How does axle seal work?

[Vikas]

A very long story but I need to understand how same side axle seal can still leak after:-

1) Changing the CV joint
2) Changing the transmission

Essentially the seal which mates the two parts have been changed and the leak is still there and of course the seal itself has been change too :-(

We are talking about two different mechanics (two shops in two different states) here.

Are all the mechanics just not really careful in installing the seals? Please explain the theory behind the oil seals. How does it work and what are the stupid things that installer can do to cause it not to seal.

 

[Rand]

installation damage or defective part.

 

[hisilver]

From my very limited axle seal servicing; if upon removing the old seal the surface where it seats is scored, all new seals will either tear or not seat properly. Perhaps that's the case?

 

[Cardenio327]

Sometimes on axles, shafts, &c., the seal wears a groove into the shaft or axle and a simple seal replacement will still leak. There are repairs available that involve bonding a sleeve to the shaft and using an oversize seal and others that relocate the lip of the seal to an undamaged surface of the shaft.

Make/Model would make it a little easier for specifics.

 

[Vikas]

2000 Maxima 5-speed

As I said in my original post, both the axle and the transmission was replaced (I am assuming mechanic replaced the seal too). The seal is between the axle and the transmission. When the transmission was replaced, would a mechanic remove the old seal from the old transmission and reinstall it on the next one?

Please correct me if I am wrong. Oil seal is stationary, right? Only the shaft inside spins. It is constantly rubbing against the rubber. How in the world it is supposed to keep oil from leaking???

 

[eljefino]

When you got the used tranny you probably got the used seal that was on it. Look over your receipt if you have it; they'll probably itemize if they did bunches of little parts. IE did they charge for fluid?

When I did a seal on my saturn, I wiped the trans case down with a brake cleaner rag to get remnants of fluid then coated the new seal with RTV on its mating surface just in case there was a nick in the aluminum trans case. Probably paranoid but it didn't leak. Who knows what the tech did?

A seal has to lubricate itself to work, so it will weep a little fluid. But if it drips on your driveway it's not a weep, it's a leak.

 

[Vikas]

You are right. On the itemized list, there is no axle seal listed but the transmission oil is listed.

It is a leak as it is drips on the floor when parked.

Coming Saturday, he will replacing the oil seal. I have asked the mechanic to make sure he gets correct one from the dealer specifically made for this car+transmission and asked him to use the VIN number.

I think it is leaking from where the axle goes in. At least that is how it used to be before all this drama happened. The RTV would not help there, right??

 

[mechtech2]

The seal has nothing to do with the trans or CV joint.

It is for the wheel bearing.

Or are you talking about thee trans seals for the axles?

 

[Kestas]

I see transmission/transaxle/and transfer case seals quite often that come in from warranty. A very common defect is poor installation where the shaft splines are dragged against the seal. This can happen during removal and installation.

Some applications are left/right specific. If it's installed in the opposite position, you'll have a peretual leak problem. These seals have helixes adjacent to the primary seal.

As mentioned, always install the seal wet with the parent lubricant.

Originally Posted By: Vikas
Please correct me if I am wrong. Oil seal is stationary, right? Only the shaft inside spins. It is constantly rubbing against the rubber. How in the world it is supposed to keep oil from leaking???

It's magic.

 

[Trav]

Question. Is the leak from the rubber portion of the seal or from the metal part that goes in the housing?
At times they will leak here, all it takes is to coat the metal lip with some good old Indian head shellac after cleaning the case part with brake cleaner.

 

[Vikas]

I am talking about the trans-axle seal. The seal is put in to the transaxle (rather in to differential end). There is one for each side. After the seal is put in, the drive axle is then pushed (snapped) in. Whenever I have seen it, it leaks where the axle enters the transaxle. The seals are different for driver and passenger side. The last two times, we had put the Nissan seals.