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Rear Differential leaking slowly + lots of build up

Started by carzilike, 25 September 2023, 04:41 PM

carzilike

Hi all, I bought a 1977 280SE (euro spec) that has slow leak from the differential. Can anyone point me in the right direction on what to do before I take it to a shop for diagnosis$?

Also the fuel filter/pump are being held by cable ties... Kind of shady. The car was definitely looked after by a farmer or something as its got lots of "diy" which doesn't fill me with confidence

I am thinking it might be smart to replace the fuel pump / filter with bosch as these look generic

The car drives fine aside from a stutter only when idling and blipping the throttle. It tends to hesitate and won't rev up as it should - its like something is cutting fuel to the engine. but when driving - its fine


daantjie

You need to clean the diff to see where it's leaking.  Could be from drain and or fill plug, cover seal or shaft seals.  Cheapest fix is the rear cover seal.  Side shaft seal would be an expensive shop rate fix as pulling the shafts is a pretty involved job.  If the leak is small you could just live with it and make sure the fluid stays topped off.
Daniel
1977 450 SEL 6.9 - Astralsilber

rumb

Also the input shaft seal.   That one can be done fairly easy by a skilled mech.  They usually mark the nut and tighten it back to the same spot. - In reality it is much more difficult as you are suppose to measure backlash.....
'68 250S
'77 6.9 Euro
'91 300SE,
'98 SL500
'14 CLS550,
'16 AMG GTS
'21 E450 Cabrio

carzilike

Here is what it looks like. The more I drive it, the more I see the diff leak. When the car sits overnight there's maybe 5-10 drops that accumulate but I don't know if the fluid has ever been changed or what fluid was used previously - the car came from the middle of no where and has signs of neglect/shortcut mechanic trickery in various areas

How do I check the fluid level? I assume it would be wise to put some fresh fluid in there? Or is top up fine? What sort of fluid should I use? I can't find much at our local parts store so I can either order from Rockauto or FCPeuro since I'm in Canada

rumb

Looks like the input seal for the driveshaft. Best to replace seal and then drain and fill.
'68 250S
'77 6.9 Euro
'91 300SE,
'98 SL500
'14 CLS550,
'16 AMG GTS
'21 E450 Cabrio

daantjie

Again, you need to thoroughly clean the whole diff properly before you do anything. The fluid will of course drip off the lowest point, but that does not mean that is the spot it is leaking from.

To check level, you need to remove the fill plug.  The diff is properly filled if a little stream of oil comes dribbling out of the fill plug hole.  Castrol Syntec 75W-90 is a good all round diff oil to use.  So to fill you keep squirting fluid into the hole until a little bit comes out.  OK that sounded a tad dirty, but you get the picture:)
Daniel
1977 450 SEL 6.9 - Astralsilber

carzilike

I went to my local shop today and they checked the diff fluid level. It was about half. They topped up with 0.5L of fluid. I will monitor how the leak is. They suggested in the pinion seal that is leaking
I am wondering if in order to get to that pinion seal will Differential Output Seal will come out?

If yes then should I just order both and have both replaced? The seals are not expensive but I assume the labor will be...
Also how many hours of labor should it be in order to replace one or both seals (roughly if nothing is seized etc)