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1997 Mercedes Benz S420
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3 Posts
Discussion Starter #1
Hi all:

I am a new member of the forum. I just purchased a 1997 S420 (I am the third owner) and the car has 75k miles. I brought the car to an mechanic who used to work on my previous cars (1985.5 Porsche 944, 1993 BMW 735i, 1993 MB 400e, and a 1989 Porsche 911) for a quick overview. He said the car was in great shape except for the following:

1. Rear rotors/pads needed replacement.
2. Front passenger wheel bearing needs attention.

Otherwise, the car is in great shape (no leaks or any other major issues to address). For PM, I asked that he flush all fluids (brake, oil, transmission, coolant). He told me that Mercedes said the transmission fluid is lifetime and should not be changed. Does this sound correct? In addition, does anyone recommend that I have a tune-up performed? Lastly, does the timing chain need to be adjusted/replaced? I really appreciate any suggestions regarding the PM of my new car as I am not the most mechanically savvy person. Thanks in advance!

Dan
 

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1999 Mercedes Benz S320 Long Wheelbase.
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544 Posts
First of all, welcome! You've got one hell of a car there, take great care of it! I see you're no stranger to the Premium German Automobile, so the repair bills won't be as much of a shock to you! Haha!

Secondly, Mercedes says that the Tranny fluid is lifetime, but it's not. I had mine flushed shortly after I bought mine, at roughly 73k miles, and I've had no bad side effects from that, and I firmly believe that it will prolong the longevity of the transmission.
 

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Premium Member
1997 S600 (sold)
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4,660 Posts
Congrats on the car. Hope it treats you well.

A couple of comments on your questions. Your W140 will have the 722.6 electronically controlled transmission. Mercedes did say that the transmission fluid is lifetime fill, no changes needed. If you read threads on this site, however, you'll find people who say that dealership service departments say that MB has changed their minds on this issue and now recommend changes. Perhaps this is backed up in a TSB. I'm not sure. I cannot comment. You can change the fluid just like any other transmission. Your decision.

There's not really much involved with a tune-up for the fully electronic ignition cars. Change oil, change spark plugs, change air filter, and you're pretty much done. The rest you fix when the car tells you it's broken... sort of.

For the timing chain, there are a couple of recent threads worth reading, especially the one started by "Mercedes Mechanix". Basically, it's almost no maintenance, but there have been reports here of timing chain stretch to the point that poor running resulted. The bigger concern most of the time are the plastic guides and rails as "Mercedes Mechanix" describes.

Brett
 

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07 GL 450, 00 E320 Wagon, 99 S500, 93 400E, 87 EURO Testarossa
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139 Posts
chip342 - I previously owned an e320 sedan and my merc mechanic followed the advice of lifetime tranny, but our tranny was destroyed at 180k (estimated costs to repair, 6-7k) so we had to dump the car and replaced it with a e320 wagaon for just a few grand more and less than half the mileage. However, mercedes, and my merc mechanic confirmed, has changed their policy of lifetime tranny and now recommend tranny fluid changes. I highly recommend it! My merc mechanic (german immigrant) is great and I would not take my benz to any other shop.
 

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93 500SEL & 99 S500
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1,022 Posts
I have heard the same about tranny fluid change, but I do not subscribe to it. Since I have purchased my 500SEL (Had 59,000 miles on it when I bought her), I have had the tranny rebuilt (failed the first day I brought her home), and have replaced the fluid at least one other time.

As for tune up, I agree you should get one. No matter what you may think you know about the car's history, it is a good idea to do a full tune up. Replace the spark plugs, new air filters (I personally would recommend K&N as I think they are worth it), new fuel filter, flush coolant, brake fluid, tranny fluid, hydrolic fluid, change oil with synthetic, replace necessary pads and rotors, get a good alignment (I would recommend the dealer for this, and this only), and finally get tires properly balanced.

The above will make the car feel like a new Mercedes and keep her running smoothly for years to come. I perform the above every few thousand miles. (Change the spark plugs every 15,000 to 20,000 miles, oil every 5,000 now that I use synthetic, brake fluid every 30,000, etc. etc.).

Now, before you perform any service (oil change included) go to your local dealer and get 2 cans of this fuel injector cleaner they make. If you ask the parts department, they should know what you are talking about. They are around $7.00 each. Poor them in to your tank while it is empty and fill it with premium (with as little ethanol as possible) gasoline. Empty the tank, fill again, drive another 100-200 miles and then bring the car in for all the service I mentioned above.
 

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1997 Mercedes Benz S420
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3 Posts
Discussion Starter #6
Thanks!!!

Thanks to everyone for the fantastic advise! I am sure I will have more questions as I go along. I absolutely agree with everyone's philosophies regarding the transmission fluid flush. I will be sure to have that done. Thanks again!

Dan
 

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CL 500 // S 500 L // E 320 T
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548 Posts
Just be sure they use the original special transmission fluid provided by Mercedes-Benz for the 722.6 transmission when doing the flush. It is a special fluid which costs three or four times more than regular transmission oil BUT you must definitely do change, at least every 50,000 miles.
 
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