i'm attaching a photo of several devices that are attached to my 91 350sdl on the right side of the engine compartment over the drivers side wheel. dont know if you can tell but on the one on the left there is a nipple coming out of the bottom that has a plug that is leaking oil (slow). can you tell me what it is and what blue thing is next to it?

my 350 has no pickup and i think ive been told that one of these devices may be part of the problem.

thanks

Attached Thumbnails

 

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84 300 D Turbo, 222,000 and rolling, veggie most of the time.
91 350 SDL veggie wannabe

IIRC, that is the overboost valve....The intake manifold connection goes in one way and the line from the ALDA goes in the other way, and I think the switch is powered by a sensor on the intake manifold. If there's too much, it'll cut that switch off and the other "nipple" thing is actually a vent.


The thing that really helped me is to trace back both of the lines connected to that valve (the brass/silver box) and clean both of those lines really good. On my 300, the vent is up, yours appears to be upside down but i cant tell which way is up.

There's a banjo bolt (a hollow bolt with holes that makes air go from the ALDA and the intake to the tubing, and those get clogged up. Clean that out, it helped my acceleration

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Java Developer/Linux SysAdmin

Current:
*1984 300D ~200K,1989 MR2 250K, 2012 Ford Fusion 4.5K (fiance's car to replace the uber-unsafe cavalier)
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Past: 1998 Chevy Cavalier ,2005 Saab 9-3 2.0T, 1996 Mazda Protege, 1974 Porsche 914 2.0, 1997 Land Rover Discovery 4.0L/5Speed, 1995 Jeep Wrangler

The blue thing is a vacuum amplifier... it modulates the vacuum going to the transmission based on boost pressure. If it's broken (like mine was) you can just remove it and connect the transmission right to the valve on the injector pump.

The other device is the overboost protection valve. They like to plug full of soot and then you won't get fuel enrichment when the turbo spools up. It should normally connect the two lines running to it. On my SDL the plastic line running from the intake to that valve was plugged too. I had to replace it.

Note that in discussions of the overboost protection valve you'll usually see people with 3l engines posting, and in those cars that valve is mounted to the false firewall.

-Jason

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1991 350SDL. 230,000 miles (new motor @ 150,000). Blown head gasket

Tesla Model 3. 205,000 miles. Been to 48 states!
Past: A fleet of VW TDIs.... including a V10,a Dieselgate Passat, and 2 ECOdiesels.
2014 Cadillac ELR
2013 Fiat 500E.

I've heard a lot about eliminating the vacuum amplifier but I could not find the detail, step by step, or diagram on how to simplify the system. Could someone please post the instructions so we all can benefit from not having the complicated vacuum system.
thanks in advance MB lovers.

The "Blue Flying Saucer" (As 'Tis Known) [Mercedes Speak= Vacuum Amplifier] when CLEAN (Along with ALL it's ancillary parts) works VERY well.

'Have you stumbled upon the "Advanced", "Search" option YET?

I'm unaware of a DIY for it's "Improvement" (Removal),BUT then I'm not
looking.

You'll WANT to keep the Overboost Protection system working!

Your Journey will begin here:
Wastegate actuator swap for OM602.962?

OM603 specific:
OM603 Performance

Light reading for the Holiday:
Have theory: 603 #14 head fractures. part 1.

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'84 300SD sold
124.128

I've never heard it suggested that removing the vacuum amplifier is a good idea. It helps smooth out the shifts.

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1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13

I deleted mine (it wasn't working properly). You end up removing the vacuum feed to it, the associated lines, and hook the transmission line right up to the valve on the injection pump.

I may try to clean it and see if it works properly again, but my trans shifts great without it.

-J

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1991 350SDL. 230,000 miles (new motor @ 150,000). Blown head gasket

Tesla Model 3. 205,000 miles. Been to 48 states!
Past: A fleet of VW TDIs.... including a V10,a Dieselgate Passat, and 2 ECOdiesels.
2014 Cadillac ELR
2013 Fiat 500E.