Vacuum diagram for 79 non EGR W116 300SD

[DieselW108]

Hi,
Does anyone have a vacuum diagram for a 79 non EGR W116 300SD with the sizes of the orifices too?
Many thanks!

[charmalu]

Welcome to the forum.

Hope this helps, click on the Tech Info and the MB link, there are vac diagrams for quite a few yrs and models. hope this helps.

MZF-Bayer Transmissions

Also in the Condensed Sticky thread at the top of the page is this.

Vacuum Diagrams

Charlie

[kerry]

What kind of problems do you have? You have the evil servo with a zillion vacuum lines.

[DieselW108]

Thanks for the replies.

I've visited most of the links previously and none of those have the info that I'm after. I have a 1969 W108 280SEL fitted with a 78/79 W116 (300SD) 617.950 turbo diesel WITHOUT an EGR. I understand that the EGR was not fitted to the 617 at this time. There's certainly nowhere been blanked off for it and there's never been a switch over unit on top of the valve cover.

Problem is that ALL the vacuum lines are missing except a small feed from the vacuum pump to an engine stop switch and then back into the injector pump engine stop. Everything else is missing. I understand that there should be a link to the transmission modulator and a vent into the interior plus a series of orifices but can't find any diagram without the EGR shown. Do I just need to interpolate from an EGR diagram?

If anyone has a non EGR 78/79 W116 300SD (with a standard set up) and wouldn't mind taking a picture of the back end of the injector pump, that would be fantastic. Be great to know the colour of the orifice connectors too so I can order some new ones.

Thanks again.

[kerry]

What symptoms do you have that you are trying to resolve? I disconnected the vacuum line from the transmission on the 79 SD I used to own because the transmission shifted much more crisply without it. If you are getting really hard shifts, then the vacuum line to the transmission would smooth them out. If it's shifting fine, I wouldn't worry about it. Do you have the Vacuum Control Valve on top of the back of the IP. Without that valve the system won't work because it varies the vacuum to the transmission on the basis of the position of the rack.

[DieselW108]

The vacuum control valve is all there. I have really hard shifts because all the vacuum lines are missing.
What I really want is a vacuum diagram (with all the orifice sizes) for a non EGR W116 300SD. I'd like to set it up as stock and start from there.
Many thanks

[kerry]

There is a complete W116 shop manual online somewhere. Don't know if it has the vacuum diagram. It's a site devoted to the W116.

I think you just need a line coming off the main brake vacuum line with a T feeding into the top of the VCV and the line continuing down to the transmission modulator as I understand it. Put some kind of orfice in that line and monitor the levels of vacuum going to the modulator as you drive.

[sleepstar]

i believe i have this somewhere. i have an 81 w123 but it has the trans from a 79 SD in it, so the vaccum lines are all configured as if it was a w116. mine had an egr but i removed it (for testing purposes) and routed everything like it was a w116. i dont have orifice sizes though, sorry. i can try to find the one i used or i can take a picture of my engine??

oh also, mine does have the switches on the valve cover because in this instance, they are used to control the transmission (i know on MOST they control the egr, but in fact they do control the transmission on the 722.120 series trans)

[sleepstar]

actually it comes to mind to ask if the tranmission in your car is the 722.120, which was on 78-80 300SD? i dont think a w108 would have a transmission controlled by vacuum from the engine, it might just have an independent modulator on the trans?

[Ether]

Look here

Mercedes-Benz Model 116