How do I test the overboost protection switch to make sure that it vents through the top of the switch in an overboost situation?

-Joe

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'81 MB 300SD, '82 MB 300D Turbo (sold/RIP), '04 Lincoln Town Car Ultimate

Sooner or later every car falls apart, ours does it later!
-German Narrator in a MB Promotion Film about the then brand new W123.

Hi Joe,

the switch in the manifold: I fixed a hose from the compressor to the thread of the switch and checked with gauche and voltmeter. 1.2 bar I think.

the valve on the firewall: blow in from the manifold side and check the way to the IP. Give 12 V to it and check whether the way to IP is shut and the valve is vented.
For a short test you can hear the click when giving 12 V.

Tom

I believe the switch on the manifold itself is fine. How do I give the switch on the firewall 12V?

__________________
'81 MB 300SD, '82 MB 300D Turbo (sold/RIP), '04 Lincoln Town Car Ultimate

Sooner or later every car falls apart, ours does it later!
-German Narrator in a MB Promotion Film about the then brand new W123.

the switch on the manifold brings ground to the valve.
Just disconnect the socket of the manifold switch and bridge to ground. Then you should hear the click of the firewall valve.
Or: disconnect the socket of the firewall valve and test the pins. The BL/YL/RD should give you +12V the BR/BK, leading to the manifold switch should give you nothing until the shut off pressure is reached.

To believe that the mainfold switch is o.k. is not enough in my opinion.
I feel better being sure it works.

Tom

Mine hasn't even been hooked up since I bought the car. I 'm doing fine without it.

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'85 300SD (formerly california emissions)
'08 Chevy Tahoe
'93 Ducati 900 SS
'79 Kawasaki KZ 650
'86 Kawasaki KX 250
'88 Kawasaki KDX200
'71 Hodaka Ace 100
'72 Triumph T100R

Until your engine blows up.

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1984 300SD Turbo Diesel 150,000 miles

OBK member #23

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you will continue to be fine too, until your wastegate hose breaks, developes a leak, or pops off. Then you have problems.


The overboost solenoid is a failsafe if that ever happens.

__________________
Proud owner of ....
1971 280SE W108
1979 300SD W116
1983 300D W123
1975 Ironhead Sportster chopper
1987 GMC 3/4 ton 4X4 Diesel
1989 Honda Civic (Heavily modified)
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Section 609 MVAC Certified
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