wrong. Also if anybody has the torque specs needed to reattach the bolts for propeller shaft, that would be great.

 

[bdcardinal]

I am not a GM person outside of owning one, but on the Ford side of things, there are a fer rear ends where they want you to record the turning torque prior to disassembly. Also at least in Ford land, the pinion nut and driveshaft flange bolts are one time use and should be replaced.

 

[D60]

People go round and round (no pun intended). I'm personally only TRULY confident in doing this with the axles and carrier removed. If you want to be lazy, just remove the axles and assume rotational torque of the carrier bearings and friction at the R&P stays identical.

If you're extra lazy and refuse to remove the axles, remove drums or calipers or you're potentially measuring brake drag.

Based on your instructions it sounds like this is not a crush sleeve axle. If it is, start from scratch with a new crush sleeve, or get a crush sleeve eliminator kit.

Anything less is ‐‐IMO‐‐ excuses for flat rate techs to save time and know that you're probably OK.

46k ain't a lot so whether you use new bearings is up to you. New aftermarket might be worse than OEM with 46k.

Conversely, I've never torqued d/s bolts or replaced Ford's alleged one-time use bolts. So, the first part of my reply might make you think I'm crazy anal but really I just think some things are REALLY important and some things don't matter much (shrug)

 

[Kestas]

Be ever so careful with the sealing lips of the new seal. I've examined many axle seals returned from warranty. It doesn't take much damage to create a leaker. Very often the damage comes from sliding the seal over the shaft splines.

 

[bdcardinal]

Be ever so careful with the sealing lips of the new seal. I've examined many axle seals returned from warranty. It doesn't take much damage to create a leaker. Very often the damage comes from sliding the seal over the shaft splines.

I love how certain Ford/Motorcraft seals come with an installation tool that protects the seal from the splines.

 

[CarbonToast]

Can you mark the nut so you install it back in the same position? That is the process I used on my F150. It doesn't seem practical to measure such a small torque range.

 

[z71offroader83]

I am not a GM person outside of owning one, but on the Ford side of things, there are a fer rear ends where they want you to record the turning torque prior to disassembly. Also at least in Ford land, the pinion nut and driveshaft flange bolts are one time use and should be replaced.

The pinion nut is not reusable. Not sure about the flange bolts.

Can you mark the nut so you install it back in the same position? That is the process I used on my F150. It doesn't seem practical to measure such a small torque range.

According to GM the pinion nut has to be replaced. Otherwise I was going to do just that. Maybe I can count the threads.

 

[spasm3]

Be ever so careful with the sealing lips of the new seal. I've examined many axle seals returned from warranty. It doesn't take much damage to create a leaker. Very often the damage comes from sliding the seal over the shaft splines.

I love how certain Ford/Motorcraft seals come with an installation tool that protects the seal from the splines.

Sounds like it might be worth it to tape up the splines, if you don't have the above tool.

 

[clinebarger]

You take a preload reading before removing the pinion nut....Adding preload ensures you don't have to little preload.

 

[CarbonToast]

The pinion nut is not reusable. Not sure about the flange bolts.

According to GM the pinion nut has to be replaced. Otherwise I was going to do just that. Maybe I can count the threads.

Marking it and reusing it ensures you maintain the same pre load as factory. If you want to add some loctite or thread sealer, you can. I reused the nut and it's been fine for 40k miles.

 

[z71offroader83]

Marking it and reusing it ensures you maintain the same pre load as factory. If you want to add some loctite or thread sealer, you can. I reused the nut and it's been fine for 40k miles.

I was leaning towards just doing this. What strength of loctite or thread sealer did you use?

 

[Chris142]

The pinion nut is not reusable. Not sure about the flange bolts.

According to GM the pinion nut has to be replaced. Otherwise I was going to do just that. Maybe I can count the threads.

It's a lock nut. You can re stake it to re use it.

The diff likely contains a crush sleeve. I would stake and reuse the original nut before I would try to measure the preload with a scale.

Less likely to get it too tight or too loose if you mark the original nut and reuse it .

 

[clinebarger]

I was leaning towards just doing this. What strength of loctite or thread sealer did you use?

Make sure the pinion isn't already loose...Causing the leak. I use Red Loctite with a new Pinion Nut.

 

[D60]

If you're gonna go Q&D then reuse the pinion nut. Scribe a line across the face of the shaft and the nut. When you put it back put it about one "line width" past where it was. If anything you wanna add a touch of preload to compensate for worn bearings as they were set up new (obviously)

 

[z71offroader83]

Make sure the pinion isn't already loose...Causing the leak. I use Red Loctite with a new Pinion Nut.

If it was loose, wouldn’t that cause a driveline vibration of some sort?

 

[Ursatdx]

Please check fluid level. I've seen similar leaks that were caused by an overfill in the axle.

 

[z71offroader83]

If you're gonna go Q&D then reuse the pinion nut. Scribe a line across the face of the shaft and the nut. When you put it back put it about one "line width" past where it was. If anything you wanna add a touch of preload to compensate for worn bearings as they were set up new (obviously)

Yeah I’ve seen plenty of videos of guys doing just that on Fords and GMs. Looks to be the most fool proof way to make sure it’s on right.

 

[ms21043]

To get the correct pinion rotational torque, the carrier needs to be removed. If you're going that far, get a new crush sleeve and replace it along with a new nut. The sealing surface where the pinion seal rides is on the pinion flange, no need to worry about protecting the seal from the spline. You should also closely inspect the pinion bearings and races at this time. Just before installing the pinion flange, put some sealer on the splines inside the pinion flange to keep oil from seeping through the splines. Crank the nut on, you'll need some way to keep the pinion from rotating while you torque. To get the sleeve to start crushing you'll have to put a LOT of torque on it, the torque becomes a bit less one the sleeve starts to crush. Go slowly and measure the preload as you crush the sleeve a little at a time.

 

[D60]

To get the correct pinion rotational torque, the carrier needs to be removed. If you're going that far, get a new crush sleeve and replace it along with a new nut. The sealing surface where the pinion seal rides is on the pinion flange, no need to worry about protecting the seal from the spline. You should also closely inspect the pinion bearings and races at this time. Just before installing the pinion flange, put some sealer on the splines inside the pinion flange to keep oil from seeping through the splines. Crank the nut on, you'll need some way to keep the pinion from rotating while you torque. To get the sleeve to start crushing you'll have to put a LOT of torque on it, the torque becomes a bit less one the sleeve starts to crush. Go slowly and measure the preload as you crush the sleeve a little at a time.

I always order two crush sleeves. If you have both, you won't need the second one.

Typically they're inexpensive but I just ordered some for a Tundra rear and they were over $25 ea, which I thought was stupid

 

[D60]

Yeah I’ve seen plenty of videos of guys doing just that on Fords and GMs. Looks to be the most fool proof way to make sure it’s on right.

Nah, it's a shortcut that works most of the time.

Also, if this leak isn't bad I'd leave well-enough alone and try some dino 85-140