1987 W124 230E (M102 engine) 190,000 km (105,000 miles)

Hi all,

This is my first post with a query. I'd like to say what a great resource this site is, and I've learnt much from members' experiences, problems and solutions. I'm doing more and more work on my car, and enjoying the break from the desk job.

Now to my problem. Following my Haynes manual recommendation for 36,000 mile service, I drained the transmission and torque converter, changed the ATF and filter, replaced the gasket with a dealer one, and tightened pan bolts to 8 NM.

Positives: I've never done this job before. The car was shifting fine, and shifts even nicer now. The fluid was still red but had a brown tone to it, and the filter was dirty, so glad to have done this service job.

But woe is me: there were no leaks before, and there is now a gasket leak. I noticed some corrosion on a small area of the outer lip of the pan, but it didn't affect the mating surface where the pan rim meets the gasket. It looks like the gasket slipped very slightly at the corroded area on reinstallation and now ATF is dripping from there.

I thought that 8 nm torque on the pan bolts may not be enough, so I've tightened it to 10. Slowed the drip, but it's still there.

The questions: maybe tightening the pan bolts will work? What's the maximum torque you've ever applied to the transmission pan bolts? And, it looks like I may need to drain the tranny and check the gasket. Sob. Is it OK to save the new ATF and re-fill the tranny with it when I've checked the gasket? Or are there risks?

Is there anything else to look out for/be aware of? Please help, the wife needs the car and I'm in the "there was no leak before and you've 'fixed' it and now there's a leak" dog box -- when preventative maintenance goes bad.

Cheers
John

I have the same troubles. The gasket and pan seem to be tempermental on the reinstallation. The old pans lip was bent from overtightening so I was told. I bought a new pan and installe dit and new gasket. No leak afterwards for a few months, now leak is back. I think there is a trick to tightening the bolts ...not too little, not too much and the gasket and pan must sit just right. Seems hard to get it right without car on lift for a good look see what you are doing. My 190e 16v has sealed fine and leaked at the pan 3 different times. This last time even with a new gasket and pan. The second time the leak was there, the overtightend bolts had cut the gasket in two along one side of the pan. Definitely possible to overtighten and cause the leak. Be carful

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Christopher Henkel
1990 190E 2.6 - Arctic white SOLD
1986 190E-16v - Blauswartze
1993 300CE - SOLD
2003 W208 CLK 320 Cabriolet - Magma Red

Mines leaking too, but it's been on awhile and likely needs changing.

These things are sensitive to over-tightening.

I'll throw in my 2 cents.

I have never had any luck with the pan gasket sold by internet service providers.

To solve this problem, I've used dealer purchased pan gasket and filter. I realize the filter has nothing to do with the leak, but for me it would make no sense to buy one part here and another part there.

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Mike Murrell
1991 300-SEL - Model 126
M103 - SOHC
"Fräulein"

Mike and Christopher, good to hear I'm not alone. It's a pretty cramped job, even on 4 x jack stands. I used an OEM filter and gasket so no materials issues. I've just been out and drained the tranny, removed the pan and checked everything. I think I've found the problem -- the bolt by the leak is partly cross-threaded, and it has distorted the pan a little which in turn has affected the gasket mating surface and caused the leak. I didn't think I was using excessive force -- far from it -- but must have done so. And looking at the picture of the new AT pan on Fastlane I can see that many of the bolting areas on my old pan were bent out of shape by previous owners before I had a go at this job. Happy 20th birthday, car.

So,a new pan coming right up. I think I'll also need to tap a new thread and fit a larger bolt, which I'm a bit nervous about doing around the transmission (cleanliness v. metal shavings). I'll keep you posted. Fixing and servicing this car is like playing dominoes. Still, better dominoes than roulette.
John

SOunds lik eyou might have it figured out. I am definitely tired of the leak when you do a ATF change. Last time it started to leak it was over tightening for sure on my part and the pan was out of shape. Easy to do. Bought a new pan and gasket. pan was OEM but gasket was internet who ever. A few months later I got a leak again. Not happy, dont think it was overtightening, maybe materials. Guess I get to crawl under the jack stands again and get an OEM gasket too.

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Christopher Henkel
1990 190E 2.6 - Arctic white SOLD
1986 190E-16v - Blauswartze
1993 300CE - SOLD
2003 W208 CLK 320 Cabriolet - Magma Red

Yes, the metal is quite thin. I'm in New Zealand and there are no new pans available in the 'obsolete parts' warehouse. The dealer has had to order one in from the Asia Pacific distribution centre in ... Singapore. We discussed the merits of fitting a secondhand one from a wrecker, but it's likely that it may have similar issues given the car's age; I don't want to fit, refill and discover another leak. False economy, and my driveway is getting sick of drinking ATF!
John

I haven't done this to a MB tranny pan but it is possible to reuse the pan. The usual distortion caused by overtightening is a 'dimpling' or depression of the metal around the hole. By turning the pan over and carefully hammering the 'dimple' flat, the pan can be reused.

This leak trouble makes me think that I'll just do a flush through the transmission oil cooler lines as I do with my Volvo. This changes all the oil but not the filter. It is very easy to do, you need not even change clothes!

Has anyone been changing their tranny oil by this method? What was your experience?

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1986 300E
1993 Volvo 940 Wagon
1984 Volvo 240 (daughter's)
1976 Dodge 1/2T pickup, gas hog

I've gotten into the habit of checking the flatness of the pan mating surface with a straight edge every time I drop the pan. It shouldn't be difficult to straighten out a pan on the bench with a hammer backed by wood or metal.

I too use the cooler line method of changing transmission fluid on my cars... but not on my MB, because it has a drain on the torque converter, which allows me to drain >80% of the fluid in the transmission unit.

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95 E320 Cabriolet, 159K

Thanks for the advice about checking with a straight edge as a matter of course, and using a hammer and wooden block. Would have saved me a lot of hassle.

I received the new transmission pan from Singapore within 48 hours of the dealer putting the order through. Pulled the old one. It was instructive seeing old and new side by side – the new was perfectly shaped to the transmission, and the gasket sat perfectly. The old pan was really out of shape and several of the curved bolting areas were almost flattened. Not surprising I couldn’t get it to re-seal, even with a new gasket. Someone had already done the hammer trick on it. At least once! And with a bit of corrosion as well, new pan was warranted.

Offered new pan with gasket up, and progressively tightened the 6 bolts from hand tight through 2, 4, 6 and finishing at 8nm. It has been on for nearly 2 weeks now, and not a drop of ATF to be seen where it shouldn't be.


Before servicing the car had a problem, which has continued. It shakes when drive is engaged and when stopped at lights etc. The shake feels like a clutch slipping in a manual, but it's an auto. Can feel a bit of vibration in steering wheel and driver’s seat when driving at 50--60mph (3000 rpm). Still have the problem, and it varies in intensity from barely noticeable to 'change, light, go green now, get me moving again!'

Car starts easily. Engine idles smoothly and consistently in park and neutral. Reverse engages smoothly. and quickly, and drive engages quickly. Shifts smoothly when rolling, engine runs smoothly.

I’ve done some searches here and they led me to the engine mounts. Have inspected them and the rubber is cracked. Really cracked. Will install replacements over the weekend. One mount is accessible, the other (passenger side in my right hand drive) looks impossible to get at, but everyone says to persist. I won't start a new thread with this issue as there's plenty written already. I hope it's the mounts, not the transmission ...

John