1986 Mercedes 300 SDL slow after having the transmission rebuilt. HELP
 

Good evening all

I have a 1986 Mercedes 300 SDL 280, 000 miles. I just had the transmission rebuilt and I have noticed two problems.

1. The car is slower than normal and takes some time to reach normal speeds. Once she gets going, it will reach normal speeds. When I think about it, the turbo may not be kicking in either. The guy that did the rebuild said that the transmission I gave him to rebuild was slightly different from the one in the car. He said the one in the car was electronic Nd the one used to rebuild was a mechanical setup. He said he made the adjustments to the rebuilt one to make it work.

When I got the car yesterday, he said to check out the throttle body. That is why I am coming to the forum for suggestions ?

2. The speedometer and odometer isn't working. Neither was working prior to the the rebuild and still not working. The mechanic suggested I replace the speed sensor on the side of the transmission. I went to ths Mercedes dealer and they said the wiring harness is over $300. One of the techs at the Mercedes dealer suggested it might not be the wiring harness for the speedometer, kickdown switch and etc.

Help me on where to start....

Thanks in advance

Ron

Wow, he suggested check the throttle body on a Diesel?



Have you checked the fuses? Have you swapped a known good cluster?



Check the linkage at the firewall, the 10mm nut can loosen and give you very little pedal travel... thus very little fuel.



Did you have your existing transmission rebuilt or what? I am not following what you have done

1. I purchased a donor transmission and had it rebuilt. Then he took my car and swapped out the old transmission for the newly rebuilt one.

2. I will check the fuses. Any particular ones I should focus on?

3. I have not swapped out a known good unit. Can I use a donor from a gas or diesel?

4. So which way should I turn the nut for the lingage?

Thanks

Ron

So was the donor transmission from a 300SDL?



You will have to check the fuse list to see what runs the gauges, I do not know off the top of my head. Also, if you have never cleaned the holding pins... go ahead and do them all while in there.



Cannot say with certainty, but I figure a gasser speedo head would work... it will not read accurately due to gear ratio differences.



Snap a photograph and post the linkage up. I can then compare it to mine, this happened to my SD and SDL... both were so slow, they could barely get out of their own way.

Of course you may have an issues with the ALDA or the over boost protection valve.

Tell us which transmission has been fitted. There are some numbers starting with 722... on the right hand side of the transmission casing just above the oil pan.

If I read the numbers correctly:

721-2712101

Understand that I had a whole lot of belly trying to wiggle under that car.... trust me, it wasn't very pretty.

The turbo is not kicking in and it did prior to the install.

Unfortunately those numbers mean nothing to me (oh Vienna).

You need to find a set of numbers on the transmission in this form 722.XXX (we need to know what the XXXes are)

Of course if you have no turbo boost...

I will snap a pic of the linkage of which I am speaking, if you turned that camera 90°... that is the area.

Do you have a boost gauge to verify no boost? Usually 603s have low fueling issues making them dogs. Bad ALDA, plugged overboost solenoid, and slipped linkage are the common causes. Even the plugged catalyst on the '87s and CA '86s too.

Finally found the correct numbers:

722.317 02891647

These number came off the transmission

Ron

1986/7 300SDL should have 722.321 tranny
1987 300D has 722.317.

They can both mate into the OM603 engine but I do not know the difference between the tranny.

Well it sounds to me like the speedometer drive was swapped over.

I don't think that there's any real panic to be had between the two transmissions - I don't know the exact differences between the two; if you have any trouble between the two it would probably be shift points.

What kind of deal was made with the person who did the work?

It sounds a bit strange to me that the turbo appears not to be working and the speedometer doesn't work and yet you're not taking it back.

What's the story?

the 317 has a mechanical speedometer gearing, the 321 has the electronic speedometer drive...

no turbo could mean the tech attached vacuum to the alda... or broke the alda hose, or any number of other problems keeping the alda from enriching the fuel...

yeah... the mechanic wants you to check out the throttle body? um... there's no throttle or throttle body on this diesel... perhaps he means the rack on the IP? or the ALDA ? maybe he meant the wastegate? oh... he might mean the arv... it's a throttle of sorts... and if it's disconnected, but still attached to the air plenum, you'd be running little air... do you have black smoke?

Thanks for all of the input. The speedo didn't work prior to the rebuild. I am willing to think there is something wrong with the speedo unit itself. The turbo issue, there isn't any black smoke. As mentioned, it is sluggish an eventually reach normal speeds.

I am trying to understand the issue for myself. I also wanted to understand that the transmission used was compatible.

Disconnect your alda completely. Drive. see if you have turbo. if you have turbo then there is a clog in your boostline. these things scunge up with carbon sometimes and just blocks. try swapping your cluster for a diff one, I had a space cluster but I sold it. they are pretty interchangeable but if you can find a diesel one.

Thanks, I will try that and report back.

Slow may be very early shifting up. If you have a tach and it works mention what it is shifting up at.

The points on the tach when the shifting is happening is 13-14 on the first shift into 3rd, and 17-18 when shifting into 4th gear. And disconnecting the adla did not make any difference or change in the shifting process.

Ron

Pedal position too
 

Shift points have no meaning without pedal position. Though they do seem a little on the low side, even for <1/4 throttle. Test at 1/4, 1/2 and WOT and post results.

MBZ123

I tried it with the pedal at the different points mentioned, and the results are the same. Lets me know what else I can provide or try.

Did you snap any other pictures of the linkage? Check the stuff right behind the oil filter canister.

Have someone depress the accelerator pedal fully and watch under hood to see if the fuel rack fully opens.

Checked the movement of the accelerator vs. Throttle linkage and it moves as expected. The engine revs high as expected. It seems that the problem is in the response during movement.

The pics are the best I can get around the oil filter housing. There is some play in the cable that connects to the linkage with the black krinkle cover.

Your lack of performance is because the system that regulates shifts is not working. As you apply more throttle the shift points get later.

This enables the engine to get into it's power band. The archives will have many articles. This is regulated usually by vacuum or mechanical linkage. Some method of telling the transmission what the engine wants.

Personally I would forget the engine currently until you have your shift issue solved. If the engine cannot get into it's power band during acceleration it will be slow.

Here is the angle I am asking you to show me:



http://img.photobucket.com/albums/v4...SDLlinkage.jpg

Thanks so much for helping me see what you had been referring to. I think the turbo isn't kicking in.

My SDL runs great, I have full opening of the fuel rack with my linkage.

Please have someone sit in the driver's seat and depress the throttle fully (keep it down, vehicle off)... while you are under hood, manually operate the linkage to verify you are having the fuel rack open fully. Your linkage is different than mine from the photographs. The turbocharger is going to have a hard time lighting off the EGTs are not high enough due to lack of fuel. Been there, done that.

My SDL could not get out of its own way when I bought it. I had the linkage issue, a bad overboost solenoid, and a plugged cat. Once the linkage was fixed, it moved decently despite lack of fuel enrichment from the ALDA due to the overboost solenoid. Once I fixed that, I was surprised how well the car ran.

The shift timing will be off if the linkage is not pulling that bowden cable properly to make the shifts at a 'normal' time. That is why I keep going back to the throttle linkage to suspect first.

I could not remember if the SDL had a Bowden cable or if only the SD had it.
When I bought the SDL, it had zero power too. In fact that was why it was for sale. I took the ALDA off, changed the fuel filters and fixed the linkages and it got a lot better. Once I got a boost control for the turbo and took the boost from 7psi to 13psi.

My suggestion is to look at the bowden cable, start turning it counter-clockwise ( if iI remember correctly) about 1/2 turn then drive the car. the shift points should start at higher RPMs. Keep doing that until you are seeing faster performance. Once you have the transmission shifting at the right RPM, remove the ALDA, don't just unplug it, take it out.

There are lots of posts on adjusting the Bowden cable, so do a search for that term. Do a search on removing the ALDA from the OM 603 in the SDL, the clearances are pretty tight but you can do it.

Good Luck!!

The turbo runs off the engine exhaust. Assuming it is turning only the waste gate being stuck open will result in no pressure. The waste gate is spring loaded and as the pressure increases on compressor side of the turbo it opens the gate to keep the boost pressure from getting to high. I adjusted my 90 350 SDL up to 15 psi to get more power. Yours is probably set to 8-10 psi. Get a boost gauge and connect it in the pressure line to see if your turbo is working and at what pressure the gate opens. The ADLA is a device that corrects for Atmospheric pressure changes and can be adjusted to push the fuel rail in further to effectively increase the mixture. There is an overpressure protection device which will back the rail off if the turbo overpressures but other than that the turbo and injection unit operate separately.

I took the car out and made several adjustments to the bowden cable and it made no difference in the car's performance. I will continue to try the other options mentioned.

If nothing is changing with the shift points after adjusting it. Providing your bowden cable is in the range of changing the shift points. You may have an internal transmission problem.

You have had a look to verify it is hooked up on the transmission? Another possibility is you changed transmission types and the length of you current cable may be wrong. It may take two people to have a look.

One watching the transmission end of the cable and the other manipulating the linkage up on the engine. Under fairly hard acceleration it probably should not shift up till around thirty miles per hour as a guess. Certainly not at 14 mph as under very light acceleration conditions.

Of course you are tending to fixate on the turbo etc. With an early shifting transmission the engine does not get up into the revs where the turbo boost comes on line so it is normal to have no apparent turbo involvement. Go with the obvious issue first . If others are there later fine but you cannot ignore the shift points remaining the same at various power demand levels.

Do not complicate this more than required.

Okay Barry I hear you. I am focusing on the turbo and I appreciate you candor. I will test the cable as you mentioned. I will update all once that step is complete. When I mentioned the the shift points were as stated, the numbers represent 1400 rpms and etc on the tachometer. When I check the movement of the bowden cable, do I need to have the rear wheels off of the ground?

Car does not have to be running. You may have to elevate it to see the transmission connection or not. I guess it depends. What you want to establish is that as the linkage to the injection pump is advanced. That there is a corresponding movement on the bowden cables transmission end and that it is moving the activation device on the transmission. My guess is that if there is good movement under there that the control the cable is changing is not working inside the transmission.

Even if this becomes the case it should not require removal of the transmission. That control rod probably controls something in the valve body. I am not a transmission type though remember.

The turbo has basically no effect unless the engine can rev up beyond 2000 rpms has to be kept in mind. Early shifts up do not allow this. On slow acceleration such a situation is okay. Still when you want power the engine revs before the shift points must be well over 2000. The bowden cable enables much later shifting up under demand from the linkage to the injection pump. For example if the accelerator pedal is 3/4 down the shifts may be delayed until 3500 rpm is reached by the engine.

If you have driven other cars with automatic transmissions you probably have noticed that the more fuel given the later the transmission shifts will be. This is by design even with non turbo cars but especially required on turbo engines to get the benifit of the turbo.

Thanks Barry for your advice. I will take heed and I will follow-up.

It is just where I would look for the problem first. The linkage at the transmission the bowden cable controls may be suspect. The control rod usually has to be hooked up to the valve body when the transmission is put back together. Maybe not on this brand.. Still this may just have been missed is still a possibility.

My own particular issue was when I purchased an old 114 gas mercedes for the transmission. It too held the shifting up too early points on accelleration.

Like yours they remained the same no matter how much or little I gave the pedal. One of the controlling rods ball joints had rusted apart. The rod served the same purpose as your bowden cable does.

It is all starting to come back to me... On the SDL there is an electronic kick down switch under the accelerator. Check to see if the carpet or floor mat is interfering with it. It runs off the same circuit as the mono valve for the heat, so if you have heat all the time, the fuse could be blown. I found this out after the insulation wore out on the kick down in my SDL and the cabin heated up!

If you are running and you floor it, does the transmission drop into a lower gear?

I think the Bowden cable was probably left disconnected by the transmission shop...

Did you check out the remainder of the linkage other than the bowden cable?

If the linkages that control the IP/etc are out of adjustment or something, they can easily cause problems.

Just for the record here in this thread. I had the transmission removed from my 87 SDL to replace seals, gaskets and pump. When I got it back the shift points were all at higher RPM and it was due to lack of power because the turbo was not working properly because the vacuum line to the ALDA was left un-connected. Once I discovered this it was like getting a new car back. Much more power and shift points were back to normal. It was a simple fix to clean out the vacuum line and hook it up where it belonged.

Great that it was fairly simple and did not involve The internal trasnsmission parts in the end.

Plus thanks for mentioning on site what you found.

A question on the 87 300sdl ,does it have the linkage joint at the firewall from the accelerator pedal like the 77-85 300d ? If it has anything similiar to this plastic ball assembly I would check this for failure .Lube up all your throttle links from the accelerator pedal to the throttle rack with lithium grease ,then I would find any possible points of failure for the throttle .This could easily be a bent linkage rod also for one important fact and that is to remove this transmission a gorilla wearing overalls with a pry bar in hand was inside that motor area freeing up the old trannie off the motor.

1987 mercedes-benz 300d transmission problem
 

Hi everyone, my 1987 300D doesn't shifts to 4th gear. Before didn't shift to 1st and I have replaced Brake Band B1 and got it to work. Now 4th gear is not working, could that be Brake Band B2? Checked all clutches they look fine, thank you for any help

The most common reason for this is that the kickdown switch is shorted. Unplug the kickdown solenoid and see if the problem goes away. If it does, replace the switch.