'99 Sl 500 Transmission Problem - PeachParts Mercedes-Benz Forum

Cmwhite303 · #1 02-03-2006, 01:20 PM

Just found out from MB service technician that my transmission is destroyed and a new one plus catalytic converter will run $6750. I had an A service last week, and the car seemed to run beautifully after. Two days later, while stopped at a light I felt a thump somewhere in the rear end. Thinking the guy behind had bumped me I got out and looked but didn't see any scratches. Drove another 1/4 mile, felt it again, then the car sharply decelerated and stopped. Discovered that everything from Park to 1st was gone. Eventually got Drive to work a little by applying excess throttle, and drove 3 miles to the MB dealer. The technician said he was familiar with this type of problem...mentioned oil getting into a harness and control module, wrong signals being sent to the tranny and total destruction of the tranny. Yesterday, he confirmed that my tranny's completely gone.

I'm now trying to assess my position. Bought the car 8 months ago with 75K miles (now 85K) for 10 grand below blue book. Didn't get mechanical breakdown insurance because of the cost and I've been lucky with cars until now. Considering my large down payment, I feel I'm in too deep to let the car go. Except for the tranny problem, the car looks and runs beautifully (ha ha). Thinking about asking MB to help with the repair bill. The car's been well maintained and for the tranny to go out with no pre-warning or anything is unbelievable to me and reflects poorly on MB. Drove an Accord to 290K and never had a power or drive train problem.

Guess I'm worried that after getting this fixed, I'll possibly be looking at other expensive repairs as the car approaches 100K. Thanks for any ideas or comments anyone might have? Sorry for the long message.

page62 · #2 02-03-2006, 02:50 PM

I think they're trying to sell you a new tranny. Did you already authorize the work? If not, there are alternatives from rebuilt units to a unit pulled from a salvaged car. And don't be afraid to patronize independent mechanics (especially if you can get a recommendation).

However, I'm no expert. If you don't get anymore help here, jump over to the tech help forum. There are some really knowledgeable folks over there.

Cmwhite303 · #3 02-03-2006, 03:16 PM

Haven't authorized the work yet. Thanks for the advice.

jjrodger · #4 02-03-2006, 03:30 PM

Like you, I have a 1999 SL500. I waste a lot of time on this site when I should be working and I have read a lot about problems with the transmission model we have.

The dealer's diagnosis sounds genuine; I have read similar descriptions on this site. Our cars have what is described as a 722.6 transmission. It appears that MB has had reliability problems with it, albeit my impression was that these were confined to early, 1996 or 1997 cars, maybe 1998s at the latest. If you do a search on "722.6 transmission" you will turn up a rich seam of material on the subject. Tellingly, MB now recommends a once-only fluid and filter change at 40k miles for this transmission and its successor the 722.9; this is something to do with removing bits of metal that breakdown during the running-in period.

It may be that MB will chip in with some good will, especially if the car has been timeously and properly serviced within the dealer network to MB specs. If you bought from a MB dealer, this will further increase your chances.

If not, you may wish to consider a rebuilt transmission or having the job done by an independent, although the labour element on a transmission change is not that much, actually.

Why do you need to change your cats? Has the transmission failure somehow polluted them? That said, I need to change mine, the monolith is rattling away, although my car is at 105k miles now. I have heard of failing cats causing catastrophic damage to the engine: the monolith fragments and is somehow "sucked" back up to the motor causing untold damage. The cats alone represent about $2,500 of your bill there...

As to other repairs, these cars are pretty robust if well-maintained. I worry about the hood mechansim going, that would be a real killer...

iwrock · #5 02-03-2006, 03:38 PM

I would strongly reccomend finding a good independent shop or a transmission shop that will work on your Mercedes. The guys here at my local trannie shop (had 3 of the rebuilt there), and they all work flawlessly. They are more cost effective to have it rebuilt by someone other than the dealer. I asked then about my 600, and they said that it would actually cost around 3200 including tax to rebuild.

Also, you make me think about the ASR problems. We had the limphome mode trigger, and it is exactly what you describe. Slow acceleration, combined with a low top speed.

iwrock · #6 02-03-2006, 03:40 PM

I would also like to say "Welcome to Mercedesshop.com". I hope you enjoy your stay, and I hope that we can provide you with the information you need to get back on the road.

Cmwhite303 · #7 02-03-2006, 07:08 PM

Thought I did a pretty careful search of MB forums before making the purchase, but somehow missed the discussions on the 722.6 problems. The service tech might have meant torque rather than catalytic converter. But, I'll be sure to take care of the 'cats' if needed. Will also check with a nearby (Pasadena, CA) independent shop, though the good ones in my area seem to charge only slightly less than the dealer. There goes my vacation, new HD TV and big chunk of savings this year. Thanks for the insight, advice and warm welcome.

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99 SL 500
96 E320

HitParader · #8 02-07-2006, 03:05 AM

If you are in SoCal and can make it out the the Valley (Tarzana), you may want to consult with Mr. MB Motors. I'm not sure he does transmissions, but it's by far the most honest and reliable shop I've ever found. See the long thread about this great shop in the "Good MB Shops" forum