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MG TD TF 1500 - Rear brake drum wet = bad oil seal?

I pulled the left rear drum off to rebuild a leaking brake cylinder (dripping on ground) and I discover the entire inside of the drum is wet and VERY dirty. Can I assume that means the seal at the outer end of that halfshaft is shot and is allowing fluid into the drum and getting on everything?

Anything else it could be?


"Fun times aren't around the corner, they're in the corner."
Stan Griffis

If you cant tell if it is brake fluid or hypoid oil, I think I would change the seal, check the bearing and make sure the small breather hole on the top of the axle housing is open and not covered with grime, dirt, etc.
Jim Merz

Two things.

a) how big of a deal is a seal change (and should I do anything else preventative in that area when I change out the seal?)


b) Where is this breather hole in the axle tube? Inner, outer, etc...
Stan Griffis

When working on the brakes anyway, changing the seal is not that much more. Remove four bolts retaining the backing plate and remove it. The bolts also hold the bearing housing and oil seal. The seal comes out with the housing.
The breather hole to vent built up oil pressure is located on the top of the LH axle tube about 1 1/2" from the center housing. Its a 1/8" hole that many times gets covered with years of grime, etc. When the axle builds pressure with the vent clogged, the oil is forced past the seals.
If you feel like pulling the half shaft, then you should also look at the axle splines to check for any signs of twisting. The axle shaft will come out with the bearing. A slide hammer is useful in removing the axle. The axle splines in the center gear housing are the most likely to twist/break. This is a known weakness in the TD/TF axle half shafts.
Jim Merz

If the half shafts are pulled, it would be a good time to drill out the vent hole and install a axle vent for the MGBs. Besides having a hole big enough to keep from getting glogged, it has a jiggle cap on the to keep out dirt and still keep the vent open. Good luck - Dave
David DuBois

Do I have to pull the axleshaft to replace the oil seal, or is it replaced once I get the 4 bolts from the backing plate removed w/o removing the shaft?
Stan Griffis

Stan I think the answer to your question depends on how tight the bearing fits in both the axle housing and the bearing housing. Since the bearing is a very tight fit, normally requiring a press to install on the shaft, it will probably stay on the axle shaft. If the bearing fits equally tight in the bearing housing then when you pry it loose, you will either get the bearing housing, axle, seal and bearing in one hunk. Or more than likely, the bearing housing and seal may just separate from the bearing and axle assembly. The backing plate is removed from the axle housing before you can gain access to the bearing housing.
Jim Merz

Stan, you do not have to remove the backplate, housing, axle or anything to change the seal. Just remove the drum, remove the split collar, and pry the old seal out. However, as you are just about into the axle, you really should pull it (as above), and really look at the inside splines (trust all of us!). If it is an orig. axle, it will be really twisted. If so, do the other side also. If the housing comes off leaving the axle/bearing, put the washer/nut on (or even the drum), and tap it outward- this has always worked for me. Be sure and use gasket sealer (sparingly) on the housing to axle interface when reassembling.
George Butz

Thanks for the tip on the breather hole, it was definitely clogged. Finding it would have been impossible w/o the advice from the board here.

The axle spline referenced above, can I assume by this you mean the "gear" at the differential end of the axle? Is there a picture somewhere of what kind of twisting I'm looking for? I assume a good set of splines has all the gears running parallel to each other and that worn ones, well, don't.

Thanks for all the advice (so far). I'm getting worried that such a disproportionate number of the recent "how/what" posts are from newbie-me.

Stan Griffis

Stan, no one is born knowledgeable about the peculiarities of the XPAG engines and the TD running gear. These responses are just sharing the results of "been there, done that". We are here to help and glad to do it.
Jim Merz

The raised ridges and valleys should be straight. When they twist, they are just that- cracked and twisted- like the end part will be offset, sometimes a lot, and no longer in a straight line. It is very obvious. To check for wear, (this happens at the drum end), they should be the same width from the base (the untouched/unworn part) to the end. Again, it will be obvious.
George Butz

After removing the brake backing plate I don't see how to remove the conical slotted spacer that id outboard of the seal. Also, the seal on this axle seems to have been dressed with a rubber gasket looking material around the outside edge, and lopks very solid, as though maybe I'm not leaking fluid from the axle after all.

I'm wondering if I want to get in there if it looks like there couldn't be a leak past this rubber gasket-like material (permatex?)
Stan Griffis

This thread was discussed between 29/08/2003 and 01/09/2003

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