Confused by mechanics on 722.6 flush requirements

[r_p_ryan]

Hi All,

I've been regular on the forum with my older 124, but now I have a '99 210 and it's a bit over my head from a technical perspective. So I sent out a couple emails to some candidate mechanics and got totally different opinions on the servicing needs of the tranny. Below is the quote from a highly credentialed mechanic. As much as I appreciate him recommending against spending money I have some doubts about his statement:

I've attached the factory maintanence checksheet for your vehicle, which I recommend that you follow. Notice that there are no scheduled maintanence services for the transmission or differential. These components are not subject to the dirt and moisture that engine oil is, so the engineers have dropped maintanence from the schedule, as they have power steering fluid and filter change. The transmission oil filter is designed to be able to accomodate the accumulation of clutch material which occurs during normal operation for the life of the unit. If it plugs up, you have a serious problem, which is not going to be helped by new fluid. The torque converter drain has been eliminated on the 722.6 transmission in your car, so even if you want to service the transmission, only about a third of the fluid can be changed. You can change the filter and fluid if you want, about $220, won't hurt, won't help... Same deal with the differential, about $65, but not necessary.

My goal is to identify a solid mechanic in the area to perform service and repairs, and I'm curious about the forum's opinion. I reviewed the 722.6 service documentation in the WIS+ASRA and it recommends purging the fluid by removing a cooler hose. The other candidate mechanic recommends doing it every 60k miles:

The transmission service, which is done every 60k on your car, and includes changing ATF, filter, electronic plug and rear end is $537.20.

In case you're curious, below is the message that I sent to the two different mechanics:

I just purchased a 1999 E320 with 85k miles and I don't have the service history. I understand that the transmission really needs to have the fluid and filter serviced around this mileage and am looking for a quote for this service. Additionally, I'll be looking for a trustworthy mechanic in the area who can keep this car happy and me from going poor. I used to take my prior mercedes to a variety of mechanics in San Rafael, Mill Valley, and SF and got frustrated with their approach to diagnostics: keep replacing parts until the problem is fixed. In addition to the price of the transmission service, I'd also like to know your standard hourly rate, as well as the price to replace the fluids in:

* Brake system flush
* Cooling system flush
* Differential oil flush
* Engine oil/filter
* Cabin filter

Thanks,
Robert

[Mercedes Guy]

The reponse from the first mechanic is absolutely false. That was the original statement from MB but they have since admitted that the fluid should be changed. Apparently 722.6 transmissions started failing and they discovered that there is no such thing as "lifetime" transmission fluid. From what I've heard, MB's response was that they never specified the length of "lifetime" and so many speculate they meant the lifetime of the factory warranty.

It's actually quite easy to change the fluid on 722.6 transmissions. I'll see if I can find the thread on this forum that shows how.

[Mercedes Guy]

Here is an excellent thread on changing the fluid in the 722.6:

722.6 Transmission Fluid Change with pictures

It's not really much different than changing the fluid in any of the older MB models. You just need a few more specialty items such as the dipstick, specific ATF fluid, and plastic pin to secure the cap.

I know that my 140 has the drain plug on the torque converter. I believe it was eliminated in the late '90s, though, so yours might have one. Seeing as how that first mechanic never recommends changing the fluid or filter he may be wrong on that as well.

I changed my 722.6 fluid myself, but just out of curiosity I checked with the local MB dealer to see what they charge. It would have been about $230 to have them do it. The response from the second mechanic seems expensive. Why replace the electronic plug and "rear end" if there's nothing wrong with it?

[r_p_ryan]

Thanks - I guess I should just start learning my way around this car too. Sounds like I shouldn't take the car to either of these mechanics, and they are the higher rated ones in my area. I've been a bit intimidated by this car as it's much more 'electronic' than my '89 300TE. But it sounds like I need to choose between doing it myself or getting charged too much.

[mpolli]

There was an issue with the "plug", which I think there is a better name for it. I think some were leaking fluid. Most people agree that the trans should never be "flushed." Some believe that it is better to leave it sealed than to change the fluid. But most seem to believe it is better to change the fluid. I thought the second mechanic sounded pretty honest, and he was going by what was originally published. I would give him the new info and get a second response and quote for the fluid change. BTW, the cabin filter is pretty easy to do on a W202, I would assume not too bad on a W210. The oil change should not be too bad, although the plug might be hard to remove if it has never been loosened before. Mine was, but is a different engine. A lot of people recommend the vacuum system for the oil. I drain mine.

[bobs]

If I recall correctly, the M-B's official stance on the 722.6 it that you change the fluid once at 39,000 miles (60,000 km) and then it is sealed for life. Considering how much they cost to replace (don't ask me how I know!), I will be changing the fluid and filter every 40,000 miles or so. It's cheap insurance if you ask me!

[dhjenkins]

Like almost every fluid in a vehicle, trans fluid has additives that wear out and must be replenished. Sometimes you can get a simple additive booster, sometimes you have to drain & fill. Personally, unless you've always done a power flush, I recommend against it - it just loosens up crud that would otherwise sit their peacefully and gets it lodged in passageways.

Point of fact - "regular" oil is about 75% oil and 25% additives. The additives include anti-corrosion, anti-friction, anti-shear, particle encapsulants, etc... The additive package in most oils is what allows them to pass the almost laughable ILSAC & SAE tests to get their viscosity rating, and due to the woefully short testing run times, those oils generally would not meet their printed ratings after as little as 500 miles in your engine.

[lkchris]

Forget the concept of "flush." It's only applicable to your wallet.

On the trans, just drain, replace filter, and refill.

http://www.thecarconnection.com/article/1008972_mechanics-tale-the-flushing-of-america

[Hirnbeiss]

'99 W210 should still have the torque converter drain plug, at least mine does.

[jhodg5ck]

The .6's kept their TC drain plugs for a while, but did in the end lose them.

I like to see service (condition dependent to some extent) every 30-40K.

If you do Not have a drain plus on the TC, I service the filter/drain the pan, refill, drain and repeat till I've run about 9 qt's through the AT.

Also, if you do not already have one it's a good idea to add a magnet to the pan, MB makes a Very nice one w/ a lot of surface area!

The plug on the .6 is common, as is having to change the conductor plate. A quick code rear on SDS will alert your tech when issues start to occur and should be able to give you some warning..

Jonathan

[Hirnbeiss]

This is generic, but gives an idea of how to excahneg the torque converter fluid without a drain plug.
http://www.amsoil.com/faqs/ATF_and_Filter_Change_Procedures.pdf

[300EE320]

Excellent! That's the info I was looking for in the other thread on this topic. :-)

BTW, I changed the diff lube at the same time. That was the easiest job.

One tip on the engine oil drain that has served me very well is to use a 6 point 1/2 inch socket on the bolt. 1/2 inch is equal to 12.7 mm, and fits the bolt perfectly. If you use a 13 mm, especially a 12 pt socket, prepare to have problems...

[mpolli]

Originally Posted by 300EE320

One tip on the engine oil drain that has served me very well is to use a 6 point 1/2 inch socket on the bolt. 1/2 inch is equal to 12.7 mm, and fits the bolt perfectly. If you use a 13 mm, especially a 12 pt socket, prepare to have problems...

That is a good idea! Definitely don't use 12 pt of any size.

[r_p_ryan]

Great link to the flushing process, and nice tip on the 1/2" socket. I reviewed the WIS+ASRA literature and the flushing process is very similar - remove one of the cooler lines and flush out 3 liters, then top up and repeat. The literature notes that a total of 15 liters of fluid will be required.

I picked up the parts from the dealer including the dipstick tool, plug, and magnet. I'll update the board with the quantity of fluid used.

[samiam44]

Also note:

Don't need to Flush most things: diff, coolant, brake fluid. Simply drain and replace. Of course, brakes that is bleed through the system.


M