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Discussion Starter #1
Hello,
I have 1991 300D 2.5TD automatic. It has almost 217k miles. The car has been running great. The previous owner was German, so she did everything on this car in terms of maintenance. Almost 10k miles after I bought it, the car is acting weird. It all started on the freeway. I was doing 75mi/hr on cruise control, when the RPM would increase but there would be no power to the car, so there was no 4'th gear:rolleyes:. I assumed it was my transmission that was slipping. Now the car would change gears up to 3rd but would never engage 4th gear. After few days now the car doesn't have any power on D or shifting. The way I concluded that the transmission is okay because I can drive by selecting 3rd gear, and it shift smoothly between 1-3 gear. Today in the morning I noticed that the car has no brakes as soon as I start the car from my drive way, but the brakes come back.
I also have a whisy noise coming after braking for a stop sign:confused:.

Guys, please share the solution, if you had a similar problem with your car.
I would greatly appreciate your response.
Thanks.
 

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Discussion Starter #3
Hi Akharmon,

Thank you for the reply. I was thinking in the same line, like the vacuum pump, modules or the VCV.I'm not sure what it is. I'm planing on troubleshooting in three weeks. I just wanted to see of anyone out there has had the same problem and was able to solve it. I would appreciate it.
 

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money pits of various forms
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Vacuum all around it sounds like to me. Get out the mightvac! Also check to see that your kick down switch is working properly.
 

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Discussion Starter #5
Hi Winmutt,
I will be doing vacuum check pretty soon. I would like to ask you where is the kick down switch located it?

Thanks.
-D
 

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money pits of various forms
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Under the go pedal. Sometime carpet gets stuck up under there and prevents the car shifting to 4th. Your problems, however, sound entirely vacuum related. No vacuum on the trans is hard shifting so yours must be getting too much. The VCV can be adjusted by rotating it as listed in the manual.
 

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Discussion Starter #7
Hi,
I have encountered that issue before. But I believe this is strictly vacuum related problem. The car won't even shift on any other gears when "D" is selected. I've been driving on 3rd gear for the past two weeks, and it has no problems shifting.

Thanks,
_D
 

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Discussion Starter #8
Hello everyone,
I'm out of school and I would like to start troubleshooting my car. The current status as of 12/22/10:
The car shifts fine on all first three gears but never makes it to the fourth gear.
The shift works if D is selected or just left on 3rd gear.
The other problem I have noticed is that when I first start my car in the morning, I lose my brakes for a second and they work after.

I'm thinking more towards a slipping 4th gear, but I'm sure.
I'm sure this forum has someone that has superior Mercedes knowledge and can provide some tips for me.
Do you think the 4th gear is gone because of vacuum problems related to the modulator or any other vacuum dampers in the systems.

Thank you again and in advance for your help.
 

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86 190E 2.3L 16V, 2 95 320TE's, 02 S500
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No brakes on start up = loss of vacuum. I suspect vacuum, or more accurately lack thereof, is the problem with 4th gear.

Jayare
 

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Discussion Starter #10
Jayare,
I was thinking on the same lines. I would like to know how are the breaks linked the the vacuum system. Do you think is the reservoir that is losing vacuum. If the reservoir system is bad, how is it related to the 4th gear.

The other thing is how is it possible for only the 4th gear to be gone, where every other gear and shift works fine.

Thank you,

_Danny
 

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1987 300TD
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SO was this a vacuum issue? I have tried everything to get the 4th gear back on my 93' 2.5 300d...replaced the k2, fluid flush and filter change..Is my transmission shot or is it simply a vacuum problem? It shifts fine 1, 2, 3...but 4th is revving, slipping just BARELY engaging, u wouldn't even know it is barely engaging without really paying attention...mostly just revving'/slipping...PLEASE HELP. THANK U.
 
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