Transmission Life Expectancy
 

Have the transmissions used in the ML been used long enough to have a record as to how long they will last. With my older Mercedes cars and thoses of my friends I found that if the transmission lasted between 125k miles and 175K miles we did pretty good. Any less miles we were dissappointed and with any more we were quite happy.

I personally know of a E300D with a 722.6 that at the last point I knew had gone 275,000 miles without so much as a fluid change (that everyone insists has to be done). It is the same type of trans as the ML.
Gilly

That's certainly encouraging news. Do you think an E300D would put any less stress or more for that matter on the gearbox than an ML?

I don't think it would be much different, unless you are an aggresive driver. The vehicle being discussed was owned by a salesman who put the first few hundred thousand on it and did maintenance only per MB literature (maintenance book/FSS, no more, no less), the guy REALLY piles on the mileage.
Gilly

Mine lasted 30,000 miles
 

I have seen some posts about the transmissions on the ML 320 going out early. I had 30,000 of VERY easy driving mixed equally between city and highway and mine needed to be rebuilt at 30,000. On the other end of the spectrum I have also seen posts of MLs in the 100,000 + miles and still going strong. To get this many miles in a few years likely means highway miles, which are probably easier on the vehicle.

I also recall seeing somthing about the specs on the transmissions were different for the ML 320 vs. the ML 500.

So there's your answer, somewhere around 30,000 to 300,000 miles. Depending.
Yes the V6 and V8 transmissions are rated at different torque inputs. Internally they are known as the "small NAG" and "large NAG" transmissions.
Somewhere I have a spec sheet that lists the different torque ratings between the 2. The smaller one is for 4 and 6 cylinder engines (incl diesel, this is for the 722.6, not sure about the CDI, I think that's the new transmission) and the large one is for the 8 and 12 cylinders.
Gilly

A Chandler dealer's SA was reviewing my 98 ML320s service history and when he noted 123,000 miles he suggested I start saving up for a new transmission as he felt 125,000 was about the average. $5000 plus for a dealer replacement.

I immediately changed the ATF to Mobil 1 (not factory fluid) and am now at 131,000 miles. My 79 300SD, which slipped for years, is now shifting as good as new and has 261,000 miles with only a new accumulator. Also on Mobil 1 ATF.

It should be noted that when a dealer declares a transmission dead, it is the only expedient thing they can do to minimize come-backs. The first failure could be as simple as a gear selection solenoid failure, easily replaced, but probably the first in a chain of failures that the dealer would wish to avoid.

Just my opinion, YMMV.

Jim

Don't be surprised when the tranny IS smeared at 125,000 miles since you're not running the factory fluid.......
Gilly

Transmission early failure
 

Gilly,

I am well aware of MB stance on transmission maintenance: They say don't EVER change the fluid, it is good for life! But if you do, you have to use our fluid. Well, given the mostly negative results of their directions, I'll take my chances with Mobil 1 ATF.

Personally, I expect any automatic trans to last more than 125,000 miles.

Regards,

Jim

I will admit to being totally mistified by this whole transmission thing. To me, sealed for "life" means it's sealed and should never fail as long as it is driven withing the stated parameters. Now I am seeing experts telling us that a "newer" MB will only get ~125,000 miles on a tranny. That seems awfully short. My '90 420SEL had 197,000 and was in great shape, my '72 280 SEL 4.5 has 176,000 and the tranny is tight as a drum......hell, my '87 Chevy Blazer has 190,000 and it spends much of its life bashing through the Arizona mountains and deserts.

The key (at least I thought) was to change tranny oil every year. Now MB is saying never change the oil, and Oh Yeah, it will run for life but life seems to mean ~125,000 miles. If you do change oil use MB....if not it will fail. I'm sorry folks, but there seems like a disconnect here.......I must be missing something 'cause this makes no sense.

Yeah you're missing something. You're "missing" all the thousands and thousands of 722.6's that are running around with the original factory fluid (never been changed) that are doing JUST fine. ALL you hear about are the small minority that fail, and failures that are not attributed at ALL to the fact the fluid had never been changed. You coulda changed the damn fluid every 10,000 miles if you wanted to, and they STILL would have failed. Can't make anyone believe that though........

Gilly

Transmission on ML320
 

Replaced one at 123,500......guess it was a mis daignosis on the dealers part....would not give the code printout (original report)......I wrote to MB also they said they couldnt anything......I think it was the low range motor all along and that was done for free after 5 months because transmission was acting up again with the new one also.....so a low range motor was put on for free......because once before when the transmission did not shift a low range motor was replaced......all its life the same dealer had done all service including oil changes....

'99 ML430 102K Tranny probs
 

Bought a '99 ML430 with a bad transmission so I could educate myself on fault diagnosis and rebuild techniques; instead I got schooled on how many parts in that propulsion unit have been updated and are no longer useable when putting it back together again. The transmission itself tossed the entire planetary gearset (all three -- love auction cars, everyone has to drive it to make sure it's bad), and I originally thought it was the typical mercedes planetary failure where the center bushing that links the front shaft with the back shaft wears excessively and fails, pinching the bearing surface and shattering the bearing, causing catastrophic failure as the individual hardened steel needle bearings are fed through the planetaries (the update replaces the bronze bushing with a roller bearing, requiring the purchase of the front shaft and tail shaft assembly.

The sungear assembly is updated (main sungear almost always fails, and requires purchase of entire sungear assembly); the rear planetaries are updated; the bearings in much of the transmission are updated (requiring replacement of MUCH more expensive componants). But I'm a trooper, and even though I could have bought a completely rebuilt tranny for the price I paid for the parts ($2700 wholesale), I learned quite a bit. For example, there are not many good sources for used parts, because so many things were updated, and WHEN these transmissions fail, they like to toss the planetary gears. Also, the failure in earlier transmissions is due to to poor designing on Mercedes part (later transmissions are much more durable); the earlier transmissions ('00 and earlier 722.6) require fluid changes, and given the weakness of the center bushing, about 50-60K on the fluid changes seems about right (given that the tranny weakness is on a transmission already past that service period on an older vehicle anyway, I don't like my odds, particularly on the higher-output engines). I'm sure the newer tranny's are more durable (I can attest to that... mine is updated, and the transmission design IS more durable).

Which brings me to why the transmission failed in the first place... the front sungear to rear planetary bearing failed (the bearing was updated as well, but still has a weakness in the planetary design with that bearing, IMO). Bearing failed and little needle bearings greeted the planetary; they did NOT get along at all. That torrington still needs designed IMHO (I'm full of it tonight). I'll update (no pun intended) as I get time, but runs great now.

Mechanically, the internal difference in the transmission regarding the torque output I believe is such: lower torque outputs have a 3-wheel planetary drive, and higher output tranny's utilize a 4-wheel gearset.

BenzRepair.....that was an extremely informative post. For those of us that have lower mileage vehicles (my '98 just turned 80K) the question of changing fluid is is still a confushing issue, should we or should we not? And if we do will it really by us anything. Then there is the fluid issue. I suspect that the MB fluid is a synthetic and the change to a commercial grade (i.e. Mobile One may not be to our benifit.

You think that the 50K change interval may prolong our tranny life, and if the cause of premature failure is mechanical wear, that make a lot of sense. Granted, we are not going to reverse damage, but it should give some benifit.

What are the early symptoms these tranny's exhibit once they start down to slippery road to failure? With all the mods MB has made over the years, it would seem like we have two options: 1) Drive it till it fails completly and replace it with a quality rebuilt, or 2) Get it fixed as soon as it starts displaying the early symptoms.

Change the oil
 

My dealer told me that the cost was $300 for the transmission oil change. Compare that to $3,000 for a rebuild. To me the answer is simple, change the oil every 4 years or 100,000 miles (just like you do with the spark plugs). Even if it does nothing, it certainly won't hurt.

As for symptoms, a few are:
- shifting points are off
- sticks in a gear for a prolonged period
- sliping

I normally charge $200 for the tranny oil change, but I get my fluid for $6.50 a liter (we have 2 dealerships in town; the other charges 2X as much). I still like 50-60K intervals, and I do not care what anyone else says, but the life of your engine and transmission is controlled by your fluid, and when your fluid breaks down or is too heavily contaminated, it will not provide the protection required to maintain its service life.

Wear in an engine and transmission is caused by friction, and excessive friction is caused by compromised fluid (coupled with poor designing, such as lack of lubrication, excessive loads, etc.); keep your fluids changed on a regular basis (I tell my customers 5000-7500 miles with synthetic, 2500-3000 miles with conventional oils) -- this is the most important rule in car longevity, keep the fluids changed and topped off (well, that and put gas in it, but people figure that out pretty quickly). Do this, and I guarantee you a very long life with your engine and transmission mechanically (unless overheated, etc... you know what I mean).

I have talked to some of the best dedicated rebuilders in the country on this tranny series... they say two things: "No, we do not have any spare parts available" (this transmission tosses the torrington bearing between the sun gear and front of the output shaft, and it tears EVERYTHING up), and "Keep the fluids clean; change fluids often". Now while the transmission may have a good average when not changing the fluid, it is not that expensive to change it out when comparing cost-per-mile, and there are no consequences I am aware of to changing fluid out too frequently.

Will post about warning signs later.

If you put this in writing, I'd be your best customer.

I wouldn't argue this. I don't think it "hurts" anything to change the fluid (assuming it is done properly and with approved fluid), personally on a 722.6, I feel it's a waste of money.

Gilly

I know, I'm real big on "overkill" (I require 2 fluid changes on transmission rebuilds within 10,000 miles, and 4 oil changes on my engine rebuilds, but go figure, I AM a mechanic). I only have around 100 MB transmission and engine rebuilds under my belt personally, but I've not had any returns yet for mechanical problems either. I do warrant transmissions for up to 2 years; anything after that, if I feel it I am at fault or responsible in some way for the failure, then I usually take care of most if not all of the repairs.

On the engines, however, we have no competition within a 500 mile radius, and if the rebuild and cylinder sizing are done correctly you can get a minimum of 200K out of your engine (with proper oil changes and no overheating). The customers with warranties are required to change their oil at early intervals to cover the work done; no wear-related warranty work has been carried out in the past 5 years, although there have been problems with existing excessive wear on parts that was missed until the transmissions were put together (K2 drum circuit clearances, to be exact... I always pressure-test now).

Transmission Warning Signs
 

Some things you can do or watch out for:

Watch for 3, 4, 5th gear acceleration slip; it's one of the signs that your transmission control module (TCM) could be bad. This can be a result of a defective earlier design, or it could be shorting out in the transmission because of excessive wear.

If your vehicle lets out a loud "bang", it's a telltale sign you just tossed a bearing and your planetaries got tossed; it could still run at first, but will soon be painfully obvious that the tranny useful life is likely at an end (I guess what I'm saying is there is no warning when the #1 cause of 722.6 transmission failure happens; I don't know if the defective bearing set is too much slack/excessive slap, or too much stress/friction).

Missing shifts or harsh shifts are not necessarily consistant with internal transmission problems on the 722.6, and can often be fixed without removing the tranny. usually either TCM or solenoid(s), electronic VB wiring harness, or to a lesser extent the valve body itself. A proper diagnostic readout will often tell you exactly what the problem is, however, as the TCU records tranny componant fill time, pressures, temps, and cycles.

One of the best things you can do for your transmission (if you change your tranny oil) is to install a magnet in the bottom of your oil pan (when I find the # I'll post here).

Your transmission will whine loudly when the filter is plugged; this is usually a bad sign, as it indicates solids loose in the tranny to plug it (planetaries, sprags, bushings, bearings, etc.). The filter is very coarse compared to earlier MB filters, and it takes alot of solid material to plug it up.

Mine did the first two until fluid was changed at 120K. MB fluid.

Tranny service
 

Hi I have 97 E 300D with 264 k miles on it. I change 3.5 q. of MB t.fluid and filter every30 k.milesI dont now haw to open converter plug so drain only half of Atf.Works fine for me...

Transmission Fluid and Filter Replacement procedure
 

There is a whining noise coming from my 99 ML430 with 84K miles that could be from the transmission. The noise is present always when engine is on and follows the RPMs of the engine (makes no difference with serpentine belt off). If what you say is true about clogged filter then I may be in trouble. The transnmission is working fine, however, I have been through this before and I know something is not right and it is a matter of time before major $$$$$ is required.

Will a fluid and filter change be appropriate if the noise is from the tranny.
Should a Mercedes shop do this or can a DIYer that enjoys working on cars do this?
What are the steps and what should one look out for?

Given the scenario you might want a shop experienced in 722.6 transmissions (Notice I DIDN'T say DEALER, although a dealer is an option) to see what kind of muck might be in the transmission pan and determine if the transmission is junk or not.
Gilly

Changed ATF fluid and Cooler Lines
 

99 ML430 85K miles, 722.6

I just changed the ATF fluid, filter, and cooler lines. There was a slow leak in one of the cooler lines causing the fluid to be low. I decided to replace all ATF fluid and filter while I was replacing the cooler lines.

I could not order just one cooler line, you must order the set, got it cheaper at http://catalog.peachparts.com than from dealer (special order item). Part # 163-501-06-24

Torque converter drain plug tip: It is easier to have one view the torque converter for the drain plug while the other turns the crank slowly. A 17 mm Hex bit is needed to rotate the crankshaft pulley.

Old fluid was very dark but the bottom of pan looked rather clean. I decided that the trace amount of metal shavings was acceptable but I am no transmission expert.

I installed the magnet, part # 220-271-00-98, toward the middle of the pan near the drain plug. New filter and pan gasket installed. I purchased new pan bolts just in case, part # 003-990-02-12, quantity of 6.

I put a total 8.5 liters of ATF fluid in before I got a full reading when transmission was hot (80C). I figure the extra liter was what was in the cooler lines and radiator.

I still have whining noise, however, definitely from engine. :confused: Oh well, I can live with it.

The transmission in my 99 ML420 failed at 85,000 miles as I pulled up to a red light in downtown Toronto. I was 2,000 miles from home so this was an expensive event. It limped along for 6 blocks or so before there was no connection whatsoever between the engine and the wheels.

When the pan was pulled, there were large chunks of broken gears in it. Apparently this "sprag failure" is not entirely uncommon on 98 and 99 MLs.

Fluid had been changed at 45,000.

RICK T $300 for a transmission Fluid change ?
 

I just want to make sure I read that right. $300 to unsrew a drain plug and pour in some ATF. maybe swap a filter.

I agree, but YES, that is the price that my dealer in Sacramento charges. I think someone else mentioned that they have seen prices range from $200 - $400 from various MB dealers.

Steve
Seems a little high, but remember the fluid is approx. $15/liter, times what, 7 or 8 liters. And it does take a bit of time to get the fluid level "right on the nuts". MB is critical on the level, as I'm sure you've read. Total job time you'd be hard pressed to get it done in less than an hour and do a good job at getting the level correct. Most dealers have to be pushing $100/hr labor rate, at least $75, and out west probably over $100? Anybody verify?
Gilly

$110 per hour in Sacramento.

Here in the UK, the MB dealers charge £90 per hour labour....about $180..!!!!

Trans oil change
 

Does anyone know if changing the trans control unit will required a fluid change? :confused:

Only if the version of the control unit is updated and it requires valve body change. Then you'll need to pop the pan and might as well change the fluid.

Gilly

Getting Fluid Out of Torque Converter
 

I was going to try to change the AT fluid and filter myself. However, I was told that 1/2 of the old fluid will remain in the torque converter unless I drain it too. How should I handle this? Is it difficult to drain fluid from torque converter. Or, should I change the fluid a few times to get it clean? What do the service techs at the shops do? Thanks for any advice!

By the way, I've got 99 ML320 with 95k miles and fluid hasn't been changed. This will be the first if I can find out how to do it.

Very easy to drain, at least on my 1999 ML 320. There is an allen head bolt that you remove from the torque converter, it's small maybe 5 or 6mm. You just turn crankshaft from front with I think it was a 27 or 32 mm socket until you see the allen bolt.

Regarding the torque converter draining, try this link, it is a posting of an article in the Star Magazine with clear directions and pictures on draining the trans fluid:

http://www.benzworld.org/forums/forums/thread-view.asp?tid=1182558&posts=7&hl=

The picture is upside down but the information is clear enough.

You will be too when you're doing this job. I agree with Ron, quite easy. Your '99 has a drain plug in the torque converter, but the newer ones don't; it was discontinued at some point. :eek:

On my '98 you turn the crank with a 17mm hex driver.

Thank you all! Very helpful. Will try it this weekend. EOM
 

Thank you all! Very helpful. Will try it this weekend.

Tranny dipstick
 

I bought all of the stuff to change the tranny fluid and filter. Most of the information on this forum is accurate but a few things were left out and I have 2 questions.

Be sure to buy two of the seals for the cooling hoses as you will probably need to loosen or remove the one on the driver side attached to the bell housing. Be sure to get both old seals off the banjo bolt to avoid a leak.

On the passenger side there is a cover over the electrical connection to the tranny and you should remove it before undoing the tranny pan bolts.

Two questions:

What is the torque for the pan bolts?

My dipstick would not go down the all the way. It seems to bottom out with about a foot to go. The reading seems just fine however. Is this normal?

Thanks.

What is the torque for the pan bolts?
8NM

My dipstick would not go down the all the way. It seems to bottom out with about a foot to go. The reading seems just fine however. Is this normal?
If it's the one for testing the level I don't recall it going all the way down either.

That's correct.
8nm on the pan,
And the dipstick does not go all the way down. I think it was produced that long because the 140's have a really long dipstick tube, and that dipstick is made to check 722.6 tranny's on any benz.

Just to update the 722.6 transmission file, MB now subs all parts directly related to the planetaries to a full planetary assembly, taking all the options out of rebuilding. After you pay more than $2K for that part/assembly alone, then a few other necessary updated parts, you may as well just buy the transmission from Benz; there's too many other parts that can go bad in that transmission to justify saving a few 100 dollars on an aftermarket rebuild. Be careful with used parts; remember, you're replacing fatigued and failed parts with known defective parts, and you're just looking for trouble unless you just want to unload your vehicle. This absolutely sucks, as this was a most enjoyable transmission for me to rebuild.