Switchblabe key 1992 (mechanical)

Hi,
My key would not flip closed except by forcing it and then it would not flip open except by prying it open. It pokes a hole in your pocket and scratches things when you keep it open all the time.
Fix:
Disassemble key:
Remove battery covery, batteries.
Find and remove small silver, "dovetail" shaped metal clip in cavity of key body. This holds the two halves of the key together.
Pry two halves of key body apart beginning near pivot. The two halves are connected by a flat electrical cable, fragile.
The key pivot will come off.
There is a clever torsion and compression spring inside the release push button. This must be preloaded in torsion upon assembly or the key won't flip open. Re-assemble carefully.
For me the mechanism worked fine at this point, I hope it does for you. I imagine it was dropped once and the torsion spring jumped from its locating notch.
If you have similar problem I hope this helps, if not message me and I'll try to fix it for you. No charge.
Dave McK.

 

Error codes for the Becker Mexico 14-15 series

Error Codes "E CODE"

"NO DISPLAY"
1 Input Power to the HEAD UNIT(dash mounted) is missing. Check with volt meter to test for 12 volts
2 Fuse of the HEAD UNIT(dash mounted) is open, Replace it with a 5 amp fuse
3 HEAD UNIT(dash mounted)is defective

"E1"
1 HEAD UNIT is defective

"E2"or "E3" (Without CD Changer)

1 Input Power to the RECEIVER UNIT (Trunk mounted) is missing, Check with volt meter to test for 12 volts
2 Fuse of the RECEIVER UNIT (Trunk mounted) is open, Replace it with 7.5 amp fuse.
3 The BUS CABLE (gray colored) that connects to HEAD UNIT(dash mounted) to the RECEIVER UNIT(trunk mounted) is not connected or is defective.
4 RECEIVER UNIT(trunk mounted) is defective.

"E2 or "E3" (With CD Changer)

1 Input power to RECEIVER UNIT (Trunk mounted) is missing, Use a voltmeter to test for 12 volts
2 Check the RECEIVER UNIT for an open fuse and replace with 7.5 amp
3 Input power to the CD CHANGER (Trunk mounted) is missing, check with volt meter to test 12 volts
4 BUS CABLE (gray colored) is defective or disconnected,
5 CD CHANGER is defective, Disconnect the CD CHANGER from the HEAD UNIT, if the E2 code disappears, Replace the CD CHANGER,
6 RECEIVER UNIT (Trunk mounted) is defective.

"E4"

1 RECEIVER UNIT (Trunk mounted) is defective.
2 CD CHANGER (Trunk mounted) is defective. Remove the CD CHANGER If the E4 code disappears, Replace the CD CHANGER

"E5"

1 RECEIVER UNIT (Trunk mounted) is def

 

I just wanted to say thanks for all this guys. You guys probably know more than any moron at my stealers anyday

 

I just wanted to say thanks for all this guys. You guys probably know more than any moron at my stealers anyday

Hello milbrath

Welcome to BW.

 

IF you need to run Instrument cluster function test. To do it start engine, then press small button in the center of clock adjusting knob (not the knob itself) for more then 5 seconds. You'll need something like a sharp pencil to do it.
The first test will appear on the outside temperature display. It will read something like 35.1, were 35 is gas in the tank in liters and 1 is the number of the test. To advance to the next step pull the clock knob and turn it clockwise.
There are 9 steps:
1. Gas in the tank in liters
2. Momentary fuel consumption 34.2 is 3.4 liters per hour 2 is step number
3. Engine oil pressure in bar 20.3 means 2.0 bar step 3
4. Engine rpm x 1000
5. Engine oil level 0.5 is OK, 1.5 not OK
6. Activation of the oil pressure, fuel consumption, and fuel tank gauges - needles in the first quarteer of the dial. Indicator 0.6 for step 6
7. Activation of the oil pressure, fuel consumption, and fuel tank gauges - needles in the second quarteer of the dial. Indicator 0.7 for step 7
8. Activation of the fuel consumption, and fuel tank gauges - needles in the third quarteer of the dial. Oil pressure gauge stays in the second quarter. Indicator 0.8 for step 8
9. Activation of the fuel tank gauge, needle in the fourth quarter of the dial, oil pressure remains in the second qurter, fuel consumption remains in the third quarter. Indicator 0.9 for step 9
Done
You need to verify oil pressure reading in step 3 and gauge in steps 6...9

I have an S320 från 1998 and I ran the test or I tryed to run it but i didn't get anything in the screen (see pic 2). I just got number twelve and a "U" in the "miles"-screen (see pic 1). In picture number 1 I just put the text there (12 u) so you can understand better.

 

For the OBD2 units.. here is a link to the Euro codes and their meaning

http://www.dntn.co.uk/keycode.htm

hope it helps

 

For the OBD2 units.. here is a link to the Euro codes and their meaning

http://www.dntn.co.uk/keycode.htm

hope it helps

But not a single one of the codes you linked began with 12. They all began with P.
I can't get the test to work properly.

 

great thread dudes. I printed them all out and start reading them tonight

 

I am a newbie here and that would definately help me out.

 

Very helpful V12 diagnostics tips. Thank You. I own a 1993 600SEL and have encountered similar issues. Current challenge I have is ASR and ABS lights. I have new battery, new alternator, new ground cables and extra ground cable at the battery. All trying to find out why the ASR & ABS lights intermittently come on. Brake pads are 6 months old and all with new pad sensors, properly installed. Front wheel speed sensors checked and cleaned. All ASR and ABS connections checked. No codes present in ASR / ABS module. Only present code that will not go away is a right 02 sensor heater inop, with new Bosch 02 sensors only 3 months old. I may have to check the wiring for the 02sensors. Engine wiring harness seems ok and EAs work ok and Mass Air Flows recently cleaned.
Any ideas?

Thanks again.
Bill Mercer

 

The problem is typically with the front ABS sensor wiring (intermittent signal). This coaxial wire has to turn with the wheel and flexes with the suspension travel. For LHD cars, the right wheel sensor gets the majority of abuse, due to potholes, curbs & etc.

As soon as there is lack of signal from any one wheel sensor, both the ASR & ABS light will light.



The typical one that goes is the right wheel sensor for LHD cars.

 

First check to see all your tyres are the same size..
then check the rotation on each wheel separately.. that is with ignition on and rotate each wheel and see the light comes on after half a turn..
then the steering sensor..
jack the front up and turn left to right..then right to left....
then..there are gearbox issues that will affect the asr and abs lights ..
you need to try to pull the codes for the gearbox....

 

Addendum to the closing assist system write-up.

i. Making an access cut-out in the pump housing.

Bob B. contacted me with an interesting modification that he made to his pump. After removing the pump’s cover to make the shut-off pressure adjustment to his Bosch pump, he actually cut a flap in the side of the pump cover right where the shut-off switch is located. Now future adjustments can be made without needing to disconnect all the air lines. Not a bad idea. And by the way, reducing the shut-off pressure has completely restored operation to his closing assist system. Here’s a picture of his handiwork. Note that this may be practical only for the Bosch closing assist pump. I’m not as familiar with the Hella pump.

 

Hello everybody

I'm new to this forum.Just joint.I had own a 280 SE 126 for close to seven years now, imported used from England. Done about 350K km myself plus 220K km by the previous owner.Since that car is real nice, I would like to have another Merc. S320 W140 model year 1994 or 1995. I can't afford a brand new one.In my country - Malaysia, Road tax for anything bigger than 3.5 liter is too high for me. This s320 and 280 is going cheap because not many willing to fork out so much to pay for the road tax and maintenance. Any advise ?

 

Very helpful V12 diagnostics tips. Thank You. I own a 1993 600SEL and have encountered similar issues. Current challenge I have is ASR and ABS lights. I have new battery, new alternator, new ground cables and extra ground cable at the battery. All trying to find out why the ASR & ABS lights intermittently come on. Brake pads are 6 months old and all with new pad sensors, properly installed. Front wheel speed sensors checked and cleaned. All ASR and ABS connections checked. No codes present in ASR / ABS module. Only present code that will not go away is a right 02 sensor heater inop, with new Bosch 02 sensors only 3 months old. I may have to check the wiring for the 02sensors. Engine wiring harness seems ok and EAs work ok and Mass Air Flows recently cleaned.
Any ideas?

Thanks again.
Bill Mercer

You are guys so helpfull for newbies like me.
1994-500S
I have a similer problem like Bill, but with a clear signs i guess. My speed indicator
not reading steadly .. like shaking betwen 80 and 90 for example. ASR/ABS lights up soon after.Moreover, I can clearly hear a rubbing noise coming out of the front left wheel.
I removed the front wheels speed sensors and found so dirty(speicaly left side), clean it and the noise disapper , pointer and ASR/ABS were all fine for few weeks . Then it all came back again now ... remove them found clean , clean it again but still the same problem .. any Ideas ?

 

Changing the fuel filter

Changing the W140 fuel filter

It’s about a 15 minute job to change your fuel filter once you have your car lifted. My car is a 1997 model S600. Most other W140’s are probably very similar if not identical. I have a low-rise lift making the job really easy, but putting the rear up on ramps should be enough. Do not work under your car until you have it safely lifted (ramps, jack stands, or lift). Do not work with only a jack supporting the car! You need to crawl all the way underneath the rear to access the fuel filter.

The fuel filter is located under and just aft of the rear passenger seat. It is concealed along with the fuel pump under a protective plastic cover. This pic shows the cover and the location of the three nuts that you must remove to remove the cover. Simply remove the nuts and work the cover off of the studs.

The fuel filter and fuel pump are clamped into a bracket together, and the bracket is suspended from the bottom of the car using rubber grommets. Check the condition of the grommets. If they are in bad shape, replace them. You may need to release the bracket from the grommets to make access easier.

First, clamp off the fuel lines on either side of the filter. Loosen the screw that holds the filter in the bracket, and loosen the hose clamps holding the fuel lines on the filter. Before you remove the filter, note the direction of fuel flow indicated by the arrow on the filter. Be sure to install the new filter with the arrow pointing in the same direction. Have a drain pan ready, and pull the lines off the old filter. About 1-2 cups of fuel will spill out. Remove the old filter, and put the new one in place (arrow in the proper direction). Put the fuel lines on the new filter, and tighten the hose clamps. If the clamps are in bad shape, replace them. You definitely don‘t want a fuel line popping off. Tighten the screw to clamp the filter in place. Replace the cover and tighten the nuts holding it in place. That’s it.

This DIY write-up should be available on www.v12uberalles.com shortly.

Brett

 

S600 spark plug change

This write-up documents changing the plugs in my car, a 1997 S600. 1995 and earlier model years with distributor ignition will not have the ignition coils shown in the pics at each cylinder. Changing the spark plugs in the V12 is pretty straightforward except for cylinder #12, which is buried under the tray for the wiring harnesses. It took me about 45 min to do #12 and another 1 hr to do the other 11.

If you’re more creative than I was with flexible extensions and socket universal joints, you may be able to reach #12 without flipping up the wiring harness tray as I am about to describe. #12 is under the tray as shown in this pic. # 6 is also partially blocked, but you can reach it with two shorter extensions and a U-joint.

Begin by removing the climate control intake plenum (same thing you would do to change the pollen filter). First, disconnect the vacuum line to the flap on the passenger side, and then remove 6 screws shown in the pic.

Under the driver’s side of the plenum, twist and release the climate control’s air temp sensor.

And, finally disconnect the electrical connector for the wires to the smog sensor, and lift the intake plenum out of the car.

Now, from the driver’s side flip up the wiring harness tray that is behind the firewall. It is hinged and easily lifts up. Remove the three 8 mm hex screws holding the forward harness tray (the one above #12) in place.

Lift the tray, and you’ll see that you now have easy access to #12. The tray is split in the middle so you can just lift this side of it enough without having to undo the entire tray all the way across the engine compartment.

Change out #12, put the tray back in place, and reinstall the climate control plenum. Then move on to the other 11 plugs.

Changing each plug, requires removal of the ignition coil. To do this, disconnect the coil’s electrical connector, unclip the metal clip that holds the coil, and grasp the coil by the top and wiggle it out of the spark plug tube. You then need to remove the coil’s retaining clip. Just squeeze the open end of the clip, and work it off of the intake manifold. You’ll see.

Here’s the removal of the ignition coil.

I used an air duster can to blow any junk out of the spark plug tube. An air compressor hose would be better. The ignition coils have rubber gaskets to prevent stuff from falling into the tube, but better to be sure. You don’t want any grit falling into the cylinder.

Using a spark plug socket on the end of a long extension, remove the old plug and install the new one. Torque the new spark plug to the appropriate value. My owner’s manual said 20-30 Nm. Replace the coil retaining clip and the ignition coil, and reconnect the electrical connector.

After 8 are done, it’s kind of annoying to think that the V8 guys are kicking back enjoying a beer by now. Hang in there. I know your back is killing you. Only 4 more to go. When you’re done, check your work. I actually left a coil unconnected and didn’t find it until I had started the car and experienced a shaking engine from the misfire. Re-checking revealed the disconnected coil.

 

Addendum to the closing assist write-up

k. Another failure mode of the Bosch pressure shut-off switch. Guide fins breaking off of the white plunger.

Thanks to Simon C. for describing another failure of the Bosch pressure switch. Simon’s pump was timing out regularly. Upon closely watching the white plunger of the shut-off switch, he noticed (like Posix did in section e) that the plunger wasn’t moving at all. He tried pulling the plunger with needle-nose pliers, but it still would not move, so he resorted to disassembling the pressure shut-off diaphragm. The culprit turned out to be broken fins on the white plunger. The plunger has several tiny fins around its perimeter, which guide the plunger by mating to slots in the black housing. A couple of these fins had broken off and jammed the plunger. In his case, the rubber diaphragm inside the cylinder was fine. Simon simply removed the plunger and cleaned out the debris. Upon reassembly and adjustment of the shut-off pressure, his pump was back to normal operation. As he describes, the shut-off switch diaphragm can be separated into two parts and repaired without desoldering the electrical part of the switch from the circuit board. First, remove only one screw holding the rear section of the black plastic housing to the circuit board.

Second, release all the small clips around the circumference of the black housing to separate the rear of the diaphragm, leaving the section encasing the white plunger connected to the circuit board. You can now remove the white plunger and the rubber diaphragm to inspect them for damage.

 

The quality of this knowledge base is incredible!

 

First a quick history lesson on the MB hydraulic suspension.

Accumulators or Spheres as there sometimes called are the "springs" of most of the 140's rear suspension. The ride leveling system was installed on all 500's and 600's, optional on 420's and not installed in 300/320's - at least in the States. I've heard second hand that it was optional on 500's for most other markets. There are two different systems installed on these cars. The basic is a rear ride height control only and this system has no center console control switch- the system is transparent to the driver. This system has two accumulators. The other system has three accumulators and can be identified by a small switch on the enter console with a pictogram of a shock absorber. This system is called ADS or ADSII (Adaptive Damping System) depending on the model year. Basically this allows you to firm the suspension on all four corners. This system also controls the oil flow in and out of the front shock as well. This article deals with the two accumulator system because that's what I own- a 1997 S500 with ride height control. If you have ADS, the procedure is substantially the same- your just replacing three accumulators.

After about 80,000 miles the ride in these cars starts to deteriorate. Bumps that once went unnoticed now start to jar your hind teeth. When you notice that your starting to avoid manhole covers- it's time. What happens is the Nitrogen pre-charge starts to leak out. In a new accumulator, the pre-charge is set to 155bar- that's 2279psi! When the car hits a bump- hyd fluid is forced out of the shock and into the accumulator via a hydraulic line. This compresses the nitrogen gas inside the sphere- as the suspension expands on the back side of the bump the pressure inside the accumulator forces the fluid back into the shock. As the accumulator ages, the pre-charge leaks out and the void is filled with incompressible hydraulic fluid. This is where the ride stiffens up. When all the pre-charge is gone you basically have a hydraulic lock and the suspension stops working. My mechanic says he's seen cars come in where you can't compress the rear suspension even by jumping on it. It would be funny except that if you let your suspension go that far you risk damaging the hydraulic shocks- there about $870.00 a piece to replace. The accumulators are about $100.00 a piece to replace. You do the math.

In the two accumulator system, they're located approximately under the rear seat- tucked up and bolted to the underside of the floorpan. The driver's side (left-hand drive) accumulator is obscured by the exhaust system - not a problem. On cars equipped with xenon headlights, the right accumulator is blocked by the headlight level control. Simply unplug the electrical connector and remove the controller. Here's a few drawings from ALLDATADIY.com located at the bottom of the text.



On to the messy part!


Regarding the accumulators, the job is pretty easy, if not messy. Jack up the rear. If you don't have two floor jacks, try this- chalk the front tires and use the supplied tire changing jack to lift the car. Place a jack stand under the lift point (rubber doughnut) and set car on the stand. Move to the other side and repeat. Not ideal but it works. Please be careful! You might want to even "chalk" the car jack as it contacts the ground at an angle and on a slippery garage floor- well, it could slip. Bleed off as much pressure as you can using the nipple on the level control valve. I stuck some clear plastic tubing on to the nipple and cracked it open to let the hyd fluid and foam escape (brown foam means your accumulators are indeed bad). Once this is done you can remove the doughnuts or hangers that attach the exhaust system to the under side of the car. I think there were two on either side of the muffler and one just aft of the cats. I just unbolted them from the floor pan. This allows the system to hang down just enough to remove the driver's side accumulator. To remove the accumulator, simply remove the two hyd lines that attach to the accumulator and then remove the three mounting bolts. Prepare for an unholy mess at this point. Despite all my best efforts and warnings from other people I still dropped about a quart and a half of oil on the garage floor. Both sides require some finagling to get the accumulators out of their hiding spots but they will come. Some people have had trouble removing the hyd lines from the accumulators. This seems to be more of a problem for cars located in areas that use road salt. A good flare nut wrench is what is required here. This wrench looks like a standard box end except it has a small gap at the end that will allow you to slide the wrench over the hydraulic line. This wrench will help prevent damage to the soft metal nuts that hold the hydraulic lines to the accumulators. It should be noted that I was able to remove the lines with a standard wrench with no problems. Also be very careful not to cross thread the nuts onto the new accumulators. The hydraulic lines are stiff and if you don't line them up perfectly, you can cross thread the nut. This proved to be the most difficult part of the task. I had one on the right that would absolutely refuse to thread correctly. Patients, a beer, and another whack at it did the job.

Once both accumulators have been replaced I followed ALLDATADIY.com's instructions for filling and bleeding the system. Here's a reprint:

FILLING:

Pour oil into the oil reservoir

Only reuse clean oil

Set level controller lever to "Fill" position (F)
(loosen the ride height linkage- this will allow you to move the lever between FILL and EMPTY)
CAUTION
Risk of accident due to the vehicle starting off automatically when engine is running
CAUTION
Risk of injury due to bruising or burns when intervening while starting the engine or when the engine is running

Start engine, allow to run at moderate speed for approx. 60 seconds

The system bleeds itself automatically

Switch off engine

CAUTION
Ensure that there is sufficient oil in the oil reservoir
The pump must not suck in air under any circumstances

Set level controller lever (arrow) to position "Empty (L)"
After approx. 60 seconds, attach connecting rod or connecting linkage (7) to level control lever (arrows) NOTE:

Replace self-locking bolts and nuts
Place vehicle on its wheels and press down firmly several times.
The vehicle level adjusts itself
Check and correct oil level in oil reservoir

Be careful not to over fill the reservoir. I got a little too concerned about running the pump dry that I overfilled the system. Remember that when you move the lever to FILL, your filling the accumulators and raising the suspension. This will lower the reservoir. When I saw the low level ( lever still on FILL) I topped it off. Oops! When I moved the lever to EMPTY (engine off) The accumulators purged their oil and it flowed back into the reservoir. I heard this strange squirting sound. There was oil all over my garage wall. It had squirted out the overflow which thankfully had been pointing toward the front of the car and not into the engine compartment. Nothing bad happens if you overfill the reservoir- it's just messy and embarrassing.
Good luck!
Paul

Hey guys, i just ordered my new rear hydraulic shocks for my 95 S500 from autohausaz.com, is there such a thing as a suspension filter for the hydraulic suspension oil? here is a link:
https://www.autohausaz.com/search/p...elid=1195747@S420&year=1995&cid=27@Suspension System&gid=7438@Suspension Filter
if it's true where is this filter?

 

yes thats the one in the reservoir at the font.. check my gallery for better pics.. also the third sphere on the rear, could be for the locking diff, if you have one.. a button with snowchains on a tyre will tell you you have.. otherwise the third sphere is at the front behind one of the wings i am told..

 

1997 S600 Bosch alternator bearing replacement

1997 S600 Bosch alternator bearing replacement

This article describes replacement of the alternator bearings in my 1997 S600 sedan. Keep in mind that different model years may be different. My alternator had been making quite a racket for some time. Electrically it was fine, so I figured it was just the bearings that were bad. If it was just bearings, I wasn’t inclined to pay for a completely new (or rebuilt) one. I was right. With the new bearings, the alternator runs quiet and smooth, now. This Range Rover web site covers bearing replacement in the Range Rover Bosch alternator.

Bosch_repair

I found my W140’s alternator was nearly identical with the exception of a larger front bearing.

Special tools for the job:
1. Gear/bearing puller (a generic puller is fine)
2. Impact screwdriver
3. 10 mm 1/2 in drive triple square driver (I bought a set of 4 SK brand triple square drivers.)
4. 22 mm tool to turn the pulley nut. My father-in-law had access to a welder so we made one using an old wrench and a 22 mm 1/2 in drive socket. The official Bosch alternator pulley nut tool looks like a deep well crowfoot socket, only the “crowfoot” is a complete socket going all the way around the nut. Here are the triple square bit and the pulley nut wrench that we made.

We ground down the triple square bit a little and drilled out the socket so that the bit would fit through the socket. See the part about pulley removal to see a pic. Alternatively, an air impact wrench may work to remove and install the pulley nut without messing with special tools.

Removal of the alternator is not simple. It seems nothing is in the V12’s engine compartment. You must remove the front anti-roll bar, and you must drain the coolant and then remove the lower coolant hose.

1. I put the front wheels on ramps to remove the anti-roll bar. It seemed there was a little tension on the anti-roll bar when the wheels were allowed to hang. Getting the bar off the end links (and reinstalling on the end links) was easier with the suspension compressed with the wheels on ramps. Do not work under your car without the car properly supported (lift, jack stands, or ramps)!

2. Disconnect the ground (negative) terminal on the battery. You will need your radio code to reactivate the radio, and you will have to reprogram the express function of the windows when you’re done.

3. Remove the ADS sensor attached to the right side of the bar. Of course, if you don’t have ADS, you won’t have this. Disconnect the electrical connector and remove the U-bolt and the two nuts holding the bracket to the studs. (Everything is so clean because I took these pics during reassembly.) Note the flat on the bar that locates the sensor arm.

4. Remove the 2 nuts attaching the sway bar links at the end of the bar. These are ball joints, and you will likely have to counterhold the stud with a 6 mm allen while turning the nut. I used a crowfoot on the nut and let the counterholding bar lever itself against something solid. These nuts are self-locking and should be replaced with brand new ones. They get 80 Nm of torque.

5. Remove the 4 nuts (2 on each bracket) that attach the bar to the frame, and remove the bar. These nuts are also self-locking and should be replaced with new ones. These nuts get 20 Nm.

6. Disconnect the 2 wires on the backside of the alternator. You have to crawl all the way underneath and look toward the front of the car above the cross member to see the back of the alternator. I used a long extension to reach forward to the alternator.

7. Remove the lower coolant hose. Here’s why you need to remove it. It blocks removal of the bolts. In fact, there is a nub molded into the hose to keep the alternator mounting bolt from rubbing through the hose.

You can simply separate the hose from the radiator and let it drain, or you can drain from the radiator stopcock on the left side of the radiator and then remove the hose. About 2.5 gallons will drain out. Have a big enough container and make sure it is clean if you will reuse the coolant.. To drain from the stopcock, pop out the panel on the left side of the bumper (where the outside temperature probe is mounted). You will find the stopcock right behind the panel. Put a clean hose on the nipple, and open the stopcock with a screwdriver.

Drain completely, and then remove the hose clamps on the hose and remove the hose from the radiator and the water pump.

8. Slacken the belt and remove it from the alternator pulley. No picture here since I really couldn’t get a good one. It’s a tight squeeze. Working from underneath on the left side of the engine, put a 15 mm socket with a breaker bar on the nut in the middle of the tensioner pulley, which is just to the left side of the crankshaft pulley. I had to push the fan shroud around a bit to work the socket onto the bolt. Rotate the tensioner to release tension, and remove the belt from one of the pulleys. Then work the belt off the alternator.

9. Remove the 2 alternator mounting bolts and remove the alternator. The bolts are 15 mm.

 

10. Remove the 22 mm pulley nut. With the alternator out of the car, try your impact wrench on the pulley nut. If you don’t have one, get your special tools out. You may need to get creative with bracing one wrench and turning the other. The nut is spun on there pretty tight. I don’t know what the recommended torque is.

11. Remove the plastic backing. Remove three small screws and one large screw. Then release three clips around the perimeter, and simply pry the cover off.

12. Remove the voltage regulator. Here are the numbers on my alternator’s regulator.

The regulator is held in by 2 phillips screws. Remove them and remove the regulator. The brushes are spring loaded. Note how much length is left. If they are almost worn completely down, you should try to replace the regulator. I’m not sure if you can buy these regulators easily. You may have to see if a rebuilding shop will sell you just the regulator.

13. Split the case. Mark the case halves so that you can put it back together correctly. Remove the 4 bolts around the perimeter, and pry the case halves apart. The front half will come out with the rotor attached.

14. Recover the rear bearing cup. The rear bearing has a plastic cup on it. It may have stuck in the rear case half. Find it, clean it, and don’t lose it.

15. Pull the rear bearing off the shaft. Do not use pressing force on the plastic end of the shaft. What looks like the end of the shaft is actually a plastic sleeve formed over the shaft, that holds the electric contacts (the copper slip rings) for the voltage regulator brushes. Guide the tip of the puller into the center of the hole so that it contacts the metal shaft directly.

Note the bearing markings. The rear bearing is a standard size 6203 bearing (40 mm outer diameter x 17 mm inner diameter x 12 mm width). You can find this bearing online at many bearing sellers. Make sure to buy the 6203 2RS (2 rubber seal) bearing. You can go with the inexpensive Chinese or Japanese import bearing, which costs about $6, or you can go with a name brand one for 7-8 times more (SKF or ***). I decided to try the cheap Chinese made bearing. If the bearing goes bad in short order, I will consider getting the more expensive bearing next time.

16. Remove the rotor from the front housing. First remove the 4 screws in the face of the alternator. These can be corroded and stuck pretty good. I used a hand impact screwdriver to remove my screws. I replaced them with new stainless steel screws and used a little anti-seize paste when reassembling. I then used a hammer to drive the rotor with the front bearing attached out of the housing.

17. Pull the front bearing and thrust washer off the shaft. Note the orientation of the thrust washer. It has a shoulder on the side that faces the bearing. The front bearing is a big bearing that is apparently an oddball size (52 mm outer diameter x 17 mm inner diameter x 17 mm width). I looked and looked and could not find this bearing from any online bearing sellers. I called Nachi, the maker of the bearing that came out of the alternator, and the response was that was not a bearing that they import to the US. I then called a local alternator rebuilder who said he had the proper size bearing and would sell me one for $45. Here’s the bearing:

It has almost no markings on it, so I can’t give any advice on where the average joe can find one. It’s probably a cheap import that cost him about $10, if that much, but I didn’t mind paying the mark up given the trouble I had trying to find one. I was so excited to get it, I didn’t even think to ask his source. (note: I have since located this bearing online. If you google "alternator bearing" you will find sellers of this bearing. Apparently, it is a bearing specific to automotive alternator applications. I have seen the bearing listed under these part numbers: B17-99 (the number on the bearing in the pic above) and also B3043-2RDA. I bought one from this site, http://bearingsdirect.com/products/index.php?action=category&id=56 .)

18. Reassemble the alternator. Putting it back together is straightforward. Install the rear bearing on the shaft. I used a deep well socket as a drift and drove it on lightly with a hammer. Press the new front bearing into the front case. I used a block of wood and a hammer with a squirt of WD-40 for lubrication to seat the bearing. With a little more WD-40 on the shaft, the shaft slid right onto the front bearing. Don’t forget the bearing retainer plate, which has to go on the shaft before the front bearing. Install the 4 bearing retainer screws in the front of the case. Replace the plastic rear bearing cup in the rear case, and mate the case halves with the 4 bolts. Reinstall the voltage regulator, and replace the rear plastic cover. Finally, slip the thrust washer back on the front of the shaft (shoulder toward the bearing), and reinstall the pulley using the tools.

19. Reinstall the alternator in reverse order. Replace the coolant hose and anti-roll bar. Reconnect your battery. Refill your coolant reservoir. Start it up, and top off the coolant as necessary with 1:1 distilled water to MB coolant.

My total cost was around $70 (bearings + new screws and nuts). If that front bearing were readily available, it would have been much cheaper.

Brett

 

Let me know if I can be of assist? Nails and everything else is Caked w/ dat Hydrocarbon stuff..... keyboard is full of oil grime too....I here for yall, just ask! Gunner "Semper Fi"

 

a very helpful thread! I'm going to change my Mercedes ignition coil next week. I'm planning to do it myself. Hoping to do it right and there would be no problem.