SL-Class (R129) 1990-2002: SL 280, SL 300, SL 320, SL 500, SL 600, SL 60 AMG

SL/R129: Transmission Dipstick - bought one, does not fit

Old Aug 28, 2024 | 08:55 PM
  #1  
Eiderdown's Avatar
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From: Colorado Springs, CO
1997 SL320, 1972 TR6, and 1981 Euro 230CE
Transmission Dipstick - bought one, does not fit

My recently acquired 1997 SL320 has an issue when cold...does not want to upshift from 1st to 2nd or 2nd to 3rd. This goes away after driving a few blocks. It seemed like a wise idea to check the fluid level in the transmission but...no dipstick.

The VIN decode tells me it is a 5-speed auto tranny which I thought meant that it was a 722.6 transmission and I ordered a dipstick off eBay. Unfortunately, when I try inserting it there is 12 inches or more still sticking out when it stops and won't go any further. Upon removal I see that the measuring end is covered in tranny fluid. Not quite sure what to think...the seller has not responded to my inquiry although he lists it as "compatible".

Any thoughts? How do I confirm the transmission model number?
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Old Aug 29, 2024 | 07:32 AM
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bttucker's Avatar
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From: Columbia, MO
2001 SL500, 2017 GLE350
You must learn to feel when the dipstick hits the bottom of the pan. Then mark the dipstick where it sticks out, for easy insertion when measuring. My presumption is that there are many different lengths of trans fill tubes. Don't forget to order the red tube seal - here's what I bought on Amazon:
Dorman 917-299 Transmission Filler Cap Lock Pin Compatible with Select Dodge / Freightliner / Mercedes-Benz Models, 5 Pack Dorman 917-299 Transmission Filler Cap Lock Pin Compatible with Select Dodge / Freightliner / Mercedes-Benz Models, 5 Pack

Last edited by bttucker; Aug 29, 2024 at 07:33 AM.
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Old Aug 29, 2024 | 10:22 AM
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Eiderdown's Avatar
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From: Colorado Springs, CO
1997 SL320, 1972 TR6, and 1981 Euro 230CE
Well, I guess that is one approach. I just assumed it would fit like a normal dipstick...go all the way in, seal the tube, and just stay there.

How do you know that "touching the bottom of the pan" is providing an accurate measure? The one I bought is approx 48" long: https://www.ebay.com/itm/353602457872
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Old Aug 29, 2024 | 11:14 AM
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From: Columbia, MO
2001 SL500, 2017 GLE350
Feel free to research as I did and post any other results. What other 'indexing' could one possibly achieve with this tool? Mine has a plastic tip with temperature range markings on it - does yours?
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Old Aug 29, 2024 | 12:24 PM
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Eiderdown's Avatar
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From: Colorado Springs, CO
1997 SL320, 1972 TR6, and 1981 Euro 230CE
Mine does have the plastic tip with temperature markings. What I'm questioning is that at 25deg C, and the tip of the dipstick touching the bottom of the pan, there would only be just under an inch of fluid in the pan. That doesn't seem like very much to be "full". But perhaps it is.



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Old Aug 29, 2024 | 05:25 PM
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SL600
Measuring at 80°C is recommended. Engine must running.
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Old Aug 29, 2024 | 10:35 PM
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From: Colorado Springs, CO
1997 SL320, 1972 TR6, and 1981 Euro 230CE
Originally Posted by bttucker
You must learn to feel when the dipstick hits the bottom of the pan. Then mark the dipstick where it sticks out, for easy insertion when measuring. My presumption is that there are many different lengths of trans fill tubes.
Found an OEM dipstick and it had this note with it:
Use: (Qty.) (1) 140-991-00-55.; For Filler Cap Lock Pin; This Tool may be longer than the Dipstick Tube, if so, insert it until it bottoms out, and check the fluid level; Use and remove, do not leave in the vehicle

So...I guess that's the story. I'll be sure to check this again with the engine hot, idling in park.
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