Notes from beyond the Dark Side - Page 2 - PeachParts Mercedes-Benz Forum

kalpol · #16 01-05-2007, 09:22 AM

Quote:

Originally Posted by Benzcrusher

The system is very similiar to the set-up on the w123 300TD as well as the w126 560SEL / SEC and special ordered w115 /w123 sedans.
The struts fail when they leak and are fairly durable. They are stupid expensive to replace with new ones ~$650 each. There a two types of rear struts as hydropneumatic front shocks were an option. ..

On my 84 500SEL, the nitrogen spheres had degassed, causing a super harsh ride - they were about $130 each, I think, and there were five. If the ride quality is OK, I don't think the problem is in the strut or sphere. A clunking noise can be anything from the muffler hitting something to a bad bushing somewhere. Of course, I know nothing about W140s.

airedale · #17 01-22-2007, 09:23 AM

Quote:

Originally Posted by ctaylor738

If it's OK with you guys, I will open this thread, and update it as I work on the S500 Coupe. Normally this would not belong here, but it might be of interest to see how the cars have evolved, and to those who are considering the purchase of a newer car.

So last night was brake pads. Parts were not so bad - $134 for pads and sensors. But my first challenge was lifting the car. There is no single point to jack the car up in front, so I resorted to a SUV floor jack under four very convenient rubber lift points, stuck a jackstand under a frame piece, and did one wheel at a time. This worked well enough, but the size of the car forced me into some cramped and poorly lighted areas to do the rear brakes.

The brakes themselves are conventional and look a lot like 123 brakes. The front calipers have four pistons each, the rears two. The front have one sensor on the outside pad. Only the right rear brake has a sensor. Replacing the pads was straightforward. The only annoyance was that the fluid reservoir is covered with a large plastic piece that runs across the firewall and has amazingly inconvenient screws to remove for access.

Book time for the pads is 1.8 hours, and I ended up at about 3.

So tonight I will start on the oil tubes which involves removing the valve covers and, apparently, the ignition coils and fuel pipes.

WOW! I have accepted your SAGE advice since I first joined this forum and considered changing my, at the time recently acquired 107, from R-12 to an alternative. Very glad I listened to you and stayed with the R-12 and found the source of the leak. Even if I had not found the leak R-12 would have been the right choice had if I only had to top it off annually.

Anyway my comment is:
Thank You for being here!
You know your Mercedes Stuff!
P.S. I even remember when you offered " Buttercup " a 380SL engine you had. What a touching thread and what a Gallant gesture of you. I hope she and the family car turned out OK.

ctaylor738 · #18 03-07-2007, 09:38 AM

I have my new nitrogen spheres and suspension fluid sitting on the workbench waiting for a combination of warmer weather and some time to do the job. Last week, however, I had the transmission serviced (ouch!) at JCP Motorsports in Alexandria (very good shop, so far), and discussed the clunking with Carlos. His analysis was that if the spheres were blown, there would be no give in the suspension at all, and he demostrated this by bouncing the rear of the car a couple of times. His diagnosis was the rubber buffers that screw on the top of the hydraulic strut and sit between it and the frame. So I ordered a pair and plan to install them and see if they fix the problem.

ctaylor738 · #19 03-07-2007, 10:22 AM

Another opportunity to repair came during January. The car sat most of a week in a very cold garage at Dulles Airport, and when I returned from my trip, the reverse assist masts, trunk close assist, and power antenna had quit working. I thought that these failures might be related, but this turned out not to be the case.

The antenna started working on its own a couple of days later.

The assist problems turned out to be more complicated. There are two vacuum, actually better termed pneumatic, systems in the car. One handles the closing assists, and the other central locking, reverse assist, and lumbar support. For those of us used to the 114 or 107 systems, re-education is needed. The systems use both vacuum and pressure to make things move, and the same pump can produce both!

Here is an excellent guide to the basics of the systems.

http://v12uberalles.com/Closing_Assist_Pump.htm?

It turned out that the closing assist pump and controls were working, and the issue seems to be with the mechanical adjustment of the latch. Working on that.

The reverse assist was a different matter. I removed the rear seat cushion and put my hand on the pump, and operated the door lock switch. There was a click but the motor did not run. So I removed the pump/control unit and took it apart. There is a harness with a total of 23 wires running to it.

See the picture. You can see the motor with the pump at the bottom or the right side. You can also see the valves and circuit board that control wiat gets air of vacuum as well as the fittings where the various lines attach.
Behind it is the case that fits over the top. Pretty neat.

What I discovered was that the pump motor would not run even with 12V put directly to it. I then discovered to my dismay that the replacement pump is over $400 and of course that motor is not available separately.

So when in doubt, call George Murphy. As it happened, he had a pump with a good motor, but other problems, and he is sending that to me for a nominal amount.

Stay tuned.

ctaylor738 · #20 03-12-2007, 09:07 AM

I installed the new buffers on the top of the struts over the weekend. The good news is that, at least on the 140 coupe, you don't have to disconnect the hydraulics to maneuver the strut into a position where you can work on it. You simpley remove the nut in the trunk, jack the car up, unbolt the strut from the control arm, pull it down, and get it into a semi-convenient position. Then you put a pair of channel locks on the strut, vice grips on the "neck" of the buffer, and unscrew the buffer. See the first picture.

That worked fine on the right side, which took about 30 minutes.

The left side was another matter altogether.

I could not get the buffer to budge with the small amount of leverage that I could get with the vice grips on the neck. So I jammed two nuts together on the top threads, only to discover that the rubber inside had disintegrated so that the buffer would turn freely. So I resorted to cutting the outside metal with a Dremel tool, and then griinding the aluminum inside the buffer, where the majority of the threads are, to release the buffer from the stud on the strut. About three hours on that side. See the second picture.

Anyway, this all had a happy ending. The clunk is gone. Anybody need a pair of nitrogen-filled accumulators?

Mark DiSilvestro · #21 03-13-2007, 07:48 PM

Quote:

Originally Posted by ctaylor738

I installed the new buffers on the top of the struts over the weekend. The good news is that, at least on the 140 coupe, you don't have to disconnect the hydraulics to maneuver the strut into a position where you can work on it. You simpley remove the nut in the trunk, jack the car up, unbolt the strut from the control arm, pull it down, and get it into a semi-convenient position. Then you put a pair of channel locks on the strut, vice grips on the "neck" of the buffer, and unscrew the buffer. See the first picture.

That worked fine on the right side, which took about 30 minutes.

The left side was another matter altogether.

I could not get the buffer to budge with the small amount of leverage that I could get with the vice grips on the neck. So I jammed two nuts together on the top threads, only to discover that the rubber inside had disintegrated so that the buffer would turn freely. So I resorted to cutting the outside metal with a Dremel tool, and then griinding the aluminum inside the buffer, where the majority of the threads are, to release the buffer from the stud on the strut. About three hours on that side. See the second picture.

Anyway, this all had a happy ending. The clunk is gone. Anybody need a pair of nitrogen-filled accumulators?

Better hang on to them. You'll need them eventually. Usually a couple of months after you get rid of them!

Happy Motoring, Mark

ctaylor738 · #22 03-14-2007, 08:54 AM

George actually ended up sending me a complete pump unit that he had intended to use as a core. So I dismantled it, tested the pump, connected it into my pump unit and hooked it in its little cubby hole under the rear seat.

Tried the door lock from the dash switch. Success! The pump ran briefly and locked the doors. Unlock from the dash. Pump runs. Passenger door unlocks, but the driver's door does not - that is a known problem, though.

Try locking unlocking from outside. Doors, trunk, gas door all work. Looking good.

Back in the car, turn the ignition on. Pump begins to run continuously. Not good. I remove line and plug the outlet for the lumbar support. Pump stops running continuosly. Conclusion: lumbar bladder blown or other leak.

But now, with key on, the pump runs continuously, but differently, cycling bewtween suction and pressure. Not good. But interestingly, the reverse assists work and the locks still work. When these are used, the pump stops cycling attends to the request, then goes back to cycling. But why is it cycling?

I stop and write a long post on the Tech Support Forum and get an excellent answer back from wbrian63.

W140 Coupe Locking Pump Near Death

The pump is trying to "trim" the reserve pressure and vacuum tanks!

I plug both constant vacuum (p-) and constant pressure (p+) outlets which go to the respective tanks. Problem is no better. Fault is obviously internal to the pumps controls, which look like the motherboard of a PC connected to an airplane-like system of valves and switches.

I find the wiring diagram and find that there are two power leads to the unit - battery and key on. I disconnect the key-on power lead from the pump. Voila. No more cycling pump, but functioning locks and reverse assist, at the cost of no lumbar and rear headrest raising/lowering.

OK, I can live with that. The car is driveable without frying another pump motor, and the major PITA of no central locking is resolved. So now I can investigate the lumbar and cycling problem as time permits.

ctaylor738 · #23 04-27-2007, 08:32 AM

Last week the coupe got new tires (Kumho's from Tire Rack for $67 each). Then it went to JCP Motorsports in Alexandria for new tie rods, idler arm bushings, and a four-wheel alignment. What a difference! The various shakings and vibrations are gone and the car feels much more solid at speed.

Was also advised that new front stabilizer links are needed. This is a good DIY because the calipers and brake discs need to come off to get at the nuts on the steering knuckle. The arrangement is almost exactly like the setup on the rear of the 114's.

vinnie999 · #24 05-21-2007, 06:00 PM

Thanks for all the great info Chuck!!! I decided to try the buffer replacement on my 94 S500 but upon disassembly found the bushings bad instead of the buffers. There are no replacements offered but being a machinist I've never let that stand in the way before. I didnt think to take pictures until it was too late but it wasnt terribly hard to do. I removed the struts just like you described earlier, then using a high speed cutter very carefully removed the bead of weld that retains the bushings. The bushings are a ball and socket affair instead on what I was expecting and the metal sleeve in the center of the bushing has about a one inch ball in the center of it. After removing the socket pieces which are either plactic or teflon I was left with a straight hole 1 1/4" id x 1" wide. The od of the metal sleeve I removed from the old bushing was 3/4" od and 1/2" id (except for the ball made onto it). I dont have a lathe where I was doing the repair so using a bench grinder and plenty of coolant I removed the ball to make it a a straight 3/4" od by 1/2 id sleeve. I was thinking of using something just to make a new sleeve but was concerned that whatever I used wouldnt be hard enough which is why I ground the ball off of the original. I measured the channel in the control arm and it was 2" wide, so off to the rubber supply store. I purchased 4 tapered neoprene bushings 1 1/4"-1 3/8" od with a 3/4 id and 1"wide each. I inserted 1 bushing on either side on the strut eye and slid the steel sleeve through them and reassembled. The clunk is now gone and the parts cost twelve bucks instead of twelve hundred. There may better materials to use for the bushings but I've put over 1000 miles on the car since the repair and it's still fine. I also have an oil tube problem and thats next. I am kind of disappointed in the fact that this car only has 66k well documented miles on it and has these failures. I just sold my 86 560sel and aside from ac problems it was pretty much a trouble free car with over 185k.

ctaylor738 · #25 05-23-2007, 10:14 PM

The oil tubes are not a big deal. If I were to do it again, I would only replace the one(s) that blew out.

These cars are so heavy that they beat the suspension to death. But I do think that the comfort and conveniences they offer make them worth fixing.

ctaylor738 · #26 11-15-2007, 12:12 PM

I thought that I was going to be able to tackle the Job From Hell aka the Big One, the evaporator replacement in October, when Senior Management was on a cruise. I have a detailed 35-step plan with individual sub-steps so that I can label the parts. But I ended up pulling the gas tank out of my new(er) 380SL, and doing the brakes to get it driveable.

Since I did the rear suspension, the Coupe has been a daily driver without problems. But I did want to let you guys know that I still have it and intend to pursue the Big One.

cth350 · #27 11-15-2007, 06:04 PM

A friend of mine who's been driving an S320 since new was told the evaporator replacement would be 4 grand by the local dealer. He asked me for a recommendation and Jaimekomp recommended his favorite mechanic in NJ.

His advice was to throw in a can of leak sealer and recharge the system. That was August and so far, no problems. The mechanic is a dealer mechanic who set up his own shop, so one wonders why the dealer didn't recommend the same thing. Perhaps they want the practice?

-CTH

ctaylor738 · #28 11-16-2007, 01:56 PM

But unfortunately, this one is beyond the sealer stage. I had it charged in August with dye added and you could literally see the charge running out of the system in the condensate. It was losing 10% of its charge every 24 hours.

But the good news is that nothing besides the evaporator was leaking, and all of the AC controls behaved correctly when there was enough pressure to run the system.

It's interesting, though. On a warm day, at least half of the 1990's S-classes you see will have their windows down. And it's not because their owners enjoy the wind in their hair!