OK... I found a source of vacuum leak on my 92 300D. The line that runs through a filter and then through the bulkhead near the battery will not hold vacuum. Does that run to the climate control system? I can't seem to make out much on the few vacuum diagrams I found via searches. They indicate that this is vent line to the passenger compartment, but don't say specifically what they do once they get TO the inside of the car. Hope it doesn't have TOO many ends for me to locate and check!

Thanks in advance...

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1992 300D 2.5T
1980 Euro 300D (sadly, sold)
1998 Jetta TDI, 132K "Rudy"
1974 Triumph TR6
1999 Saab 9-5 wagon (wife's)

I believe that the line goes through the firewall into the pass compartment and ends. It is only a vent.

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Gone to the dark side

- Jeff

Thanks, Jeff. So wouldn't this act as a vacuum leak? Should it have a restrictor or something of the sort at the terminal end? Maybe my vacuum pumo is just weak or I have leaks elsewhere that reduce the vacuum enough to cause problems when that line is hooked up. Puzzling!

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1992 300D 2.5T
1980 Euro 300D (sadly, sold)
1998 Jetta TDI, 132K "Rudy"
1974 Triumph TR6
1999 Saab 9-5 wagon (wife's)

I think, and hope that someone will correct me if I'm wrong here, that the vacuum system when operating properly will pull air through this vent to "vent" vacuum-system components to atmospheric pressure when they return to their resting state (if that makes sense). Best to search for a vacuum diagram, but it might be that a vacuum valve is ruptured or stuck and allowing a constant flow. If I am correct (big if), then the vent line should NOT be Teed into any vacuum source, but coming from a vacuum component (which should then be checked).

__________________

Gone to the dark side

- Jeff

that sounds about right.

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92 300D 2.5L OM602 OBK #59

Thanks, all. I intend to take vacuum readings with and without that line in the system and see how much loss I am actually suffering with it in the system. Maybe it hits something in the CC system before venting (???). That would explain the odd behavior of the CC with the line removed and plugged. The temperature wheel doesn't really alter the temperature much at all with that line disconnected. I need to re-connect and re-check the temp wheel to make sure it's not just coincidence. In short, I just need to work that whole vacuum system over well I think!

Thanks again. All the help is very much appreciated!

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1992 300D 2.5T
1980 Euro 300D (sadly, sold)
1998 Jetta TDI, 132K "Rudy"
1974 Triumph TR6
1999 Saab 9-5 wagon (wife's)

If you follow the diagram and check from pump to devices that use Vac. You have a VAC side and a ATM (atmosphere) side. The work gets done on the VAC side. You might have several issues going on. On the AUTO climate control If you adjust to full limits FULL HOT or COLD Does the system respond properly? I'm in the process of having a new A/C compressor installed.

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92 300D 2.5L OM602 OBK #59

I need to find a full size pdf of the vacuum diagram... the ones I can find posted here are lo-res and I can't read what's what on them. I have a Haynes manual on order, so hopefully there might be something in there that I can use.

As for the CC system, it does work well AT TIMES, but last night, with the "vent" line disconnected and plugged, it would only blow hot, even with the wheel in the cold position. With it in the full cold detent it would finally get a little cooler, but not as cold as it should be, I don't think. I'll dig into it further when this rainy cold weather clears up!

Again, I appreciate all the guidance.

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1992 300D 2.5T
1980 Euro 300D (sadly, sold)
1998 Jetta TDI, 132K "Rudy"
1974 Triumph TR6
1999 Saab 9-5 wagon (wife's)

I think this post has the VAC Diagram you need. EGR -- when does it actuate? 92 300D

I'm referring to the above diagram below:
If I understand you plugged the line going to #26A on the left side.
The nice thing about VAC lines is that their is no magic to them. Just follow
I'd start at the pump. Carefully follow the lines. You'll follow to the 4 way Follow to the left and you run into all the EGR/Boost stuff. I had several issues I had to fix. Use a high lighter to keep track.

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92 300D 2.5L OM602 OBK #59

Thanks -- that diagram is exactly what I needed! High enough res to read the fine print!

Yes, I plugged 26a on the left. Looking at that diagram, I wonder if it wasn't plugged into the wrong line; I will check tomorrow, but it almost seems that it was on a vacuum supply line, not on a line coming from a vacuum component. More tomorrow; thanks!

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1992 300D 2.5T
1980 Euro 300D (sadly, sold)
1998 Jetta TDI, 132K "Rudy"
1974 Triumph TR6
1999 Saab 9-5 wagon (wife's)

That line might go to the vacuum reservoir under the passenger wheel well shroud.

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1987 300TD 309, xxx 2.8.2014 10,000 mile OCI


Be careful of the toes you step on today, as they may be connected to the ass you have to kiss tomorrow. anonymous

“Be who you are and say what you feel, because those who mind don’t matter, and those who matter won’t mind.” Dr. Seuss

Well, I have no idea what's going on, but now I have boost and that line is hooked back up. I just fiddled with a bunch of connections and temp-installed a boost gauge, and voila... 15psi (or so) peak boost (blowing off to 11 or so, I guess). I'm not complaining!

Seems something fixed itself; I won't ask questions!

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1992 300D 2.5T
1980 Euro 300D (sadly, sold)
1998 Jetta TDI, 132K "Rudy"
1974 Triumph TR6
1999 Saab 9-5 wagon (wife's)

I love it when a car heals itself. Long live Christine!

__________________

Gone to the dark side

- Jeff

AWSOME!! Next project???

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92 300D 2.5L OM602 OBK #59

Babymog, you have no idea how much you helped me out with this old thread! I pulled my dash and for the life of me couldn't figure out where that line went! It goes nowhere and is just a vent! Thank-you so so much!