1. The OVP, if I recall at least, is on the driver's side around the fuse box, it should look like the picture in this link:
KAEHLER Overload Relay,W0133-1618613 - PeachParts

2. The modulator is on the driver's side on the side of the transmission, there will be a round thing part way down the trans, that's the modulator. There are many pictures online of what they look like.

3. Sounds like your car needs fuel filters and/or the tank strainer cleaned. I also suggest a diesel purge in the near future to help ensure everything is clear of junk that's been flowing around in the fuel system. Start there, if that doesn't work, you may be running into the famous OM606 fuel leaks. The IP delivery valve seals enjoy spewing diesel after a while, as do the brown "hard" fuel lines running to and from the IP. Look for air bubbles or debris in the semi-clear lines under the intake manifold.

4. This may be caused by the 94-95 Mercedes wiring harness rot. Look for the coolant temp sensor on the top of the motor near the end of the upper radiator hose, this has some wires going into it that originate from the harness, if your wiring is bare or the insulation is crumbling, then there's a good chance you need a new harness. The front fans on your car won't be triggered into high speed operation unless the temp reaches/exceeds 107c. They should operate on low speed with the AC running if the R134a in the system reaches a certain temp, but I'm not sure what that is. Your engine temps, however, are perfectly fine and nothing to be worried about, my 606 runs a little warmer than my 617 as well. If you need the fans to kick on more often, there's something called the Cool Harness available for use 124 guys that engages the fans at a much lower temperature.

Hey Guys,

So i have not been able to see the trans modulator. Do I have to remove the air Intake manifolds? Do I have to make any adjustments to the modulator when I change it? or do I just put the new modulator in?

I also have not been able to locate the OVP relay either.


Can you guys help out.

The OVP relay is behind the battery, you remove the big plastic cover that clips into the windshield wiper tray thing and you will be greeted by

1 expensive looking piece = ABS controller
2 ELR controller = Idle speed control
3 EGR controller = EGR and manifold flap control
4 KLIMA relay = AC control relay
5 OVP relay with two fuses on top

I would suggest that you remove the battery and clean out any dirt and leaves from that place, clean the drain(s) and test them too that water actually drains to the ground and does not pool up. Also check if any acid spillage has eaten away some wiring.

For the driving clunk - get under your car and check the driveshaft front flex disc, its a SOFT type with bosses that tear off from the main meaty rubber which then cause clunky shifts. Also check the D/S center bearing and shift lever bushings.

The transmission modulator is also seen while under the car, its about 2 inches wide and has a single vacuum line coming to it, it is found on the driver side of the transmission.

For the front fans, you can test them for high speed by disconnecting the front coolant temp sensor plug when the engine is running, the fans should run high speed and create a loud roar (those fans are quite powerful), the slow speed is wired through a resistor behind the left headlamp, to test the slow speed, unplug the wires of the AC high pressure switch and connect together, the fans should turn slow, if not check for current at the resistor with a test lamp, if one side shows current yet the fans dont run slow but run fast when the high speed sensor is disconnected you need a new resistor (the usual cause is burnt wiring which also welds the connection nut to the resistor post. Best replaced with left headlamp removed from car. The power fuses to the fans are not in the fuse box but on top of each of the relays that controls the fans, high speed relay is fused with a 30A green fuse while the low speed is originally fused with a blue 15A one but MB recommends that you upgrade to 20A as the fans can easily blow the 15A fuse.

If the wiring harness is shot, you can pay for a new one from MB ($$$$$$$) or make a new one with your old connectors, the wiring is very simple and straightforward once you take it out.

It is also highly recommended by everyone owning a W124 to replace the original corroded bullet fuses with copper ceramic type, They can cause some strange goofball issues.

Its a pretty decent car you got for $1300/- though.

__________________
2012 BMW X5 (Beef + Granite suspension model)

1995 E300D - The original humming machine (consumed by Flood 2017)
2000 E320 - The evolution (consumed by flood 2017)

ok thank you for the post.

1. I found the OVP and the Fuse is ok. Not sure if it is the OVP, or if I should check something else. Where is the sensor located?

2. I checked the drive shaft and there is minimal play, but a little clunk is heard from the center bearing area. I could not see in there because of the cover and exhaust. The flex discs both look good.

3. I found more rust......

4. I also found the modulator. It is in a tight spot but I will get it out. The question is do I have to adjust anything after I change it, or can I leave everything the way it is?

the ovp relay is a tall item with one or two fuses on top, the old version is 1 fuse and its quite common for this relay to go flaky and bad. If you still have no tach output then you would also be lacking A/C function as the klima relay also takes input from the tach sensor.

The sensor itself is located near the starter, its wiring plug is in the spot you found the OVP relay and all the modules, Its a simple two pin plug.

The modulator is ideally set by checking the transmission oil pressure from a port below the modulator but you can also set it by drive feel with fully warmed up transmission, there is a little T handle on the modulator that is used to tune the modulator and hence shift shock intensity - once done pop the cover on and you are done.

You can also adjust your old one like that.

__________________
2012 BMW X5 (Beef + Granite suspension model)

1995 E300D - The original humming machine (consumed by Flood 2017)
2000 E320 - The evolution (consumed by flood 2017)

A couple of more questions.

1. Does the modulator just pop off, or does it need to be be screwed out?
also when making the adjustment, what does it mean when i turn it clockwise versus counterclockwise. Does it get smoother or rougher when you turn to either side.

2. I found an OVP with 2 fuses from a gasoline wagon in a junk yard. I will put it in and see if it works. Does anyone know if they are the same relay? I would think that they are.

I drained the Trans fluid and removed the oil pan. I do not see a screw to drain the torque converter through the window. Do I have to try and turn it until I see it?

Yes. 27mm for crank or have someone bump starter

__________________
82 300 TD, 215K, 06 Dmax LBZ 245K,
2015 VW TDI Golf Wagon 70K

Be careful substituting an OVP relay from a different car unless the part numbers are identical. You might be OK or the smoke might come out. Note zulfigar's comment that the Klima relay won't work without the OVP relay so your climate control system won't cool. If you can get the a/c compressor to engage then the OVP relay is OK. Given the wiring problems of this model (mine had them too), the tach problem could be a wiring problem.

Jeremy

__________________

"Buster" in the '95

Our all-Diesel family
1996 E300D (W210) . .338,000 miles Wife's car
2005 E320 CDI . . 113,000 miles My car
Santa Rosa population 176,762 (2022)
Total. . . . . . . . . . . . 627,762
"Oh lord won't you buy me a Mercedes Benz."
-- Janis Joplin, October 1, 1970

Thanks for the advice -- didn't know about the fuse upgrade recommendation.

Jeremy

__________________

"Buster" in the '95

Our all-Diesel family
1996 E300D (W210) . .338,000 miles Wife's car
2005 E320 CDI . . 113,000 miles My car
Santa Rosa population 176,762 (2022)
Total. . . . . . . . . . . . 627,762
"Oh lord won't you buy me a Mercedes Benz."
-- Janis Joplin, October 1, 1970

you are most welcome

__________________
2012 BMW X5 (Beef + Granite suspension model)

1995 E300D - The original humming machine (consumed by Flood 2017)
2000 E320 - The evolution (consumed by flood 2017)

So I drained the torque converter as well. I did not have a 27mm turned the engine by hand pulling on the acc belt.

I still have a lot of body work to complete and once that is complete I will put everything back together and see what other issues are still present.

Has anyone ever removed the steering wheel on these cars. I am asking because of the airbag. My steering wheel is all cracked and I would like to replace it.

Not a problem.
1. Disconnect battery
2. Loosen 2 captive Torx screws in back of steering wheel holding airbag
3. Lift airbag off of steering wheel carefully, noting red 2-wire plug connecting airbag to steering column
4. Disconnect red plug, set airbag aside in safe place
5. Use steering wheel lock to hold steering wheel from turning. Note exact position of steering wheel before removing so replacement wheel can go on in same orientation. Loosen center screw holding steering wheel with 10mm Allen socket and long breaker bar. Remove steering wheel.

Reassemble in opposite order. When replacing the red plug in the airbag, the plug must make a significant that you will hear.

If replacement steering wheel is leather, treat occasionally with Lexol or something similar.

Jeremy

__________________

"Buster" in the '95

Our all-Diesel family
1996 E300D (W210) . .338,000 miles Wife's car
2005 E320 CDI . . 113,000 miles My car
Santa Rosa population 176,762 (2022)
Total. . . . . . . . . . . . 627,762
"Oh lord won't you buy me a Mercedes Benz."
-- Janis Joplin, October 1, 1970

To clarify, 1992-96 engine harness rot (depending on which engine), unfortunately

Aux fan low speed controlled by pressure switch, not temperature.