I drove Highway 50 a few days ago in my '82 300sd and was thinking about differential longevity. My car has 340,000 miles, original motor, replacement trans, and diff is still factory. This car has a history of consistent maintenance -do diffs ever really die? I think I will replace fluid next week with Mobile 1 80/90 synthetic as it has been about three years since I last changed diff oil -

Mine is original at 500K miles, I recently had the fluid changes. I think they normally last awhile.

Usually a differential will outlast the car. I've never had one go bad except as a result of oil loss.

yea, it does seem like they outlast a car in most cases - mostly just curious to see what kind of life most 126/123 owners are getting from their diffs

yea, it does seem like they outlast a car in most cases - mostly just curious to see what kind of life most 126/123 owners are getting from their diffs

Differentials are long lived. they do seem to get neglected by the majority of people.
Mine is the original with 357,000 on it.

I did start to pull one out of an 85SD a couple yrs ago. When I got it opened up, there were some edges on the gears chipped and pretty sparkly stuff in the oil. Dang and it was a 2:88 too.`

Charlie

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there were three HP ratings on the OM616...

1) Not much power
2) Even less power
3) Not nearly enough power!! 240D w/auto

Anyone that thinks a 240D is slow drives too fast.

80 240D Naturally Exasperated, 4-Spd 388k DD 150mph spedo 3:58 Diff

We are advised to NOT judge ALL Muslims by the actions of a few lunatics, but we are encouraged to judge ALL gun owners by the actions of a few lunatics. Funny how that works

My old 300d did 800kmiles with diff oil changes every 100k or so, it developed a slight whine at about 600k after being drowned. The oil was white when I changed it. They sometimes ware a little in the spider gears if they do a lot of cornering under load. The old one has a bit of backlash, to be expected at that mileage. Unless you are abusing your diff, they go for ever.

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Grumpy Old Diesel Owners Club group

I no longer question authority, I annoy authority. More effect, less effort....

1967 230-6 auto parts car. rust bucket.
1980 300D now parts car 800k miles
1984 300D 500k miles
1987 250td 160k miles English import
2001 jeep turbo diesel 130k miles
1998 jeep tdi ~ followed me home. Needs a turbo.
1968 Ford F750 truck. 6-354 diesel conversion.
Other toys ~J.D.,Cat & GM ~ mainly earth moving

My dad's '83 SD had a neglected (by prev owners) differential, it was clunking and dumping metal shavings into the oil at 304k.....and with that much play in it we decided to swap it out. In its place is a 2.47 diff with 334k on it....runs smooth and no wear on the gears!

My car is at 287k on the original diff....runs quiet and smooth. I change the gear oil with synthetic every couple of years.

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-diesel is not just a fuel, its a way of life-
'15 GLK250 Bluetec 118k - mine - (OC-123,800)
'17 Metris(VITO!) - 37k - wifes (OC-41k)
'09 Sprinter 3500 Winnebago View - 62k (OC - 67k)
'13 ML350 Bluetec - 95k - dad's (OC-98k)
'01 SL500 - 103k(km) - dad's (OC-110,000km)
'16 E400 4matic Sedan - 148k - Brothers (OC-155k)

Just cracked open my differential and everything looked mint as far as I could tell.

85 300D at 340,000 I figure I can sell the whole thing for 200-300$ when my car ends its long life.

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-Typos courtesy of my mobile phone.

Interesting. I didn't know they were so robust. I can remember a real estate agent who put about 75k miles per year on his car having one that whined and a slight clunk evertime he floored it (every time he accelerated in other words.) It was a 77 300D, and this was in about 1980. He seemed to think since it was a Mercedes, it would last forever.

I don't generally check them either. Seems like my Mercedes dealer used to check it when they did oil changes.

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1979 240D, 4spd manual, Power Sunroof, manual windows, 147k miles, Pastel gray/Black MB Tex.
1991 300D 2.5 - Smokes like it's on Crack!

Sure. The clunk could easily have been a bearing and the whine could easily have been gear deflection caused by the play from the bearing. Neither of those things are terminal for a differential. Even a chipped tooth here or there doesn't sound the death knell.

Shockload, lube starve/contamination, traction devices, high torque/hp and oversized tires are what typically do in differentials. More drag racer/4wd type problem than a stock MBZ problem. Lesser stock vehicles typically see diffs last their entire service life. I fail to see why a mercedes would do any worse.

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'84 300D
'97 Jeep XJ lots of mods
'01 Subaru Forester

They should last damn near forever.

You have to figure MB built the W126's driveline to take near 300hp in full blown Euro form. The diesel isn't stressing anything at all.

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1999 SL500
1969 280SE
2023 Ram 1500
2007 Tiara 3200

I don't know about the older models, but in the W210, the V-8 gets larger differential gears than the diesels or small gassers.

There have been some nasty looking pictures on here of worn out differentials. My 85TD has a whine/grind noise in it at certain speeds. This reminds me that I need to change out the gear oil. When I took it to an indy to diagnose a thumping which turned out to be dry CV joints, he detected the whine/grind and said it was indicative of a worn differential with which he seemed quite familiar so they aren't completely bombproof.

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1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13

On the older ones MB just changed the ratio, they all used the same differential. I think the 560's were like 2.47 and the diesel 3.07. Something like that.

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1999 SL500
1969 280SE
2023 Ram 1500
2007 Tiara 3200