Mercedes 5 speed auto tranny reliability issues..? - PeachParts Mercedes-Benz Forum

J Irwan · #1 09-07-2004, 11:42 PM

Hi All,

How long does an automatic transmission clutch last..?

My 5 speed automatic tranny been getting a mis-shift lately ..

From 4-5th there is 1-2 sec delay (in neutral) and then abruptly engaging on the 5th.
This happen when accelerating..

I talked to the local dealer service manager, and he mentioned that there is certain diagnose to run to determine if some "value" reading is still within the spec.
This "value" from what I have been told will tell whether the clutch pack is worn and need to be replaced...

I am curious if the auto tranny need some interval clucth service like manual tranny..? I have always under the impression that the auto-tranny normally last 200-300k..

This mis-shifting never happened to me before.

PS: I never track or drag my car.. and it currently has about 82k original miles

mbdoc · #2 09-08-2004, 08:17 AM

There have been 2 MB 5 speed auto transmissions here in the USA. The first one was the 722.3 modified with an overdrive unit. That was only used HERE in the 1990-98 M104 engine R129 SL's & the 1992-99 300SE/S320's W140 cars.

The later 722.6 5 speed came to the USA in 1996 in V-8/12 cars & then ALL MB's from 1997, of course many V-8 2004/05 models can get the new 722.9 7-speed auto trans.

The biggest downfall of the 722.6 trans in your C36 is the lack of recommended fluid changes! The most common failure on pre-99 models is the rear plantary. MB used a bushing then & now uses a needle-bearing as a replacement on all but the 4-cyl versions.
IF you want a long lasting trans then service it at least every 30-50K miles, life-time fluids are a LAUGH in the real world! Servicing the 722.6 should run $250 +- a few $$$
A well maintained auto trans SHOULD last 200K-300K miles! But many don't!

J Irwan · #3 09-08-2004, 08:52 AM

M.B.DOC thanks for the reply.

I had my tranny fluid changed at around 67k.

When I bought the car 4 years ago it has 48k miles on it.
So I never changed the tranny fluid until it reached 67k.

When you mentioned servicing 722.6 cost $250++
Are you referring to fixing the rear planetary gear (or upgrading from bushing to bearing)..?

I am told that they will need to diagnose the car and see if the adaptation value is still within limit.

I am just a little dissapointed with MB that my tranny will need a rebuild at 82K. (ps: I don't track or drag my car).

Regardz,

PHAEDRUS242 · #4 09-08-2004, 09:19 AM

Changing the fluid should be close to $250. MB'a equipped with the 722.6 transmissions require one specific synthetic trans fluid ($$$) and using anything else will caus ethe trans to fail prematurely. There are countless threads about the proper method to check the fluid level as well, which is temperature dependent and must be performed with precision. The only proper way is to use the SDS tester the dealers (and some well financed indy's) have. If your fluid was not chenged with MB fluid, that is almost certainly the reason your trans is acting up and I would recommend going immediately to you dealer (or reputable indy) and having them completely flush out your trans with the hopes that thew damage caused is not terminal.

And the repair of the rear planetary set is going to be quite expensive if it does happen to fail.

J Irwan · #5 09-08-2004, 09:49 PM

My tranny fluid was changed by the Local dealer.
I have been servicing my car at the same dealer since I still have warranty left

.

So I am assuming this dealer should know the proper procedure for tranny fluid change.

I am just a little pissed if this is indeed a premature wear on the tranny. From the response that I have been getting seems that 5 speed auto tranny (722.6) is notorious for premature failiure. MB USA should have recalled this piece of crap tranny unit.... (sorry for the rant

).

I expect something more that can last alot longer.

Regardz,

PHAEDRUS242 · #6 09-09-2004, 09:03 AM

I've done a lot of work on these units, and although there are some catastrophies, some of them also run 200K miles without issue. It is difficult to make generalizations on a product without any sort of data to support them. Also, the C36 is a fairly powerful vehicle, and will definately put more wear on the trans than say my little 230 work beater. It's a bad deal that yours seems to be coming unglued, but sometimes major repairs aren't necessary. If you're going to keep the vehicle for a while, look into having the valve body and control unit updated to the newer style when/if a rebuild is necessitated.

Also, why would MB spend money on a recall for something that is not related to the safety systems of the vehicle? A recall has nothing to do with the reliability of drivetrain components, it has to do with potential safety hazards.

Will_w202 · #7 09-15-2004, 01:06 PM

On that note, if you need any $fluid$, I have 6 liters that I will sell for $30 plus shipping. That way, you'll only need to supply an additional 2 liters at regular cost.

Tump · #8 09-15-2004, 04:22 PM

Will_w202:

I definately need the transmission fluid. If you haven't sold it already, I'll buy it from you.

Send me an email at: mmclaw@optonline.net

Thanks,

Kebowers · #9 10-17-2004, 09:19 PM

Industry (tranny rebuilders) feeling is MBZ tranny's are poor durability compared to lots less costly stuff.

guydewdney · #10 10-18-2004, 07:52 PM

ive had the bearign mentioned above fail on a 722.6 tranny - being re-built at the moment froma 99 c36 donor 'box.

harsh changes from 3rd to 4th and 4th to 5th at large throttle openings.

J Irwan · #11 11-02-2004, 11:24 PM

On my case

it was the worn clutch packs.

The adaption value is way beyond specs....most of them has value of 210 and above 200

I was told the value need to be in the negative range or "0".

The I have to replace my tranny, and it shift so smooth now..

Regardz,

J Irwan

Nikola600 · #12 11-08-2004, 10:48 AM

Quote:

Originally Posted by M.B.DOC

There have been 2 MB 5 speed auto transmissions here in the USA. The first one was the 722.3 modified with an overdrive unit. That was only used HERE in the 1990-98 M104 engine R129 SL's & the 1992-99 300SE/S320's W140 cars.

The later 722.6 5 speed came to the USA in 1996 in V-8/12 cars & then ALL MB's from 1997, of course many V-8 2004/05 models can get the new 722.9 7-speed auto trans.

The biggest downfall of the 722.6 trans in your C36 is the lack of recommended fluid changes! The most common failure on pre-99 models is the rear plantary. MB used a bushing then & now uses a needle-bearing as a replacement on all but the 4-cyl versions.
IF you want a long lasting trans then service it at least every 30-50K miles, life-time fluids are a LAUGH in the real world! Servicing the 722.6 should run $250 +- a few $$$
A well maintained auto trans SHOULD last 200K-300K miles! But many don't!

What are your recommendations concerning Synthetic Transmission Oil like Mobil 1 Automatic Tranny Oil? I have been told not to put it in because it will delete all the friction necessary to make the tranny work, and will cause major slipping problems. I am not a tranny mechanic, but I need to understand how it will affect the tranny better. Can you help? Thank you
1995 S600 Coupe
Nicholas

BENZ TEK · #13 11-15-2004, 02:19 AM

IF you are going to be using synthetic tranny fluid that is fine as long as tranny's not electronic.I assume you're talking about your 95 car. If thats the case go for it I did. Synthetis is always going to be better that regular fluid.

yodaashe · #14 09-09-2006, 09:42 AM

Hello, New here. My 500sl transmission is gone bad, came across a 300sl wreck but engine and gear ok, would really like to know if the 300sl gearbox can replace my 500sl Thanks, yoda

jhodg5ck · #15 09-09-2006, 07:29 PM

years of the above SL's would be helpful...

However, off the top of my head I would say No.

Jonathan