[R129 SL] '98 SL500 Oil Leak

[MBKindOfGuy]

Thanks Peter.  I'm going to crawl under my SL this coming weekend and check it all out.  From what I can see on the car now, and from the service manual, this appears to be one Benz where you can drop the oil pan rather easily to replace the gasket.  If that's what needs fixing, then I'll take care of it.  

On the oil capacity, I thought that 8.5 quarts sounded high too, but I looked again at the owners manual and the service literature, and both specify 8.5 quarts with an oil filter change.  So to be over-filled, there would have had to be some oil left in the sump when I extracted it through the dipstick tube.  I'll see if that happens this time by simply removing the drain plug after the extraction through the dipstick tube.  If there is any left in the sump, it will come out of the drain plug.  I've been doing this extraction method for years on other MB's (which many MB dealers do as well).  As I mentioned, never a drop came out of the drain plug afterwards, but I have yet to try that on this SL, and will this time.  In any event, the dip stick itself surely does not show an overfill.  

I don't really know for sure, but will report back on what I find as the source of the leak.  Being an Engineer, I won't stop searching until I find that :)

Regards,
Howard M. Ginsberg
1998 SL500, 59KMiles
1993 300E, 126KMiles
1988 300E, Sold at 165KMiles
1986 300E, Sold at 180KMiles


  ----- Original Message ----- 
  From: Peter Shelton 
  To: SL Mailing List 
  Sent: Tuesday, January 02, 2007 9:50 PM
  Subject: Re: [R129 SL] '98 SL500 Oil Leak


  Hi Howard,

  I am new to R129's but not to Mercedes Benz Cars, and live in New Zealand.  I have recently bought a 1992, R129 with 48,000 kms (genuine) on the clock, and I noticed the car had virtually every seal replaced from the rocker seals to the oil pan and all in between.  I obtained a copy of the original invoice from the MB repair shop and was told that cars have to be used or the oil and water seals will fail.  It is apparently predominant on many earlier MB V8 engines and the vehicles like longer trips - need to get nice and warm.  On the invoice was also a new water pump and seal.  Apparently the car had travelled some 5,000 km in the past 4 years and a few things had seized up and replaced.   

  Also the rams on the rag top roof were replaced as the car had been sitting (oil gushed all over my jeans when I was testing the car before purchase). Even the seals on the power steering pump were recently done ( all this work in the last 5 months).   

  We also have a 1974, SL 350 (R107) and have had no similar problems - but this car is used for long trips only (400 km plus at a time).  I know of others who have virtually replaced every seal in the 350 V8 engine. 

  I also noticed that you put in 8.5 quarts of oil!!   This seems a bit high as I understand that the R129 takes approximately 8 litres of oil (and 8.5 quarts is about 10.2 litres) .  On calculating this is about 3 pints too much. This could be the source of the problem. 

  I also ride Harley Davidson motorcycles (1340 cc) and over-filling the crankcase causes a trail of oil all over the right side of the engine (and all over my leathers).  The bike just spits it out of the overflow!  

  Above not perhaps too useful, but all I can recommend is ensuring the correct amount of oil is in the sump/ engine, and if all fails, all the engine seals, oil pump, etc be checked when the car is hot, and replaced as appropriate.   Taking the car on a good run will certainly locate the source of the problem(s).  

  For further information, we also have two W123's - a 250 and a 280E (and a further 250 for parts) and a W201- 2L (and a further one for parts).  Good luck with your challenge, 

  Kind Regards from New Zealand,

  Peter Shelton
  (alias Benzcruiser)

  ----- Original Message ----- 
    From: MBKindOfGuy 
    To: SL Mailing List 
    Sent: Wednesday, January 03, 2007 2:58 PM
    Subject: Re: [R129 SL] '98 SL500 Oil Leak


    Thanks for the response George.  

    I thought about those o-rings too.  I've only done one oil change on this SL since we've owned it and don't recall if I used two o-rings or not.  I just can't remember, but I am generally pretty good about replacing all the parts like this during oil changes.  I too will lower the dust cover (also reduces road noise) and take a closer look.  The car was "dry" for about 6 months, and the leaking oil started to appear shortly after I did that oil change, so it could all be related.  I do check the level and it's perhaps 1/8" from the max mark on the dip-stick.  I don't know if I overfilled the sump during that change.  I did put in 8.5 quarts with a new filter.  

    I use a topsider to suck out the old oil, but perhaps there was some left in the sump when I added the new oil.  I've used the topsider on several other MB's, though, and have tested many times to see if any oil remained after sucking it out the dipstick tube by pulling the drain plug.  Hadn't ever had even a single drop come out, but none of those oil changes were on an SL.  So this time I'll suck it out the dipstick tube, then remove the drain plug and see if any remains.  Will report back what I find, when I find the cause!

    Regards,
    Howard M. Ginsberg
    1998 SL500, 59KMiles
    1993 300E, 126KMiles
    1988 300E, Sold at 165KMiles
    1986 300E, Sold at 180KMiles


      ----- Original Message ----- 
      From: George Jenner 
      To: SL Mailing List 
      Sent: Tuesday, January 02, 2007 7:48 PM
      Subject: Re: [R129 SL] '98 SL500 Oil Leak


      Howard, I too have been experiencing a small amount of oil leaking.  The leak I have seems to be coming from the oil filter cartridge housing cover which is located on the right side.  There are two O ring type seals on the cover and I changed these recently but I have not had a chance to remove the dust cover under the engine to clean it so I can see if the new O rings have helped.  When I got a new oil filter from MB there was a package with the O rings and new washers in the carton, but the last filter I got from NAPA did not have these with it so from now on I will get my new oil filters from MB.

      Hope you find that leak and let us know where it was - George Jenner  1996 SL500  80K
        ----- Original Message ----- 
        From: MBKindOfGuy 
        To: R129 List 
        Sent: Tuesday, January 02, 2007 6:55 PM
        Subject: [R129 SL] '98 SL500 Oil Leak


        Good to be back on the R129 list.  

        I've noticed some oil leaking on our 129.  Will put the car up to take a very close look this weekend.  Did take a peek at the oil pan as best I could.  Looks like oil leaking on rear of pan seam or perhaps coming down from somewhere above to that area.  It's enough of a leak that I've got newspaper under the car and could see about 3 or 4 drops a day getting on it.

        Saw a website where someone had a leak around the oil level sensor electrical connection, but this seems to be dry on my car.

        Are the oil pan gaskets a common problem area on these cars, or are there other comments on common causes of oil leaks on this chassis/engine?

        Regards,
        Howard M. Ginsberg
        1998 SL500, 59KMiles
        1993 300E, 126KMiles
        1988 300E, Sold at 165KMiles
        1986 300E, Sold at 180KMiles
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