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D_Ryan 02-14-2005 02:47 PM

Vacuum line routing pictures

I've looked throughout the Forum, and still can't quite find what I seek. I found the "logical" vacuum diagrams that "BoostnBenz" put up (and a huge debt of Thanks for that), but what I'd really like are some detailed pictures that show the actual routing paths/groupings.

The '85 300TD which I inherited is the recipient of a long-block replacement, and I don't believe everything is as it should be. The car runs fairly well, but there are some niggling performance problems that I think may be vacuum related. The car is a California model, but I don't know how much of the California configuration may still be there.

I'm of a mind to go through and start replacing all the vacuum "plumbing", and I'd like to do it right, not merely copy what is in there now.

On the same note, what is a good source to obtain the various hard and soft tubing (in bulk) used? The line feeding manifold pressure to the ALDA was hard and brittle at the manifold banjo fitting fit VERY loosly at the banjo fitting. There was enough slack that I cut it back and reattached the fitting.

Thanks all

dieseldiehard 02-14-2005 03:54 PM

D_Ryan said: "hard and soft tubing in bulk - used"
did you mean "new" ? New bulk tuning is not too expensive, I'd not use any used lines.
Old vac lines that get brittle should be replaced to prevent leaks. Usually you can replace the section of line nearest the engine in the engine compartment and splice it where it nears the firewall if it is still pliable there (the heat near the engine seems to make that portion more brittle). I use a short piece of silicone rubber hose as a splice, I find it holds up longer than rubber tubing.

See this thread for part numbers (thanks to gsxr for that info):
vac tubing is color coded for the application, but replacement can be neutral (no color) or any color as long as the diameter is close to that of the original. MB uses different diameters to prevent the vac system from loading down or losing vacuum too quickly, as in the different sizes of pipes used to supply a home or building, larger close to the source, smaller as you branch out. They also may have wanted to induce a delay in the vacuum action by using a small diameter.
I have some excess small vac tubings, neutral and black mostly, if anyone wants to buy at my cost send me a PM and I'll check it out.
The line to the ALDA however is not something I have though. When I need it I buy OE (factory) boost/ALDA lines with the banjo fittings already installed, that BTW is LARGE diameter tubing for a good reason - they want the boost to get to the ALDA post haste, unfortunately the banjo bolt that goes thru the fitting at the manifold gets plugged easily.

dieseldiehard 02-14-2005 04:01 PM

vac diagram info here:

D_Ryan 02-14-2005 04:45 PM


Poor phrasing on my part; "used" referred to 'what the factory used', not new vs. used. I am looking for a source to obtain new lengths of the tubing used throughout the vacuum system.

Again, I've been to the logical diagrams showing what connects where; I'm looking for actual pictures or drawings of the layout on the engine/in the engine compartment, especially for an '85 California model. As an example, the engine in the car has no "black box" control module atop the valve cover, should it?


dieseldiehard 02-14-2005 08:55 PM

no, the '85 uses a electrical switch inside a small black box atop the valve cover, instead of the vacuum valves used with other 123 diesels, this switches the EGR, which should be disabled in you car (for test purposes ;) )

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