Rear differential leak repair

[Joel]

Hello,
Anyone care to estimate the labor hours needed (or cost) from simple to extensive, to repair a slowly leaking rear differential on a 1968 280SL?
Thanks,
Joel

[Ed Riefstahl]

Hi Joel,
My guess is the boot is leaking. I've encountered this a couple of times when the old flex boot gets old. I replaced the boot on my 66 230SL a few years ago with a split boot. Now I'm getting a drip from my 1970 280S. Not the ideal fix, but also much much easier and cost very little. Check to make sure it's not the pinion seal first.

Replacing the boot with a solid boot would be ideal, but I believe Dan (Dr Benz) said you really need to drop the rear axle to do the job correctly. At any rate a much more difficult job. If you're doing the job yourself, it's no that difficult just messy. I found that you can seal and clamp the split boot seam, then rotate the boot to the top and tighten the band clamps.

Good luck,
Ed Riefstahl
Erie, PA

1966 230SL (Ms Magoo)
1970 280S (Miss Daisy)
1989 300SE (Majestic)
1999 BMW Z3 5 speed
1991 BMW 318I 5 Speed
1997 Toyota Paseo Convertible - Red 5 speed (have you ever seen one?)
1997 Ford Ranger (Step Side 54K)
2012 Toyota Rav4

[Benz Dr.]

No, leave the split horizontal to the ground. Placing the split at the top can make it tear apart. It's also helpful to remove the fuel tank to allow for more room to work.

[merrill]

Joel
hi,
been there done that
with the help from this forum and manuals i pulled the rear axle on my 66
replaced solid boot, pinion seal,  had brake drums relined and re shoed, new brake pistons, brake rubber hoses,   etc.

i took my time, its a pain but not super difficult.

as far as i know the original boot lasted 50 years

[ejboyd5]

I believe when Benz Dr. states, "leave the split horizontal to the ground," he is confirming the usual practice of placing the split so that it either faces forward or toward the rear of the car, not to the top or the bottom side of the axle. This orientation minimizes stress on the assembled seam when the axle moves up and down.
Although a leaking boot is a logical guess as to the cause of the problem, may I suggest a thorough cleaning of the area to confirm that it is a boot problem rather than something else.

[ja17]

You will notice that the folds on the axle boot are deepest on one side. Orient the deepest folds of the boot up and you will see that the seem orients basically horizontal. I have the factory clip crimp tool. I usually crimp the seam together then rotate the entire boot into correct orientation before installing the special "skinny" clamps. Some years ago, I also made a special tool which works at 90 degrees, so I can install all the clips easily without removing the fuel tank!

[Joel]

Thank you all (ja17, ejboyd5, merrill, Dr. Benz, and Ed Riefstahl for taking the time to weigh in on a leaking rear differential.  Your knowledge of this Pagoda problem is impressive.  Unfortunately, I'm not a do-it-yourselfer.  I have a competent mechanic who will repair it, but at great expense.  My former mechanic, now retired, suggested to just keep an eye on the fluid level.  As long as the leak is slow he said the fluid will last an entire summer driving season.  He also added, "old cars leak, almost all of them do, there's a strong chance it'd leak again, even after being repaired," and he also suggested, "don't park on your friends' driveways".  Point taken.
So in the end the differential area was merely degreased to pinpoint the leak; and I've stored the car for the winter. 
Again, thank you very much.