Jaywalker

I've owned a lot of cars and am now considering an MB, probably a W210. In my research I've found reference to a service shop's use of a "Star" machine that allows wondrous things, including changing transmission fluid with more precision that I ever thought necessary.

I've changed transmission fluid since the early Seventies (my first auto trans), and have got around the torque converter issue by doing the change twice, about a 1,000 miles apart - it doesn't all get changed, but more than just a simple, single drain would.

What is it that MBs measure with their tools that I can't do with a wrench and screwdriver, the same way I've been doing it for years? I understand they want to empty the torque converter, but if I stay '99 or earlier there's a torque converter plug (fantastic idea!). I've read some temperature measurements but don't understand what's behind this issue - what are they measuring and where?

I'd be glad to take a link as an answer - "transmission fluid change" brings up many, many responses.

Thanks.

fosmith

Sounds like you've been doing your research. The Star diagnostics would be able to pull up stored fault codes in the transmission control module but if the trans is operating properly, there probably aren't any codes stored. There's no transmission dipstick so the "tool" you need is a dipstick that you insert in the fill tube after removing the sealed cap. You can get this from the dealer, on ebay or from Ohlord. You can't leave the dipstick in so you'll have to get new cap to reseal the fill tube when you're done. The fluid level measurement on the dipstick depends on the trans fluid being up to operating temp, which I think is 80C. Some use an infrared thermometer to measure temp but you can just let the car run for while. Correct level at the correct temp is essential, however. Also, there's an article somewhere in the Benzworld stickies about complete fluid change in a 2000-02 trans by disconnecting the cooler line at the radiator, attaching a tube to a measured container, starting the engine, pumping out a liter or so, topping up with the same amount and repeating until clean fluid comes out.

Fred

RichardM98

First of all your experience with older cars, while useful, can get you into trouble with a MB. In the 'good ole days', you drained the transmission and replaced the fluid with whatever quantity the transmission held like an oil change. As mentioned by Fred, the level is much more critical in the electronically controlled 722.6xx transmission in the W210s. There is a special 'dipstick tool' (about $30) used to set the level. After servicing, the liquid level must be adjusted correctly. Too little or too much and you run the risk of transmission damage. Will it blow up 2 miles down the road? No, but it may fail sooner than you would like. And it's a $3K-$5 repair bill. Also there are only two approved MB fluids even though some ATF suppliers CLAIM their fluid will work. The level must also be set when the transmission is at the normal operating temperature (80C) and the car is on level ground. Setting the level at a lower temperature will result in an overfilled condition when everything warms up.

Many who don't have the drain plug on their torque convertor do as you have and make a couple of changes. You'll get about 1/2 out with only draining the pan. Disconnecting a cooler line and running the engine to force out additional fluid is risky. But some do it.

As for the dealer, they hook up the SDS which can read the transmission temperature and check for adaptation codes as Fred mentioned. They also have transmission flushing machine which can preheat the fluid and extract the old fluid while putting the new fluid in. In some models the SDS can use the suspension control system to shift the car's balance and get even more out of the 'nooks and crannies'. I don't think that's available on the W210.

W210's are good reliable models. They have decent performance for a V6 and are safe to drive. 4 and 5 star crash ratings when new. They can be expensive to maintain if you must go to the dealer for every little thing. Doesn't sound like that applies to you. There is a older thread in this forum called something like 'Common Problems'. If you haven't done so you might like to read it as info for prepurchase inspections.

Good luck.

Jaywalker

Thank you both - those are excellent answers. Like all of us, I have to choose what I'm willing to pay for and what I'll do myself. Transmission fluid changes may fall into the "pay for" category, once I think about it. After all, it happens only at 40k mile intervals. You're exactly right about having to adjust expectations to Mercedes think.