-W126 cruise control: the amplifier under the dash dies. It's by the parking brake pedal and is held in by a 10mm bolt. Either take it apart & re-solder connections OR send it to be rebuilt (about $150-200). Can't do both-- if you re-solder, they will NOT accept it as a core.. decide first!

-W126 trunk leaks: If it's leaking from a "hidden" spot into the trunk wells, check three areas: 1)tail light can leak water in from the seal 2)antenna grommet can be bad and will leak 3)rear window gasket can leak in bottom corner. Hope it's not #3 as this means there is rust under the gasket in this area (common) and needs to be cut out & fixed. It's worse than you can see as it's hidden by the gasket. Get in trunk & have someone spray with hose to find the leak.

-W126 rear seat: easy to remove- find two tabs (may be colored red) at bottom of rear seat cushion. Push both tabs toward each other, lift front edge of seat and pull out. Seat back comes out by removing a few 10mm bolts at the bottom, then pull bottom away from car and lift straight up. WATCH out that the metal tabs on the bottom don't scratch the car on the way out!

-W126 erratic fuel gauge OR low fuel light not working (diesel): Remove rear seat, remove large plastic cap and disconnect wiring for fuel sender. Use large socket (46mm?) to unscrew fuel sender. Use rag as it is full of fuel and will drip! Take off nut at bottom and remove metal tube. Clean CAREFULLY so you don't break any of the fine wires. I use brake cleaner and it works fine. Reassemble and fuel gauge will work. If not, replace.

-W126 back end of car steers itself: your sub-frame mounts are old. They can be easily replaced by making a tool out of threaded rod and some bolts, and using a couple of shop jacks. Spray the bolts 2 DAYS BEFORE with PB blaster and the job will be 100x easier! Search forums for more info on replacement

-W126 fuse for trunk light and memory seats keeps blowing: the wiring harness near the trunk hinge flexes all the time, and the wires have shorted. Pull the wires and electrical tape them, and you'll be fine.

-W126 window won't move, but motor runs: search forums for my post on "sliding jaw". This can be replaced for $5 and does not require any rivets if you use a bolt & nut like I did. Need to take off door panel, but it's an easy job otherwise. MB window regulators and motors almost NEVER fail.

-W126 voltage regulator: Look at back of alternator, remove two flat screws with stubby screwdriver. Pull out (comes out at an angle, doesn't pull straight out) and look at the length of the brushes (two rectangular rods with curved tips). 1" = brand new, 1/4"=dead on roadside. Judge how bad yours are and replace. They're $15 and well worth it. Even if you don't replace it, buy a spare for the trunk.
 

-W126 fuses. Replace them ALL before troubleshooting electrical problems. They look good but are NOT! I've had them fall apart in my hands even though they looked fine when in the fuse box. They're cheap -- buy a set and replace them all NOW and you'll be fine for 10 years!

-W126 front end clunk:
Could be a few things, but the tie rod ends and guide rod mounts are very common.

-W126 rear end clunk:
Check the sway bar links, they make lots of noise!

-W126 locked out of trunk: if the trunk linkage becomes loose & sloppy, you can't open it by pushing the button. Take a 2x4 about a foot long and hold it so one tip is on the trunk button. Whack the other tip with a hammer (seriously). The trunk should pop open. Make SURE the lock is unlocked first (you can lock & unlock the drivers door to make sure it is in the unlocked position). This won't work if something else is wrong with your trunk. Now pull off the top plastic cover and pull back the carpet. You can adjust the linkage from here. Make sure it works before closing the trunk!!

-W126 rear brakes: Make SURE you keep on top of the pad thickness. Once you're down to about 20% pad or less, the pads will cock themselves in the caliper diagonally. Then the caliper seizes. You will know this happened when you pull the pads and can't push the piston back into the caliper. It's time for a rebuilt caliper at this point. I'd change the rear pads (they're cheap and last for years!) when they're down to 35-40% just to be safe.

-W126 parking brake light stays on: There was a recall for the parking brake cable on this car. It involves removing the entire cable from the pedal to the rear brakes, including a ton of labor. Here's the easy fix: Put a wire tie around the parking brake pedal arm (near the top) and clip one end of a spring (from Home Depot) to it. Clip the other end under the dash to keep the pedal pulled up. Everything works as normal, but the little bit of slack in the pedal is eliminated, so the light will stay off.

-W126 dripping ATF: Most likely this is the ATF lines going to the radiator (transmission cooler). Replace these lines if they're dripping -- you just need a crow's foot wrench. You will know they are leaking if there is any ATF on the outside. You can find these easily by looking at the bottom of your radiator (look from under the car) and find two hoses that look like they have a "spring" covering the outside. It looks like a hose with a piece of wire wrapped around in a coil-like shape. You'll see what I mean.

-W126 hood pad: Buy a new hood pad but be CAREFUL how you install the new one. Search the forums -- there is a special 3M glue and you MUST scrape off ALL the old gunk first. If not, you'll be doing the job again in 2 weeks. Make sure to do it right the first time!

-W126 battery: The MB battery is made by Interstate and this is the best battery for the car. Try an Interstate before buying anything else for this car!

-W126 tires: Many opinions here, but Michelins have always been EXCELLENT for me on a number of these cars. One tire expert told me to remember the phrase "Michelins on Mercedes" because that's all they recommend after years of being in the business.

-Clunking from front end going over bumps: Check your brake support bushings (search forums for info). These are common problem areas on the W126. If they haven't been replaced, you will be changing them for sure.

-W126 windows or seats not working: The switch is dirty. Clean it out with contact cleaner or similar (TV tuner cleaner from Radio Shack works also). Most times the switch is just dirty. Keep working the switch back & forth while cleaning.

-W126 radio scratchy noise in some speakers: The fader (roller dial in the center console) corrodes a bit. Roll it back and forth as far as you can in each direction. I do this about every 3 months and the problem never reappears.

-W126 wipers: Use the original MB wipers (or buy a set if you have aftermarket blades). Some members have had great experiences with Anco blades, but I find the MB ones to work perfectly. You only replace the rubber in these blades (search forums for instructions on swapping blade rubber) and keep using the same blade "frame".

-W126 smearing windshield: After trying a ton of things (bending wiper arms, new wiper blades, scrubbing windshield w/glass stripper, etc, etc.) I found a solution. Put about 6 drops of dishwashing soap into the washer reservoir with each gallon of washer fluid. Use a "degreasing" detergent like Dawn or one that says it "cuts grease" on the label. Works perfectly (don't worry, there are no suds with this little soap). Keeps my nozzles from clogging and keeps the windshield clean.

-W126 stereo installation: Do NOT screw an amp to the rear wall of the trunk like you can do in many other cars. The fuel tank stands up (rather than being under the trunk) and is directly behind that wall. Diesel+amp screws=fuel smell in trunk. Gas+amp screws=BOOM!

-W126 rim care: These wheels are PAINTED silver, they are not clear coated "aluminum rims" like on other cars. So treat them like you would the rest of the paint on your car -- don't spray or use anything on the rims you wouldn't feel comfortable using on the hood! I have found a 1/2 bottle of full strength Simple Green and a brush will get off 90% of the dirt. Spray GENEROUSLY on cold rims and brush. Spray again and wait 5-10mins, then hose off. If they don't look significantly better at this point, nothing will help much and you're better off repainting them.

-W126 tire "bouncing" at highway speed: You are driving down the road and feel a wheel "bouncing" off the ground back and forth. Steering shakes and it's really scary. Slowing down makes it go away. The problem is 99% wheel balance. These cars are sensitive to wheel balance and will behave like this until the wheels are balance properly. Get someone with a Hunter wheel balancer -- there is a special model of Hunter that works REALLY well (someone tell me which one is best). Or try someplace that specializes in Porsche racing, high performance MB/BMW, etc, etc. Or try calling around to MB/BMW/Jag dealers to see if they have one.

-W126 What color diesel W126 should I buy?: Here's a tip I heard somewhere -- "Buy a color your grand kids like because they'll most likely be driving the car for a good portion of their life".

-W126 Bulb out indicator is on, but all bulbs are working!?!?!: Check the two bulbs that light up your rear license plate. They are on the same circuit and will set off the indicator. You never notice them, but if they are burned out, the indicator will come on. Also check the taillights, as there are two tiny "marker lights" in the outboard corners of the car (ie: furthest away from the license plate). Look at both taillights when on and see if they look different (one has a light where the other doesn't)

-W126 shocks:
You cannot use the "bounce test" on these cars. Unless the shocks are completely blown out they will not bounce. But the ride will be gone long before that. Check the shocks for leaks, if they are leaking replace. Also 100k-150k is about all they are good for. Bilsteins are the best shocks to use.