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.