Recurrent pinion seal leak

[calebdnehus]

Anyone here had issues with a recurring rear pinion seal leak? Mine failed around 33k miles, got repaired. Truck came back with a vibration/whine around 40mph. Took it back, they broke it down and replaced the pinion bearing and related parts along with another new seal.

That held for about 9k miles before the seal started leaking again. Dealer one again repaired the leak and I have the truck. As far as I can tell, the diff is still quiet and without vibration (tires are getting worn so I’m attributing what tiny bit of noise I can hear to them).

My question is the title, is anyone else having this recurring problem? I’ve checked the forum and seen very similar situations but no mention of multiple failures in end and how they were resolved. Cornered that a 2022 truck with 44k miles is giving these type of problems.

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[FaaWrenchBndr]

Really need to clean the diff housing and the seal then get a good picture where the diff fluid is leaking from. Often it can be leaking from between the seal and the housing itself self. The housing can have a casting inclusion or a gouge from removing the previous seal.

 

[Gutshot]

Yes
I had mine serviced at 26K by the dealer I purchased it from.

Leaking again at 32K, trying another dealer closer to home with the ESP I purchased.

 

[SteelCity]

Yep. 2022 here. Just bought it used with 36,000 miles. They did the pinion seal and rear differential before I bought it. Rear differential leaked a couple weeks later so another closer dealer re did that. Then the pinion seal leaked and they changed that seal and rear diff again and now the pinion seal is leaking again a couple weeks later with the same noise around 40mph so goes back on 8/12 and I'm assuming a bearing and some other stuff in there. All under warranty so I'll just keep taking it back.

 

[calebdnehus]

So we’ve either got a bad design, bad run of parts, or incompetence in the technician making the repair. Or some combination of all three. Is this problem giving any of you pause when considering long term ownership?

I was planning to pay my truck off in a lump sum and drive it for as long as possible (hoping 10-15 years total without having to make a major costly repair) before I would consider buying another new vehicle.

 

[SteelCity]

Pinion seals seem to be a recurring common problem on these trucks. I'm not too concerned as I did purchase a premium care warranty and was able to get the price as if it was new bc it had under 41,000 miles and under 4 years from new, or something like that. I plan on keeping mine long term. If it was just weeping like most I wouldn't mind but mine does build up and drip so it needs addressed.

 

[calebdnehus]

Pinion seals seem to be a recurring common problem on these trucks. I'm not too concerned as I did purchase a premium care warranty and was able to get the price as if it was new bc it had under 41,000 miles and under 4 years from new, or something like that. I plan on keeping mine long term. If it was just weeping like most I wouldn't mind but mine does build up and drip so it needs addressed.

Mine was the same way. First seal had a decent drip puddling in my garage floor. Second one I caught before it got that bad. I may just watch it to see how it holds up closer to warranty expiration and make a call at that point.

 

[My 2ND Ford]

Really need to clean the diff housing and the seal then get a good picture where the diff fluid is leaking from. Often it can be leaking from between the deal and the housing itself self. The housing can have a casting inclusion or a gouge from removing the previous seal.

I think most comebacks are caused by incompetence more than part failure! I worked for Napa for years and you would be surprised by what a "mechanic" will try and return as defective.

 

[SALEEN961]

Repeated pinion seal leaks are usually caused by mechanics cutting corners when replacing the seal or ignoring the root cause of the failure. Insufficient bearing preload or damaged sealing surfaces can easily cause new seals to leak.

The vast majority of mechanics mark the location of the pinion nut, remove the pinion nut, pull the pinion flange, replace the pinion seal, re-install the pinion flange, and tighten the pinion nut to the marked location. This shortcut usually works, but it is far from correct and after multiple failed replacements, it isn't worth trying. This method really only works if the pinion bearing preload was correct when the vehicle came in for service, and it almost never is.

The proper procedure would include removing the rear axles and carrier assembly, removing the pinion gear, replacing the pinion bearing crush sleeve, and properly setting the rotational torque of the pinion bearings with a new pinion nut. This pays 4-5hours, but the shortcut method takes less than an hour.

 

[calebdnehus]

I think most comebacks are caused by incompetence more than part failure! I worked for Napa for years and you would be surprised by what a "mechanic" will try and return as defective.

I believe this was likely the cause of the differential issues I had after the first replacement

 

[calebdnehus]

Repeated pinion seal leaks are usually caused by mechanics cutting corners when replacing the seal or ignoring the root cause of the failure. Insufficient bearing preload or damaged sealing surfaces can easily cause new seals to leak.

The vast majority of mechanics mark the location of the pinion nut, remove the pinion nut, pull the pinion flange, replace the pinion seal, re-install the pinion flange, and tighten the pinion nut to the marked location. This shortcut usually works, but it is far from correct and after multiple failed replacements, it isn't worth trying. This method really only works if the pinion bearing preload was correct when the vehicle came in for service, and it almost never is.

The proper procedure would include removing the rear axles and carrier assembly, removing the pinion gear, replacing the pinion bearing crush sleeve, and properly setting the rotational torque of the pinion bearings with a new pinion nut. This pays 4-5hours, but the shortcut method takes less than an hour.

I believe this exact sequence you describe happened to me. Based on the service records:

2/24/25 - replaced seal, locking nut, and added grease. Got truck back, whining/roaring rear differential. Took truck back to deal on the following date.

3/14/25 - replacement parts were cup, 3 bearing assemblies, pinion spacer, seal assembly-oil, lock nut, shim, pin, axle oil. No more noise in diff. Repair holds for a while but starts leaking again. Truck returns on following date.

7/28/25 - replacement parts this time are locking nut, seal assembly-oil, bolt hex head, and rear axle oil.

The 3/14/25 and 7/28/25 repairs were completed by the same tech

 

[My 2ND Ford]

I believe this exact sequence you describe happened to me. Based on the service records:

2/24/25 - replaced seal, locking nut, and added grease. Got truck back, whining/roaring rear differential. Took truck back to deal on the following date.

3/14/25 - replacement parts were cup, 3 bearing assemblies, pinion spacer, seal assembly-oil, lock nut, shim, pin, axle oil. No more noise in diff. Repair holds for a while but starts leaking again. Truck returns on following date.

7/28/25 - replacement parts this time are locking nut, seal assembly-oil, bolt hex head, and rear axle oil.

The 3/14/25 and 7/28/25 repairs were completed by the same tech

Is the seal leaking at the rubber part or leaking between the seal flange and diff?

 

[calebdnehus]

Is the seal leaking at the rubber part or leaking between the seal flange and diff?

It’s been pretty coated both times I caught it but it appears to be leaking from what I assume is between the mating surface and the seal. I put a photo and arrow in an attempt to show it

 

[FaaWrenchBndr]

It’s been pretty coated both times I caught it but it appears to be leaking from what I assume is between the mating surface and the seal. I put a photo and arrow in an attempt to show it

And this is exactly what I was talking about. A mechanic that knows his ass from the hole in the ground, will apply a very light coating of RTV to the outer of the seal. This forms a gasket, ceiling, the damage or porosity or inconsistencies preventing a leak.

This is often done on differential opinion seals, as well as transmission tail shaft seals.

 

[calebdnehus]

And this is exactly what I was talking about. A mechanic that knows his ass from the hole in the ground, will apply a very light coating of RTV to the outer of the seal. This forms a gasket, ceiling, the damage or porosity or inconsistencies preventing a leak.

This is often done on differential opinion seals, as well as transmission tail shaft seals.

Funny you mention tail shaft, here are some photos I took of that area this afternoon

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