617 Vacuum layout

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skullion
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Hope someone can help! I need to track down a correct Vacuum layout/schematic for my 1980 300GD engine. I have looked at many different schematics/websites/forums and none seem to match what is in the engine bay! The auto box is mucking about and I need to eliminate the vacuum side of things. Thanks very much for taking a look.  Marcus.

 

cox.adrian
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Re: 617 Vacuum layout

  marcus

​            you say the  auto box is mucking about  !!!!

            whats it doing  ??

                no kick down /  wont change up / down  stuck in gear ect

Arnie
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Re: 617 Vacuum layout

There's a vacuum switch/valve [64] on top of the cam-cover where the throttle linkages are mounted. Check this and its vacuum line connections. Replace if it looks worn.

The basic vacuum circuit is given below:

Some typical problems and causes listed here:

https://mercedessource.com/problems/transmission/does-your-automatic-transmission-really-need-replacing

 

 

 

The picture below is for US turbo 617 with emissions control (not applicable).

skullion
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Re: 617 Vacuum layout

  marcus

​            you say the  auto box is mucking about  !!!!

            whats it doing  ??

                no kick down /  wont change up / down  stuck in gear ect

Thanks very much for the reply...

so, Its reluctant to change up unless the revs get right up, it stays in gear going up hill/under load but going down hill will tend to coast then when applying throttle will engage 1st... which can be a little alarming. (lucky I live in the Devon lanes where 30mph can be scary).  Have replaced all gearbox fluids (bled right through properly) put a new filter with gasket set in. Kick down is disabled by hose removal and the little plastic vacuum diverter also replaced.

 

Ideas?

skullion
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Re: 617 Vacuum layout

Thanks Arnie... will ask round for a vacuum tester! though when my friend tested it all seemed ok apart from the little plastic vacuum diverter... which I replaced, and it's still not right. Will digest.

Arnie
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Re: 617 Vacuum layout
skullion
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Re: 617 Vacuum layout

 

 

 

Thanks again... the weekend beckons!

cox.adrian
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Re: 617 Vacuum layout

   Marcus

​                      this is only a guess 

                       you must have vacuum as if not your engine would not stop

                      if you have no leaks in the rubber connectors cracks in the pipe work

                         i would be looking at the valve in the side of gear box 

                       # 100   on arnies  pic

                       

Arnie
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Re: 617 Vacuum layout

This is the basic layout, which, for some reason is not showing above:

The valve on the throttle linkage (64)  is also very important.

 

 

 

 

 

skullion
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Re: 617 Vacuum layout

 Thanks all for your help. Should be able to work things out now with all the helpful info. Vacuum tester on its way. Valve 64 replaced with a new one, got a spare gearbox valve somewhere... surely nothing can go wrong...