Auto gearbox gears slipping badly

[Mohan58]

Hi guys,

My auto gearbox in my 250SL started slipping to a point the car won’t move off quickly. If I accelerate she slips badly & I get the smell of auto fluid. I tried popping it in reverse & it seems like it’s stuck in one of the forward gears too. After pushing the car back into the garage, I notice a lot of ATF oil on the road. It struggled to move.

Tried looking for the dip stick to check levels, can’t seem to find it. Mine 250SL is a 1967 September manufacture. Is there a gearbox manual?

Any suggestions as to what I should look for? Are there reconditioned gearboxes for sale or new ones? Whats the cost?

Thanks & stay safe.

[MartinK]

Hei. Bad Story. First of all you have to search for the leaking reason. Fill the transmission with ATF type A Suffix A or Dexron IID. Do not try to start the engine without fluids in the transmission. When the engine is turned off, fill maximum 2cm above the max-level of the dipstick and try to fire the car up and check immediately if oil gets out of the transmission. In the manual it is mentioned and explained how to check the fluid level. Most problems are only to solve if the transmission is out of the car but maybe you can fix the leakage. For a repair I can only recommend workshops in Germany. Good luck.

[Mohan58]

Thanks Martin. Will try this.
 Unfortunately i am finding trouble locating the dipstick for the gearbox.

Cheers

[Cees Klumper]

It should be on the passenger side, closer to the firewall, relatively visible compared to some more modern cars I have had. There's a sort of 'hat' / cap on top of the dipstick that protects the filler tube from stuff getting in.

I just checked mine last weekend as, in fast corners, the box downshifted when it would never do this before. The fluid level was about 500 ml low, I filled it to closer to the max mark, and the shifting is back to how it was, smooth, no more downshifting in corners. The box does leak just a little bit, which I need to chase down. This was the first time I had to top up since changing the fluid and filter back in 2002.

[MartinK]

Here is the dipstick located. Talk soon. Martin

[Mohan58]

Thanks Cess.

[Mohan58]

Thanks for the picture. Perfect.

[MikeSimon]

You may already have damaged your transmission quite a bit. Low fluid levels will cause the clutch packs to slip. That is the effect of what you experience, together with the smell of burned fluid.
Do not drive the car without making sure your oil level is proper. Check the procedure in the owner's manual. The engine may have to run.

[MartinK]

Hei, yes Indeed. Driving a few hundred meters or a few minutes with a slipping transmission could cause a fatal Crash.

[Shvegel]

Another thing to check or have checked is the three position solenoid. Accessible through an oval cover under the carpet on the right side of the transmission tunnel it controls the control pressure of the transmission.  Of of it’s positions drops pressure to reduce load on the engine at idle.  If it is stuck there it will do what you describe.  Much has been written about this here so search “3 position solenoid” try searching that.

[Mohan58]

Thanks so much. Will look into this.
Cheers

[WRe]

Hi,
I don't want alarm you but when your transmission already slipped the likelyhood of burned clutch coverings is high because they are very thin only coated like paint. See https://www.sls-hh-shop.de/main/en/mercedes-230-280sl-w113-/27-automatic-gearbox/27-i-info-belagzustand.
You should check your oil (on the dipstick, better oil change) for colour (dark red or burned brown) and for smell (oily or burned).
...WRe

[MartinK]

Another thing to check or have checked is the three position solenoid. Accessible through an oval cover under the carpet on the right side of the transmission tunnel it controls the control pressure of the transmission.  Of of it’s positions drops pressure to reduce load on the engine at idle.  If it is stuck there it will do what you describe.  Much has been written about this here so search “3 position solenoid” try searching that.

That is right but if the three position solenoid has no DC voltage, it remains always in "drive" position. The transmission should work but you have no kickdown and while slow down and self shifting in slow gear the transmission makes noise and it feels very hard shifting. The possibility that the selenoid is seized in idle position is not impossible but not expectable. But it is no mistake to check. For correct adjustments you need a pressure gauge.

[Shvegel]

You are correct that without power the arm should settle in the center or drive position.  It is actually quite common for the linkage of the solenoid to stick in either kickdown or idle position especially if the car has been sitting. It happened on my car twice in the kickdown position leading to higher than normal and harsher shifting.  When I restored my car I replated the linkage and greased it with some teflon based space grease given to me years ago by a former customer who was a fluid engineer.  Hopefully the Teflon will keep water out of the works.

[MartinK]

Thanks for your reply. To avoid a seized linkage of the three position solenoid just put grease into the ball joints and do not forget to put the sealing washer 0009976041 (pos. 32) between ball and linkage. So you avoid water and moisture in the ball joints.

The support (pos 18) is possible to remove and open and clean while the transmission is in the car. Difficult but it works.

Talk soon,  Martin.

[Shvegel]

Martin,
I have never seen nor heard of the sealing washer before.  Thanks for that.

[ja17]

Lubricate the linkage ends and pivots at each end.

[Mohan58]

Thanks everyone for your kind help. Found out today that my part of my radiator is also the oil cooler. The two hose that go into the it broke due to age.

Another thing we found out is that we cant find the dipstick for the gearbox. Totally baffling me & my workshop.

Appreciate all the help & advise from all of you.

Take care & stay safe.
Cheers