Question about 1992 Mercedes-Benz Mercedes Benz 300 Class
Can i please see a vacuum system diagram?
Big breather from valve cover to air cleaner, the small vac line runs from there to the FPR.
These next are standing in front of the car:
Intake manifold lower outer runs to EZL
Intake manifold lower inner (right side) goes to switchover vac valve on driver fender. The other side of this vac valve goes to the throttle body
Intake manifold lower inner (left side) goes to switchover vac valves on passenger side fender. These then go back to the EGR valve once making a loop under the distributor cap for whatever reason.
Intake manifold rear runs to a 'three' way valve (or 'Y' connector) on the secondary firewall. This is usually a vac leak.
Posted on Nov 17, 2013
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Posted on Jan 02, 2017
neto 190D: You are asking about a vacuum diaphragm?
I'm going to take a WAG.. Your engine won't shut
down with the key?
If so, he is the way you find out:
In your injection pump, the vacuum diaphragm which kills the engine is the one which has the fitting pointing parallel to the ground.
The vacuum line which serves it is a brown/blue
To check the system, first check for vacuum in the line. Run the engine for a minute or so. Cap off the brown/blue line.
Turn the ignition switch off and then with hose in hand, uncap it and you should hear a hissing sound. If you have a vacuum guage, obviously, use it for the test, you need a minimum of 10 inches to kill it.
To test the pump diaphragm, you can rig a vacuum line to a known vacuum source close to the main "T". Run the engine and with the line connected to the diaphragm, connect it to the good vacuum source, if it kill the engine, the diaphragm is good. If you have a hand vacuum pump it would be more ideal, because you could check the diaphragm for small leaks.
If the diaphragm is bad, it is easy to replace on the pump.
The shutoff diaphragm lists for $86.00
Is my shot in the dark correct?
Even though I am a Nissan Master tech, I also specialize in Mercedes-Benz and specifically Diesels, so if you need help, I'm here. I went through a few Mercedes Schools and have been swinging Iron in Mercedes since the 70's
I might be a little more informative than the public library.
Posted on Apr 24, 2009
First the sensor in the rear gearbox may be bad or corroded for sensing wheel speed. Also the engine wiring harness may be falling apart. From 1991-1995 the US made MB use biodegradable material on the wiring. When the insulation cracks you get shorts in the system. The same wires are in your EHA on the air inlet area. Check and replace as needed.
Posted on Jun 16, 2009
The check engine light is on for a reason. You need to pull the error codes, and resolve all of the issues indicated. Then the light will go off.
If a condition were to happen, and be intermittent, the light would go out....But your description appears to have a fault condition detected. It is better and less expensive to fix the issue(s).
Posted on Oct 10, 2009
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