I had the pinion seal replaced on my '72 Supreme and after driving it today, I find it's still leaking. What now???

 

Dave - Is the leak about the same as it was before you had the pinion seal replaced, a little better than before it was replaced, a little worse or far worse?

 

Mmm...I'd say maybe a little better Norm.

 

Is it leaking around the seal or pinion splines?

 

Haven't dug that deep... all I know is I have a small film of diff lube on the bottom of the center housing coming and from the yoke, and a drop on the housing under the diff cover and on the rear sway bar.

 

Had a newer seal appear to be leaking not long ago, it was leaking between the splines and the yoke not the seal.

 

Gotcha...how did you fix it?

 

Remove the yoke, clean the splines on the pinion, in the yoke, put a small amount of sealer on the splines and reinstall the yoke.

 

So that would involve removing the new seal and installing another one, correct?

 

No, the seal will stay in place.

 

I'm having trouble wrapping my mind around this...if the seal will stay in place, then that means the seal is behind the yoke, correct? If that's the case, then how would the fluid be leaking through the splines?

 

Yoke OD slides into the ID of the seal

 

Can anyone please provide a diagram or a picture? I'm really not visualizing this...

 

https://www.speedwaymotors.com/the-t...ructions/30079

 

The pinion seal that was replaced goes around the outside of the yoke. If the splines are the leak, the leak is on the inside of the yoke. The gear oil is getting between the splines where no seal exists. The sealer becomes the inside seal.

 

Dave - Find a video demonstrating removal of the rear yoke & you'll gain an understanding of the location of the pinion seal relative to the splines. Scribe/Mark position of the nut prior to disassembly. It's a good idea to use a new washer & a new nut to secure the yoke on reassembly.

 

So if the lube is leaking around the splines, then what's the point of the seal? Isn't the seal supposed to prevent this from happening?

 

The seal between the yoke and housing prevents oil from slipping past the OD of the yoke, it does nothing to prevent oil from slipping between the splines on the OD of the pinion and the ID of the yoke and then making its way up and around the head of the nut that clamps the yoke to the pinion.. That is what the sealer on the splines is for.

Looking back to when I rebuilt my Type-O ~18 yrs ago, I did not put sealer on the pinion splines (didn't realize I needed to), but I have only very slow seepage, a negligible amount. So I'm guessing the clearances on my assembly is tight enough to prevent a significant leak.

 

I usually smear some RTV under the pinion nut. That works well enough.

 

Is the pinion nut accessible without disassembly?

 

Define "negligible" in your case please...

 

No. You have to remove the driveshaft from the rear yoke by loosening/removing the rear U-Joint clamps.

Loosen (or remove) the nuts/bolts (can't recall which on this car) holding the rear U-Joint to the rear differential yoke. With a crow bar pry the propeller shaft away from the rear differential yoke. This will reveal the pinion nut.

There are many videos. As I suggested (Post #16) review a video. Have you reviewed the procedure diagram(s) in the CSM?

Here's a basic video.

 

Wetness without drips.

 

Ok...so here's where I am. I don't really want to pay the shop to take it apart again, and I don't have a convenient way to do it myself. If I just have a drip or two, and since I've already had the seal replaced, and if I keep an eye on the fluid level, is it really that much of an issue?

 

Dave - No one sitting on the other side of an Internet connection can visually "see" what you see. We aren't magicians. That answer is entirely up to you. Make sure you have the differential filled completely right to the bottom of the opening. Just keep an eye on it. You were missing a vent tube as I recall & you addressed the missing vent tube - that's good. Finally, in this thread unless I missed it, I don't believe you've convinced yourself or others "this" oil leak comes from the yoke spline - you haven't convince me anyways. Hell, it could still be coming from the pinion seal they just replaced - was it installed ****-eyed, did they screw-the-pooch elsewhere on the pinion seal R&R? Who knows. If it isn't puking oil, put a turkey tray under the rear end & call it a day.

 

I'll check the level and go from there Norm. Also, I just thought of another question.. whether it's the seal that's still leaking or if it's leaking around the splines, would one (or both) scenarios be a static leak or a leak only when I'm driving?

 

My perspective says it depends. Perhaps under heat you might suspect more of leak - maybe so. I think it's likely a toss-up to be honest. Sorry.

 

My opion. Take it back to the shop the" fixed " it, Tbey should have put sealer on the splines. If that is in fact where is is leaking. If they installed the seal incorect the leak will get worse. Im sure there is a time limit on any work warrenty 1 or 2 drops of gear oil slung over the bottom of you car is going to creat a nsty mess. NOTHING holds road dirt better than gear oil

 

One thing that I have not seen addressed here is the possibility of a wear groove on the outside of the pinion yoke where the pinion seal contacts. It is not unusual to find a wear groove on our older high mileage vehicles. The shop that installed the seal should have notified you if such is the case and offered suggestions to repair it. Repair sleeves are available, I don't know how effective these sleeves are or how long lasting they may be. Also if the groove is not too deep it can be machined out on a lathe and polished. The last resort is replacing the yoke.

 

I talked to the shop today that did the work, and they checked the yoke for any grooves (it was good), and they did use rtv on the splines.

 

Ok, so further diagnosis revealed that there was too much fluid in the differential. Enough to when I removed the fill plug, it started draining immediately. I let it drain for about 30 minutes until I saw no more fluid running down onto the housing. When all was said and done, I probably had about two ounces that drained out. I'm hoping that was the issue and that I didn't wreck the new seal from driving it with too much fluid. I've only driven about 200 miles since I had seal replaced, so hopefully I'll be ok.

 

An overfill can be the cause, monitor it and see how it goes. Do check it on level ground.

 

Um...that's gonna be difficult as my rear sits higher than the front. I've always checked it in my driveway by dipping my pinky in and as long as I get fluid I've always called it good.

 

Dave - There should be no (zero) pressure inside the differential housing - nada. If you're filling the differential as you state, there shouldn't be any fluid running out of the fill hole. I know you didn't have a axle vent for I don't know how long (?). You installed a new vent as I recall. Ensure the axle vent hole itself is not obstructed & ensure the vent clear, free of debris & mounted correctly. Heat created inside the differential housing needs to vent so as not to create any pressure. Any pressure created can increase temperature & create moisture. Ensure the vent is clear & operational it "could" be why fluid exited the fill orifice when you opened it. You didn't hear any pressure release when you removed the plug hopefully - if so, check the vent.