R180 Differential leaking - what to check?

[7T1240]

Last weekend, before putting the car away for winter, I took it to a self-serve car wash to do some detail cleanup on the inner fender wells. While I was there I decided to blast off the accumulated gunk on the cover plate for the rear diff. The accumulated gunk appeared to be mostly around the seam between the cover plate and the diff., and then back onto the cover plate.

This started me thinking about maintenance for this component. At first blush I would think to drain and replenish fluid, and check torque on the cover plate bolts. To go one step further might include removing the cover plate and replacing the gasket.

Are there other leak sources I should be looking for? Any other tips or suggestions? (Car has about 83,000 miles on it...'71 series I.)

Gary S.

[dzrt1st]

In addition to the cover gasket there are several leak sources on the differential. There are oils seals on each side where the halfshafts enter the housing. There are rubber o-rings on the side bearing retainers that could leak.There is an oil seal at the front of the housing (pinion seal) behind the drive shaft companion flange. The drain and fill plugs could leak if they aren't tight enough. Oil can leak out the vent at the top if its installed wrong or if the diff is overfilled.

You can't change the cover gasket without pulling the differential since the cover bolts directly to the mustache bar.

Todd

[rtaylor]

I pulled my cover without removing the differential. All I did was remove the mustache bar and then I was able to gain access to the cover plate to replace the gasket. 71 240

[7T1240]

In addition to the cover gasket there are several leak sources on the differential. There are oils seals on each side where the halfshafts enter the housing. There are rubber o-rings on the side bearing retainers that could leak.There is an oil seal at the front of the housing (pinion seal) behind the drive shaft companion flange. The drain and fill plugs could leak if they aren't tight enough. Oil can leak out the vent at the top if its installed wrong or if the diff is overfilled.

You can't change the cover gasket without pulling the differential since the cover bolts directly to the mustache bar.

Todd

Hi Todd, thanks for the checklist.

Have you gone through one of these and renewed the seals and gaskets? If so, is this a home mechanic with hand tools job? Sounds like I need to get the car up in the air and just have a good look-see. BTW, where's Mckenna?

I pulled my cover without removing the differential. All I did was remove the mustache bar and then I was able to gain access to the cover plate to replace the gasket. 71 240

rtaylor, thanks. This is helpful in the event that only the fluid change and cover gasket need to be addressed.

Gary S.

[dzrt1st]

Gary,

The side seals and the rear cover gasket can be done relatively easily with small hand tools. The pinion seal in the snout is a bit more difficult. You'll need a 27mm socket and breaker bar or an impact wrench to remove the nut on the pinion shaft, it's torqued to 120-140 ft lbs. Once you get the nut off you may have to use a puller to remove the companion flange.

I put the diff on my bench with the companion flange in a vise and used a breaker bar to break the nut loose.

The old seals pry out of their locations fairly easily with a screwdriver. The new seals are tapped in with a hammer. I used the old seals placed over the new seals when tapping them in to protect them from the hammer.

I bought new seals and the cover gasket from the dealer.

FYI, McKenna is about 20 miles south of Tacoma and about 20 miles NW of Olympia.

Todd

[zztom]

Is this the same area where that whining sound comes from when you get on and off the gas? It sounds gear related but I could never pin it down.

[cegrover]

The old seals pry out of their locations fairly easily with a screwdriver. The new seals are tapped in with a hammer. I used the old seals placed over the new seals when tapping them in to protect them from the hammer.

I know this is an old thread, but I have a related question. I bought new side seals for my R200 and they do not seem to be a tight fit. The old ones I had to pry out, but the new ones are clearly smaller in diameter and are loose.

Are there different diameter seals for R200 differentials? My car is a '75, but this diff is a 3.90:1 R200 from an 82 or 83 280ZX. I ordered seals for a 1982 280ZX...

[cegrover]

Note: I think I found the answer on another forum and some seals sold as R200 units are actually for R180, which means a different diameter. I have correct ones on the way, and will confirm here once I know they actually fit!