Automatic transmission questions?

[Ed Riefstahl]

Greetings,

I'm looking for some feedback from the transmission experts. Are there any issues that can cause sudden catastrophic failure with these 4 speed automatic transmissions in the 66 230SL that I'm not aware of?

Other than the fact that it takes a few seconds after cold start to build up proper pressure, the transmission shifts fine with no other issues. I do plan to do a fluid and filter change this spring, including draining the torque converter.

The reason I'm asking is, my wife and I are considering another long road trip, possibly even to Canyon Lands / Pikes Peak etc. this summer for our 47th anniversary.

I now have the differential back in the car in top condition with all new rubber mounts and solid boot. I also completely rebuilt the brake system front to back, as well as hub bearings, seals etc. Even new motor mounts. Booster was new a few years ago. 

Last summer my wife and I also went completely through the cooling system including radiator and water pump. Also new alternator, Power steering, starter motor, also belts, hoses etc while we were in there. U-joints are recent too.

The obvious reason for asking these questions regarding the transmission is because of recent catastrophic differential failure. We have driven our Ms Magoo 65,000 miles, coast to coast and Maine to Florida over the past 21 years with only a leaky fuel hose once and one flat tire.

We have maintained her to the max, plus its mechanic goes along with her on all the adventures. We do understand that anything can fail, but that differential failure last fall was a real shock. So glad we were only 15 miles from home. Utah is 2500 miles.

Thanks in advance for any comments.
Ed Riefstahl
Erie, PA

1966 230SL (Ms Magoo)
1970 280S (Miss Daisy)
1989 300SE (Majestic)
1999 BMW Z3 5 speed
1991 BMW 318I 5 Speed
1997 Toyota Paseo Convertible - Red 5 speed (have you ever seen one?)
1997 Ford Ranger Step Side 55K
2023 Mazda CX 5

[ja17]

Yes service it. Sudden catastrophic  failures are unusual. While you have the transmission pan off, torque the valve body bolts since they can become loose. If your lucky your cold temperature problem will be fixed in the process.

[WRe]

Hi,
the K4A025 automatic transmission is actually considered to be very robust. What is needed, however, is the right (ATF type A suffix A) sufficient and clean oil. If this is not the case, it can be damaged very easily.
The workshop manual contains possible errors and their causes.
E.g. if 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 can check your oil (on the dipstick, better oil change) for colour (dark red or burned brown) and for smell (oily or burned).
...WRe

[Ed Riefstahl]

Hi guys,
Very good comments. Yes Dextron type A is always the best for these. Without looking it up, I think this will be 4th fluid change in 21 years / 65,000 miles.

However I've never touched the valve body on any of my 113's or 108's in the 45 years I've owned, driven and repaired these cars. Never had a reason to or ever thought to check the bolts - very good advice Joe. I will definitely do that.

This list is so great. Sure wish I'd have found it years ago. I was part of another MB list for over 20 years and was kicked off a year ago. It got to the point most folks on that list drove new MB's and didn't like old school folks that think outside the box, if you will. Enough said.

I must admit, I'm a little more nervous at the thought of taking a 57 year old car on a 5000 mile road trip this time. Last extensive trip in Magoo was 2014 from PA to CA to cross the Golden Gate Bridge. Traveled 7000 miles (all back roads) in a little over 3 weeks.

Now that my wife's cancer is behind us and near 100% 10 year survival rate, we are really anticipating another road trip in Ms Magoo. Not sure where, but lots to see in the great USA. Trying my best to make sure all three of us are up to it.

Thanks for comments and suggestions.
Ed Riefstahl
Erie, PA

1966 230SL (Ms Magoo)
1970 280S (Miss Daisy)
1989 300SE (Majestic)
1999 BMW Z3 5 speed
1991 BMW 318I 5 Speed
1997 Toyota Paseo Convertible - Red 5 speed (have you ever seen one?)
1997 Ford Ranger Step Side 54K
2023 Mazda CX 5

[MikeSimon]

The weak part in any conventional auto tranny are the clutch packs/bands that control the planetary gears. If the oil level is low or the wrong oil is sued, they wear and then shifting if off or not at all there. Proper maintenance will prevent that. But then again, like with any friction part, they don't last forever.

[stickandrudderman]

I had one once where it would sudenly lose drive after 45 minutes of driving. I replaced the valve body and it was cured but I couldn't see any obvious defect in the old one.

[Ed Riefstahl]

Thanks for the comments and suggestions guys,

I do recall an issue we had about 12 years ago where the car would down shift really hard when coming to a complete stop. It turned out to be the actuator (relief valve) that is mounted high on the passenger side of the transmission, out of reach from the bottom side. Not sure of the correct name, but it releases the hydraulic pressure when the car down shifts.

I had to pull back the carpet to find and remove the access panel. Sure enough the linkage was frozen and needed cleaned and lubed. What a difference it made in the shifting of the transmission after that.

Ed Riefstahl
Erie, PA

1966 230SL (Ms Magoo)
1970 280S (Miss Daisy)
1989 300SE (Majestic)
1999 BMW Z3 5 speed
1991 BMW 318I 5 Speed
1997 Toyota Paseo Convertible - Red 5 speed (have you ever seen one?)
1997 Ford Ranger Step Side 54K
2023 Mazda CX 5

[ja17]

I think you are referring to the three position solenoid. It's linkage moves a lever which lowers the modulator pressure in the transmission. Improper engine linkage adjustment can also cause it not to work correctly.

[ctaylor738]

Good news about the wife! 

More likely to fail are the bushings in the shift linkage, especially in a car that's been off the road for a while and is starting to be driven.

Cheers.

CT

[Ed Riefstahl]

Hi CT,
You're not kidding about the plastic bushing on the shift linkage. I had forgotten about that one. We had that fail a couple years ago while on a weekend road trip near Columbus, Ohio. The bushing just fell completely off and so did linkage.

Had my tool box with me and was able to remove the shifter from the top side and reach in the tunnel and put the car into gear to drive it.

Drove to a near by NAPA with shifter in hand and the guy took the shifter in the back and drilled a small hole in the peg and handed it back to me with a cotter pin and washer. It worked like a charm to get me home. At home I ended up making a brass bushing and used a cotter pin and washer to permanently repair it, even though I do had new nylon bushings. It will never fall off again, I assure you.

I also replaced the bushing on my 108 last summer. On the 108 the linkage can't fall completely off like the 113. Some times it's the simplest little thing that can let you down.

Thanks for the comments,

Ed Riefstahl
Erie, Pa