Going W140
 

I plan on buying a W140 in the near future, preferably an S500/500SEL, and I was just wondering what some of their common problems are?

I already know about the wiring harness, and evaporator problems...is there anything else I should look for in a good W140?

Welcome to the dark side....:D

Check the auxiliary penumatic systems:

• Close assist. Push each door closed gently and the car should suck them in and seal them. Same thing with the trunk.
• Central locking. Lock/unlock the car with the remote and make sure all the locks operate at roughtly the same time.
• Lumbar support: With the key on, muve the lumbar support wheels on the side of each seat and verify they inflate/deflate properly.
• Backup assist: If the car is a pre-facelift model it will have two small antennas that pop up out of each rear corner of the car when you put it in reverse.
• Rear head rests: Press the switch on the dash and the head rests should drop down so you can see better when backing up. The S600 and some S500 models came with electric headrests that could be raised and lowered by the driver, but most just had the pneumatic "down only" kind.

Also, check the sunroof operation. The W140s have insulation in the sunroof cavity. It looks almost like fiber board glued in with tar. After time and hot weather have taken their toll, the glue softens up and this insulation falls down and prevents the sunroof from opening.

Just be aware that you are taking a huge risk in buying an older S-Class. If you go 1996 or newer, your get engine upgrades and the electronic transmission and OBD2 troubleshooting. But if anything goes seriously wrong with the electronics, you need Star Diagnostics to figure it out, and even then it's a challenge with all the interconnections and interdependencies. You end up in situations where you hear "Well, a new ABS/ASR module might fix the problem."

The convenience features start to fail regularly at this age. My PSE is on its second major meltdown with central locking and backup masts not working. One of my rear headrests jammed, and it was $90 for a used part to fix it, $400 from the dealer. If this stuff doesn't work, the S-Class becomes just another car, at least IMO.

I just went through a diffiicult and expensive stalling problem (documented in a recent post) that could have literally meant the end of the car if it had needed an engine or transmission module (needs an upgraded valve body). I was lucky to escape with $600 for some harness work and a new MAF.

They're a great ride when they're right, but they're cheap because they are crammed with expensive stuff that's failure-prone.

I read Chuck's post and see it as an argument for an early car, not a late one. Must be some sort of personality test.

JimF has an S500 coupe, and has probably the best website for the W140 chassis on the world wide web:

http://pages.prodigy.net/jforgione/MB_S500.html

So you guys would say that the W126 is far more reliable?

Yes....


Although, the W140 is light years ahead of the W126 though.... Superior comfort, handling, ride, amenities, power, etc.



****, I own one of the worst cars in terms of pricey maintenance (96 SL600) and problems, and its been the most reliable car we have owned..... Just gotta make sure to get one thats not been abused, from an owner who cared about it.


I would take the leap into a W140 from a W126. Like I said, its light years ahead of the W126... If you have ridden in one, you will know what I mean... The ride is absolutely sublime.

In the shop we joke around that you can take any random 140 car and find where it needs 1000$ in repairs on the spot. Better than 90% of the time it's true. We have customers that have bought used ones and spent over 10k$ to make it road worthy. You'd have a hard time giving me one.:P

Not that I dislike the 140, I just call it job security.:D

ASR...ASR...ASR! Did I mention ASR? My only experience is with a '92, but if you do a search here on W140 ASR problems, plan on an entire weekend to read them all. The problem lies in the fact that the ASR light comes on and the car goes into limp-home mode for any number of reasons, and tracking down the correct trouble can cause you to go half-insane and half-broke. Throttle Valve Actuators seem to be the biggest culprit and buddy they aren't cheap! Then to top it off you can pour hours and dollars into fixing it and think you have it beat, then out of nowhere it can happen again after 2, 3, 4 months. The other problem I had was with the vacuum pumps, particularly the multi-function one under the rear seat. If you have a problem with it and you hear it running...fix it quick or you'll be replacing it, and buddy it ain't cheap (a phrase to get used to when dealing with a W140!). Assuming you get all of the bugaboos taken care of you will own one of the most spectacular automobiles ever built.

The point I was trying to make is that at around 10+ years and 100,000 miles, these cars start to have problems that are difficult to diagnose and expensive to fix. You should not buy one if you can't afford to write it off or pay a $5,000 repair bill to keep it on the road with no guarantee that at new problem won't surface next month.

But like I said,they are great cars when they work right. I paid almost nothing for my coupe, fixed about $1000 worth of "minor" problems and it was great for 18 months. But this stalling problem was scary. No codes, no diagnostics that made sense, nobody willing to stand up and say what would fix it. Every sentence started with "Well, you could try ..."

I have a 1997 S-500 that I love - the ride the amenites, the stereo etc.
BUT it does have gremlins and parts are very expensive.
The biggest problem that I have found the 140 is the on board computer is not as specific as the newer models...meaning the codes are somewhat general - the CAN BUS system was just starting out, so not as much infrastructure in the car. So diagnosing an intermittant problem can drive you crazy!
The fix to most of the problems is worse - new control modules and they all run $1,000+++.
Find one that has low miles and good service history.
Get it checked out by Mercedes or trusted mechanic first...have them scan for any fault codes and get price to fix those (not just clear them).
The close assist is typically a problem - but simple to fix if you are a little bit mechanically inclined.
The other big 140 problem is the AC. The evaporator starts leaking and then $$$$. Mercedes built the car around the evaporator - so tons of labor to get to it.
good luck!

I joke that I can do that with any W126. I have yet to see one on a used car lot no matter how nice where I couldn't find a couple grand worth of "stuff" it needed.

Buy a late stripped S320, more simple and lots of the bugs worked out.

Seems like Mercedes people are great at doing that. Kinda irritating tho when you are the one trying to sell the car. I had one guy come look at my 300D, and basically said that it was "too rough" for the price. "Too rough" basically meant that there was a chip in the wood trim, and a scratch on the door panel. Good lord.

I'm a realist unlike a lot of people. But if you price high you better have a car that backs that up. A lot of people think whatever they own is better than everyone elses, because they own it.:D

Well, I just told him if he wanted a perfect car, then the Mercedes dealer is right down the street.