Author Topic: Rear Differential oil level  (Read 3710 times)

getsmart

  • Full Member
  • Silver
  • ****
  • Australia, Victoria, Dromana
  • Posts: 315
Rear Differential oil level
« on: January 07, 2021, 21:26:26 »
Hi All,

The BB tells me that the oil quantity for 230sl rear diff is 2.5 litres.

When I drained mine it only contained 1 to 1.5 litres. Yes I did lift both axles to drain the oil from them. I bought my car as an unfinished project so have never had it running though the diff appears to be in good condition (little backlash).

My questions are

1. Has anyone re-filled their diff and if so did they put 2.5 litres in?
2. Or did you just refill it until it started running out of the filling point? (shown in attached photo)

The diff at times had been stored pointing upwards so I wonder if there is a position where they will leak like out of the top of the breather hole.

Rgds, Joe
Finding the red car
1964 230sl Restoration Project

Benz Dr.

  • Associate Member
  • Platinum
  • ******
  • Canada, ON, Port Lambton
  • Posts: 7220
  • Benz Dr.
Re: Rear Differential oil level
« Reply #1 on: January 07, 2021, 23:01:58 »
If you have the car raised and the axles are hanging down then you won't want to fill to the bottom of the fill hole. I stick my little finger in the fill hole and as long as I can feel fluid, it's full.
1966 230SL 5 speed, LSD, header pipes, 300SE distributor, ported, polished and balanced, AKA  ''The Red Rocket ''
Dan Caron's SL Barn

1970  3.5 Coupe
1961  190SL
1985   300CD  Turbo Coupe
1981  300SD
2013  GMC  Sierra
1965  230SL
1967 250SL
1970 280SL
1988 560SEC

ja17

  • Full Member
  • Platinum
  • ******
  • USA, OH, Blacklick
  • Posts: 7414
Re: Rear Differential oil level
« Reply #2 on: January 08, 2021, 00:25:57 »
You have a nice picture of the location of the rear end ratio for an early car (3/75)
Joe Alexander
Blacklick, Ohio
1969 Dark Olive 280SL
2002 ML55 AMG (tow vehicle)
2002 SLK32 AMG (350 hp)
1982 300TD Wagon turbo 4spd.
1963 404 Mercedes Unimog (Swedish Army)
1989 flu419 Mercedes Unimog (US Army)
1998 E430
1974 450SLC Rally
1965 220SE Finback

getsmart

  • Full Member
  • Silver
  • ****
  • Australia, Victoria, Dromana
  • Posts: 315
Re: Rear Differential oil level
« Reply #3 on: January 08, 2021, 00:42:14 »
Thanks Doc - my axle is removed so I'll take that as close to the car being raised. I'm curious though the low oil level. I'm guessing there's a level range that they operate fine at but should not be too low of over-filled. I might try about 1.5 litres and use your finger method and keep increasing from there in .5 litre increments up to 2.5.

If my finger gets stuck I'll call you for urgent assistance (mental note to keep the phone in my pocket)  :) ;)

If you have the car raised and the axles are hanging down then you won't want to fill to the bottom of the fill hole. I stick my little finger in the fill hole and as long as I can feel fluid, it's full.
Finding the red car
1964 230sl Restoration Project

getsmart

  • Full Member
  • Silver
  • ****
  • Australia, Victoria, Dromana
  • Posts: 315
Re: Rear Differential oil level
« Reply #4 on: January 08, 2021, 00:43:37 »
Thanks Joe, yes its the original axle in my March 1964 230lsl  :o

You have a nice picture of the location of the rear end ratio for an early car (3/75)
Finding the red car
1964 230sl Restoration Project

MarkCan

  • Full Member
  • Silver
  • ****
  • Canada, Ontario, Mississauga
  • Posts: 261
Re: Rear Differential oil level
« Reply #5 on: January 08, 2021, 03:33:19 »
I think that what Dan describe for you is the way of checking the diff oil level at service intervals. When you are filling it go slow and as soon the oil starts to come back out you are done. Put the plug back on and wipe it clean.

Benz Dr.

  • Associate Member
  • Platinum
  • ******
  • Canada, ON, Port Lambton
  • Posts: 7220
  • Benz Dr.
Re: Rear Differential oil level
« Reply #6 on: January 08, 2021, 04:21:37 »
I think that what Dan describe for you is the way of checking the diff oil level at service intervals. When you are filling it go slow and as soon the oil starts to come back out you are done. Put the plug back on and wipe it clean.

Only if the axle tubes are perfectly level. Otherwise, use your little finger method.
1966 230SL 5 speed, LSD, header pipes, 300SE distributor, ported, polished and balanced, AKA  ''The Red Rocket ''
Dan Caron's SL Barn

1970  3.5 Coupe
1961  190SL
1985   300CD  Turbo Coupe
1981  300SD
2013  GMC  Sierra
1965  230SL
1967 250SL
1970 280SL
1988 560SEC

ronwall83

  • Junior Level
  • USA, NE, Kearney
  • Posts: 8
Re: Rear Differential oil level
« Reply #7 on: November 15, 2024, 19:24:30 »
What size alan key does a person need for both the drain & fill plugs?  Old thread...so here's hoping.
RW
'66 230sl

dirkbalter

  • Full Member
  • Platinum
  • ******
  • USA, CA, Corona
  • Posts: 1480
Re: Rear Differential oil level
« Reply #8 on: November 15, 2024, 20:29:15 »
What size alan key does a person need for both the drain & fill plugs?  Old thread...so here's hoping.

14mm Hex
Dirk
66 230 SL
70 280 SEL
53 CHEVY 3100
18 C300 COUPE
05 HD FLSTNI

Bshaunessy

  • Full Member
  • Senior
  • ***
  • Canada, British Columbia, Invermere
  • Posts: 126
  • 1957 190 SL; 1970 280 SL; 1975 450 SL; 1971 300 SE
Re: Rear Differential oil level
« Reply #9 on: November 16, 2024, 13:20:43 »
14mm hex head: HINT: you will need to shorten a standard "L" shaped 14mm hex wrench as the spacing between differential and body is very tight.