Can Someone Tell Me About This 300SD Vacuum Line??
 

Guys...While tinkering around with my 85 300SD this afternoon, I found this vacuum (?) line unattached. Please see photo and let me know if you can tell me where to relocate.

You guys are great!

1985 300SD (A Beauty) Astral Silver
225K

I am fairly sure that that is the *PRESSURE* line that goes from the banjo bolt on the intake manifold to that black plastic switchover valve on the fake firewall. This line supplies pressure to the alda, telling it how much fuel to supply.

Yes that line looks to go to the switch over valve.

It's called the "overboost protection valve" and the line goes to the open nipple on the bottom of the valve. While you have the line off, you should blow some compressed air through it and make sure it is clear. At the other end of that line is the "banjo bolt". There is a hole through the center of the bolt. Take the bolt out of the manifold and make sure that the hole is clear. Use brake cleaner and compressed air, if necessary.

It may be that the reason it is disconnected is because the rubber hose that attaches it to the overboost valve has perished and broken. You'll find it much easier to deal with if you remove the two phillips screws that hold the valve to the firewall, you can then see the underside of the valve where this line should attach.

With this line disconnected your fuel mixture is not being enriched when you develop boost from the turbo, so performance will likely improve with it reconnected.

Kevin

I agree with Brian Carlton. I would also clean all that out (banjo bolt, manifild, line and overboost senor) with brake cleaner and blow compressed air through the line and sensor. Lots of Soot in those areas!!! I had the very same issues. If that Line was off that means that your car was/is a cow! You are probably not getting a boost signal to the ALDA, therefore, when your turbo kicks in zzzzzzzzzz Nothing happens. Check here...many people helped me when I had a problem with mine. Hope this helps!!!

http://www.peachparts.com/shopforum/showthread.php?t=102183&page=1&pp=15

You Guys Are Great!!!
 

Thanks for the wonderful help...I feel like a member of a special fraternity on this board and I've only been on since I got "Klaus" in late September. Thanks again everybody...

Anytime.

Help is what we do here.

Even when it appears we're out to scare the wits out of anyone considering a 3.5 we do it out of a sense of caring :D

Sixto
95 S420
87 300SDL