'80 300D / Changed Glow Plugs now it can't shift into 3rd gear

Hi all, I have a 1980 Mercedes 300D Diesel Automatic. I'm also a newbie at repairing it myself and decided to make it my project car. I recently had problems with it starting up on cold mornings. I did the
standard replacement of the glow plugs and it has been starting up fine. NOW what's happened is that when i get on the road, it will start off fine, kicks into 2nd gear fine, then stays in 2nd gear. The RPMs go really high and seems like it's stuck there. Did i do something when i installed the glow plugs? Also it was sitting for about a week before i installed them. Any help or direction would be great. Also is there a specific service manual anyone recommends over another (haynes, chilton, etc...) ?
Thanks, Mikey P
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Mickey, common sense is a good guide. It's difficult to imagine that a glowp plug could affect the transmission. Transmission shifts are actuated by vacuum ... you are going to have to replace some hoses probably.
I'm suprised at all those 123's out there, what the he..! Loved mine '81 but it's floor completely rusted out by '95 or thereabouts.... lucky people!
cheers, guenter
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I hope common sense is an actual service manual and you're not being a jerk. I'm a newbie and really didn't feel like being slammed for asking a question. Thanks for the hose advice regardless.
Guenter Scholz wrote:

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snipped-for-privacy@gmail.com wrote:

Relax, that was a perfectly friendly reply IMHO.
Ximinez
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and an almost fanatical devotion to the Pope....
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.... I have no idea what you are blathering on about. Why call me a jerk? jeeesh. So, someone who tells you to use your common sense is a jerk - OK I guess. You've never been 'slammed' have you.... hmmm.... ahh forget it.
cheers, guenter

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When you worked on the GPs did you remove any of the throttle linkage to gain access to the GPs? Especially the pressure rod (see next paragraph).
There's a "pressure rod" that runs from the top rear of the motor down to the passenger side of the transmission. The rod's position "tells" the transmission the throttle's power demand so the box will shift appropriately (at high rpm or low rpm). If the rod is disconnected the box will upshift quickly at low rpms (it "believes" the driver is applying almost no throttle).
Tell us a bit about the car, its mileage and when the transmission fluid was last changed, if known.
In the interest of information your car's transmission is a 4 speed automatic whose default is to start off in 2nd gear. 1st gear is achieved by shifting into L at a dead stop. 1st isn't the default because there would be too much creep while waiting at stops. The turbos idle in 2nd (to avoid creep) and downshift to 1st when the accelerator is pressed and the brake is released; this 2 to 1 to 2 is done for improved acceleration.
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T.G.-
I didn't remove anything when replaced the GPs. My hands were small enough and my wrenches long enough to work around everything. Which is why i'm wondering if i disconnected anything or knocked something out of place.
Some history... Well the milage stopped recording about 10 years ago and was at 80k and has been driven locally since then so maybe a 1000 miles per year if that. It's just our weekend car. Which is why i've decided (i'm not sure if it was the smart decision) to make it a hobby car to learn on and fix up. The transmission fluid was changed probably about 5 months ago by my regular merc. mechanic.
What was happening before i replaced the glow plugs is that it was having a hard time starting up in the cold weather. This lead me to replace them. Then it started up great in the cold, now it won't shift into a higher gear past the 2nd. Before that it was running great. Shifted fine into gear. So this again leads me to believe i did something to screw it up. Also this is not a turbo diesel.
T.G. Lambach wrote:

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phatnugs wrote:

Chilton's sucks. Bentley Publishers has the shop manuals on CD for $99, but it's unfortunately not actually available by following links on their site as far as I can tell.
Try this: http://www.bentleypublishers.com/product.htm?code=h763
It's ok. Unfortunately it's scans of the original manuals so it's not searchable, and the front end UI is in Flash so it's godawful in every sense of the term, but the information is there if you don't mind punching yourself in the face. Mine've guided me through a number of repairs so far.
-tom!
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I wouldn't go crazy trying to find a vacuum leak on it to remedy this problem. I know from experience that even though vacuum controls the shift algorythm, if there is not any vacuum at all the transmission will still shift through all gears. It may shift really hard, but it will still go through all gears. I know this because last week I lost the hose that goes from the vacuum pump to the brake booster, which also has all other vacuum lines feeding off of it. I realized it when I went to stop and felt like I was stepping on a brick. Then the car wouldn't shut off. but the tranny still shifted.
In addition to the linkages all over the top back of the engine, there is also a box that sits on top of the engine that has vacuum lines, cables and a wire going to it. it is about the size of a deck of cards. That controls the shfting, and if you disconnected anything from it, it may be causing the problem.
Hope this helps.
Good luck, Bill
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Thanks, i'll check out everything this weekend and post any success or failure. Again thanks for all the kind responses.
Mikey P snipped-for-privacy@gmail.com wrote:

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The car has done about 100K miles so the transmission should be OK.
Your work on the engine's glow plugs is independent of the transmission so why is the box not reaching 4th gear?
When you move the shift lever between P - R - N - D - S - L do you have the impression that the correct gear is being engaged?
My thought is that the shift linkage bushings may be worn and the box is actually in S when the shift gate shows D. But if it's really in N when N is shown on the shift gate then you can discount this idea. If the starter cranks the motor when the shift gate is in N then the neutral safety switch confirms that the transmission has the same gear as the shift gate and that's the second confirmation that the linkage bushings are OK and are thus excluded from further suspicion.
So it's back to the pressure rod - is it connected (at the top of the motor) to the throttle linkage?
Hope this helps you, if only to eliminate some possibilities.
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Perhaps a vacuum line has been pulled out of a joint. I've done the same changing filters.
Chris

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High all, Well i think i figured out the problem. Well actually you guys did. I took a longer look and noticed (please insert newbie speak), one of the cables/linkage that helps in acceleration was basically out of it's hook/holder. It looks like there were 2 links/cables that help accelerate and it was the closest one to you when you are facing the front of the car. This wire looks like it runs through a bolt then goes to a black box on the right side of the car (drivers side). Now the part that snaps into the accelerator is still a bit loose, at least it looks like it would snap in like the other cable but the part that snaps looks broken and the bolt that the wire runs through is broken at the top (the top part of the bolt is broken). I took it out on the road, and it still ran the rpms high but it finally switched into the next gear. After that it was good to go. I was going 40-50 mph with no problem after that. My next question is, that it looks like i need 3 parts. the part that snaps into the accelerator (or whatever it is), the part that clamps the end of the cable, and that broken bolt. Where can i get these parts? Should i go to my local merc mechanic and see if he can get them? And what are these parts called? Please feel free to correct any newbies speak. I'd like to know the correct terminology for all this stuff. Also i can post some pictures if i'm not expressing this clear enough.
Thanks again!
Mike
chrismhaney wrote:

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Is this a right hand drive (steering wheel on the right) car?
Best to post a url to a picture site (can't post pictures here).
As usual, it's the simple stuff that needs fixing.
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... define simple :-)
cheers, guenter
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Where can i get these parts? Should i go to my local merc

Evidently my car is significantly different from yours. I have an 84 turbo. But even though that means that I dont' know the name of the parts, I can tell you taht the dealer probably will. the really cool thing about the dealers nowadays is that they have pictures of everything on the car. You can go in just knowing what the part looks like and where it is on the car and with that they will be able to figure out what part it is, what it is called, how much it costs(the worst part) and if they have it or not in a matter of seconds. I've had to do this with vacuum lines."You know, they vacuum line that goes from here to there and it has that funny kink that goes like this..." Try the dealer. I think you'll be impressed with how friendly their database of parts is.
Sometimes not all parts have special names. The company will assign names, but something generic like cable retaining clip or something like that. so I wouldn't sweat it that you don't know the name of this little part.
Good luck, Bill
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