Pinon Seal Leak

[donl]

Pinion Seal, I can spell.

2003 Expy. Started leaking at 140K miles; seal has been replaced twice by a local independent shop. First seal was replaced in October last but started leaking again this past January. Second seal replace under warranty about two weeks back and leaking again but not as bad. I suspect the seal is not leaking at the lip but at the outside between the seal "shell" and the bore. Is this a common issue? What is the cure? RTV sealant? Doesn't seem like that would last long. Suggestions appreciated.

 

[1955moose]

Well 2 scenarios come to mind. 1 the person installing seal is not installing it right, tearing lip while installing it, or installing it dry, or 2, you've got a burr, or sharp edge on pinion shaft. Actually theirs a third, the seals themselves are sub par quality, and are failing premature. Maybe this third go round bring your mechanic a oem Ford one from the dealer. Pick it up yourself. I'm sure your guy doesn't want to eat his labor a second time. When I managed a Honda, Kawasaki dealership aways back, my mechanics would not change front fork seals, unless they were OEM. They worked on commissions, so a comeback was never an option, and I never challenged that. Let us know how it turns out.

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[stamp11127]

1) low quality seals
2) groove on yoke where the lip rides
3) no sealant between seal and housing
4) vent plugged allowing pressure to build up in rear end when hot
5) worn pinion bearing allowing yoke to wobble when spinning

 

[1955moose]

That's why your the professor!

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[donl]

1) low quality seals
2) groove on yoke where the lip rides
3) no sealant between seal and housing
4) vent plugged allowing pressure to build up in rear end when hot
5) worn pinion bearing allowing yoke to wobble when spinning

Actually, there is a bit more information I left out of the first post because I didn't think it relevant but several of the causes listed above were considered with the first seal replacement which I did before taking it to a shop.

I am a bit of a gearhead and have been wrenching on a variety of machines since I started handing my Dad tools when he was making vehicle repairs back in the '60s. I have replace a variety of seals in a variety of machines from Caterpillar heavy equipment, to Chevy and Ford vehicles, a variety of off and on road motorcycles, etc., so I felt quite competent to replace this pinion seal.

As was pointed out to me before taking on the repair, the seals are a bit of a pain to install so when the first seal I replaced started leaking after, I am guessing now, less than 5K miles, I figured I must have screwed something up. However, I did not use an OEM seal nor did I apply any sealant between the outside of the seal and the housing bore but I did check the yoke for a groove and found none and I did check the vent and found it open. I doubt that the pinion bearing is worn enough to allow the yoke to wobble at 149K miles but it is something to check out.

That is when I decided to take it to a shop where someone that had replaced more than one of these seals might be more successful. I am pretty sure the tech did not use an OEM on either replacement as his shop is associated with Advanced Auto and that is his parts supplier. I do believe he applied sealant (not sure which one) to the outside of the seal and housing bore as the second seal he replaced does leak but does not appear to be leaking as bad which is why I suspected that is where the seal is now leaking but that is speculation on my part.

So, I will pick up an OEM seal as has been suggested and review all of the above referenced potential sources of the problem to the tech when I return the vehicle to him. He did ask that I bring the vehicle back in after a couple of weeks so I am pretty sure he intends to solve the problem one way or another.

Thanks for the suggestions.

 

[deweysmith]

My brother-in-law did mine for me with a non-OEM but reputable part (I wanna say Fel-pro but I don't remember) and no sealant, just lubed it up a bit before tapping it in. It's still good a whole oil change later.

 

[stamp11127]

The yoke nut is used to pre-load the pinion and crush sleeve. Make sure it is torqued back to spec and not just hit with an impact.

 

[deweysmith]

It's complicated to torque, too. You have to tighten it and use a gauge to measure how much torque it takes to start rotating the pinion and stuff… it was a fun time in the shop, let me tell you.

FordTechMakuloco says you can simulate this by counting threads, but I would feel better about measuring the preload precisely, especially if not doing so caused a continued leak.