No kick down on 240d auto trany - PeachParts Mercedes-Benz Forum

NC240D76 · #1 01-08-2003, 06:02 PM

I am trying to restore a 1976 240D that has been mistreated for years. I have it up and running well (with a little more smoking than I like) but I am not sure how to adjust the kick down on the automatic transmission. It is very sluggish from a dead start and shifts through the gears and into third before reaching 30 mph. It also doesn't down shift when trying to speed up or pass at any speed. I am unsure whether the linkage needs adjusting or if the little switch under the pedal is supposed to pull the trany down a gear.

NC240D76 · #2 01-10-2003, 08:09 AM

I had not received a reply to my first post so I thought I would try again. The car is a 1976 240d with automatic transmission.
Restore is the wrong word, I am just trying to get this car to run and operate as designed.
I bought it from the North Carolina DWI auction sight unseen for almost nothing thinking that this would be a good motor for a small workboat. After getting it running (ATF down the cylinders, new fuel and a good battery) I liked driving it so much that I started fixing things and bought a parts car.
The cars starts quickly until it gets below freezing then it likes the block heater first thing in the morning or it is hard to keep running, the rest of the day it starts great no matter what the temp is. It makes a good puff of smoke when first started and slightly noticable smoke after that.
It is very slow off the line and has shifted into third before thirty mph but will run 75-80 and keep on accelarating although it is loud at cruising speed (mostly wind and diesel noise).
I have checked the linkage for wot as suggested in another thread and the transmission does shift through all three gears but I have yet to figure out what if anything the kickdown switch under the accelarater pedal does. As far as I can tell depressing it does not make a differance at any speed or in any gear.
I also have a speedometer that registers 70 mph when running aprox. 62mph, is this adjustable? Thanks in advance for any help.

Work done on the car so far;
changed all fluids and filters and belts, rebuilt starter and all four calipers and replaced pads, new tie rod end, new tires, packed or replaced the wheel bearings, repaired the windshield washer footpump system and replaced the ignition switch and crossover lock. I also converted the ac to r134 and it will freeze you even at idle. (it did take me a while to figure the climate control system out)
Stole from the parts car;
Front seats, door and trunk locks, interior lights, switches and knobs and a side parking light.
Any advice on the kickdown switch, how to stop the smoking and how to repair or replace dry rotted vacuum lines to the locks would be appreciated.

ctaylor738 · #3 01-10-2003, 09:47 AM

Is it shifting twice through three gears, or shifting three times through four gears?

You should be getting three shifts through four gears, with first gear being quite low and short. If not, you are probably starting in second gear, which is probably a transmission modulator problem.

Your kickdown problem could be the linkage, the switch, the wire to the tranmission, or the solenoid in the transmission.

- when you put the pedal to the metal, is the switch engaging?
- if so, is it functioning (continuity check)?
- if so, is the solenoid engaging?

NC240D76 · #4 01-10-2003, 10:50 AM

I was not sure so I just drove the car to make sure of my answer.
It shifts twice, once at 20 mph and once at 30 mph and since the gear indicator only said l, s, and D I just assumed it only had three gears. I did get a downshift when I turned in the end of the road but it still shifted at 20 and 30 mph.
I checked the vacuum line where it branches off from the brake vacuum line and it seems to have good pull, can you tell me how or direct me to instructions to check/fix the modulator.
My meter is dead but I may be able to check the kickdown switch with a test light until I get another meter.
I have a cd on the 114/115 but it seems to be hard to use and books on the pre 77 240d seem to be much more scarce than the 123 model. Any preference between Chilton, haynes or whoever?

I checked your pictures, very nice! It seems you prefer the gas engines, are they as bullet proof as the diesels? I have a cousin that inherited a 1972-73 450 with low miles that has always been garaged but has not been driven in 10 years and not started in 4-5 years that she has no need for, as a quick guesstimate would this be worth playing with as a fun driver?
Thanks for all your help,
Brian

ctaylor738 · #5 01-10-2003, 11:30 AM

You are clearly not starting out in first gear.

If you start in L, you will force a first gear start. You should be quicker off the line and get a shift to second at 10-20 mph depending on throttle. L should hold the trans in second gear.
Shift to S, and you should go into third and hold there. Shift to D and you should go into fourth gear.

I have never tried to fix or adjust a modulator. The information is in the transmission manual, which is not on the CD and is hard to find. Mostly they are replaced because they are cheap compared to the labor to adjust or fix.

The 450 would be a challenge, but you seem to have a talent for this stuff. I would worry most about the gas turning to peanut butter in the tank and injection system, and the seals in the fuel system drying out. The climate control servo is probably frozen. If you do a search on Wayward Woman you can witness my trials in bringing a neglected 380SL back. They are fun cars to work on.

BobK · #6 01-10-2003, 12:49 PM

I am going to assume that your 115 is set up similar to my 123. The switch under the pedal operates a solenoid at the right rear of the transmission. On my 123 the wire had worn in half and then shorted out to the frame. I replaced about an 18 inch section of wire and put plastic loom around it to protect it in the future. Car will now downshift fine when you floor it. Still slow off the line, but that is the nature of the beast. BTY, the fuse for the downshift was one of two that ran the climate control. I ran the car with the switch under the pedal unplugged for awhile because every time I floored it, the car went into the failsafe defrost mode because the fuse blew.

NC240D76 · #7 01-10-2003, 01:05 PM

Thanks for the help.
I will trace the wiring with the test light and check the fuse(if so equipped). This car has manual climate control so only the fan should be fused( I assume).
I don't mind the slow take-off as long as the car is doing what it should and it will certainly be nice to have a kickdown when passing.
Looks like I will need a trip to Radio Shack for a meter before I do too much more.

Paul · #8 01-11-2003, 01:57 AM

you could be starting out in 1st but just shifting too quickly. the 240 automatics are slugs off the line. that year shouldn't have a vac mod. if it's shifting too fast try to go a little shorter on the kickdown linkage adjstment. don't go too short or it will stay in each gear too long until you let up on the accelerator or it will kick down every time you ever so slightly accelerate. make small adjustments at a time. you may have to go back and forth a few times before you get it where you want it. hope this helps.
paul

NC240D76 · #9 01-11-2003, 08:39 PM

Thanks for all the help.
What I found was a comedy of errors.
The carpet/floor mat was doubling over and possibly keeping the kickdown switch from being depressed, I checked switch and had power through the switch to the transmission when it was depressed so I fixed the carpet (after osphoing the base of the pedal).
While bouncing between the engine compartment and the transmission under the car trying to figure how to get to the linkage behind the exhaust manifold to adjust the kickdown I noticed the kickdown arm on the transmssion was very loose. I could move the throttle and linkage and everything looked great but the arm was rotating on the rod coming out of the transmission and not moving anything. I tightened the arm on the rod to give max kickdown and gave everything else the tug and wiggle test.
I took it for a test run and I am amazed by the differance, if you drive it easy(like my wife) it is still in third gear at aprox. 20 mph and fourth at 30mph but if you get on it the 2-3 shift is at 25-30 and the 3-4 shift is over 50 and if you kick it at 40-45 mph it will kickdown a gear and move!

I am wondering if I should back off the kickdown lever just slightly because you almost need to get out of the throttle to get it to shift into fourth when it is floored but it doesn't seem to downshift unneccesarily when accelarating between 30 and 50 mph and it seems to shift normally when driven easy or moderately

.
Any suggestions?

I also tested the transmission to see if it shifted as described above by c taylor. Mine is slightly different in that it will not shift out of first until I move the shift lever to S from L but it will shift to third without my moving the lever again and shifts to fourth when I move the lever to D. I am getting all four gears and your post helped me figure out what is going on. Thanks.+

It will out run my 6.2 diesel suburban now! (makes me wonder if I need to work on the suburban some)

ctaylor738 · #10 01-12-2003, 10:53 AM

u da man!

I personally like being able to hold the trans in 3 until you back off a bit on the throttle, but it's really your call.

NC240D76 · #11 01-12-2003, 07:02 PM

It also seems to shift harder but I think I will try it like this for a while. Do I need to worry about using different ATF? This car sat for several years before I got it but it seems to shift fine.
The speedometer is off and I need to find a way to adjust that and I had questions about the driveshaft bearing and shocks and body to suspension bushings.
Is it better to start a new thread or ask in an old one that did not start with these topics and hope someone picks up?
I have not been on here long enough to know proper etiquette.
Thanks for the help.

Ronkat81 · #12 10-03-2011, 09:40 AM

hey guys I'm having a similar situation but with a few more issues. . . please read and add any info that you see fit.

High Idle, White Smoke, shifting funny, HELP!! 75 240D

kerry · #13 10-03-2011, 09:47 AM

Quote:

Originally Posted by Ronkat81

hey guys I'm having a similar situation but with a few more issues. . . please read and add any info that you see fit.

High Idle, White Smoke, shifting funny, HELP!! 75 240D

Have you looked at the rod which the OP describes tightening? If you have the same model, it has a rod also instead of the bowden cable on later models. Adjustments in that rod should solve your quick shifting problem.

supercub · #14 10-03-2011, 10:59 AM

The transmission, if like my 1978, is supposed to start out in 2nd gear because the car is geared so low. If you floor it upon takeoff and hit the switch, it downshifts to 1st and will run through all 4 speeds (3 shifts). The rod on the left side of the engine controls the shifting. Pull the swivel joint off of the pin, behind the exhaust manifold, and screw it deeper onto the rod. That will make it shift later, at higher rpm's. If you unscrew it and it will shift sooner. Try one turn at a time and tighten the locknut against the swivel joint. The Benz service dept. will give you the correct shift speeds, or you can dig up that information.

Stretch · #15 10-03-2011, 02:45 PM

There's quite a bit of information posted on Benz World for the shift points and vacuum lines etc

DIY W123 Transmission Diagnose and Adjustment 722.xx OM 616-7 - Benzworld.org - Mercedes-Benz Discussion Forum