Every time I start my C220 I hear the vacuum pump in the rear run for about 4-5 minutes. I assume I have a vacuum leak. How often does this pump run if you have a car without a vacuum leak? Where is the first place to look?
Vacuum Leak?
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Is this the 1995 C220?
If it is, the vacuum pump is located behind trim on right side of boot/trunk, follow sound to locate.
The vacuum pump shouldn’t run for 5 minutes, it has a time out, it should cut out automatically after about 20 seconds so as to prevent damage to the pump motor.
Inspect the electric plugs to the pump and ensure that the are clean and there is no rust.
Open the pump and inspect the PCB for damage/broken solder joints.
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Even if you had a leak, the pump shouldn’t run for 5 minutes.
Dec
If it is, the vacuum pump is located behind trim on right side of boot/trunk, follow sound to locate.
The vacuum pump shouldn’t run for 5 minutes, it has a time out, it should cut out automatically after about 20 seconds so as to prevent damage to the pump motor.
Inspect the electric plugs to the pump and ensure that the are clean and there is no rust.
Open the pump and inspect the PCB for damage/broken solder joints.
Even if you had a leak, the pump shouldn’t run for 5 minutes.
Dec
Thanks C180w for the pictures and quick response. This is certainly useful information. It doesn't run continuously for 5 minutes. It cycles for about 5-10 seconds and then shuts down. It then cycles again immediately. This cycling process takes place for about 5 minutes until it finally shuts off.
The car begins the pump cycling as soon as I turn on the ignition. I have done a search and found some excellent posts on this subject. One thing I have noticed is that there is a crack at the metal ball on the vacuum distributer block in the engine compartment under the plastic panel where the ECU is located. Viewing other posts on this problem, I notice that this is a common failure and may be contributing to the leak. I am curious on how the vacuum distributor block operates. It appears to have two check valves on it to prevent backflow into the manifold. Does anyone know exactly how this vacuum block operates?
Some explanation here… https://www.justanswer.com/mercedes/74z7c-c220-1995-mercedes-c220-w202-vacuum-issues.html
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I have replaced the vacuum distributor block located in the engine compartment next to the ECU. It had the small crack next to the ball which is a common failure. I would like to check the individual lines with my mityvac. There are two black/grey lines which go to the automatic transmission. One is for the upshift delay vacuum actuator and one is for the Automatic transmission vacuum reservoir. Is it OK to check these with the Mityvac. I am curious why there are two lines? Where is the reservoir located?
Reservoir is apparently hidden behind the fender on the same side as the block. I've never seen it, I'm just going off what I heard. You can mityvac everything, just don't pass 15" Hg of vacuum (or half-way on whatever units you are using).
Hi RES, you sent me a private message yesterday and below the line was my response.
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The VACUUM RESERVOIR is located inside the driver side wing/fender, see image here… 98 MERCEDES BENZ C230 W202 VACUUM RESERVOIR 2108050119 OEM | eBay ... follow the green vacuum tube from the manifold block ( Or Pneumatic distributor connector), picture below.
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The link I gave you in my last poste details the where each vacuum line goes to.
Quote “Customer :
hook up is as follows..
Port 1 - Unused
Port 2 - White from Vac pump in trunk
Port 3 - Unused
Port 4 - Black / White to bottom of Vac Res in pass fender
Port 5 - Black / White to Kick Down Relay near OVP relay
Port 6 - Red / Black to top of Vac Res in Passenger fender
Port 7 - Green to HVAC Valve block in passenger dash
Port P - White from intake manifold”
From the vacuum pump, all the Yellow lines go to doors, fuel flap and trunk lock. The Grey Or White line goes to the engine bay.
If there is a leak in the manifold block (crack at the metal ball) then you must fix or replace that first otherwise you are wasting your time checking other stuff.
Dec
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The VACUUM RESERVOIR is located inside the driver side wing/fender, see image here… 98 MERCEDES BENZ C230 W202 VACUUM RESERVOIR 2108050119 OEM | eBay ... follow the green vacuum tube from the manifold block ( Or Pneumatic distributor connector), picture below.
The link I gave you in my last poste details the where each vacuum line goes to.
Quote “Customer :
hook up is as follows..
Port 1 - Unused
Port 2 - White from Vac pump in trunk
Port 3 - Unused
Port 4 - Black / White to bottom of Vac Res in pass fender
Port 5 - Black / White to Kick Down Relay near OVP relay
Port 6 - Red / Black to top of Vac Res in Passenger fender
Port 7 - Green to HVAC Valve block in passenger dash
Port P - White from intake manifold”
From the vacuum pump, all the Yellow lines go to doors, fuel flap and trunk lock. The Grey Or White line goes to the engine bay.
If there is a leak in the manifold block (crack at the metal ball) then you must fix or replace that first otherwise you are wasting your time checking other stuff.
Dec
I have traced the red/gray line and the black/grey line to the vacuum reservoir in the right fender well. I also checked these two lines with the mityvac and they appear to hold vacuum. I was confused on these reservoirs. I thought there was two since there are two vacuum lines going to them. When I checked each one of them for vacuum they appeared to be independent. I am now thinking that the reservoir has two independent chambers, one for the A/C and one for the Transmission upshift. From the schematic I show below of the vacuum distributer block, it appears that the vacuum pump (PSE) only supplies vacuum to the locks and to the A/C system. The transmission upshift is isolated by a check valve and only gets vacuum from the engine manifold.
http://www.benzworld.org/forums/attachment.php?attachmentid=2273777&stc=1&d=1506379611
http://www.benzworld.org/forums/attachment.php?attachmentid=2273777&stc=1&d=1506379611
Attachments
Have you considered the fault might be within the vacuum pump, if your pump is the same as the one described in the post below then there might be an issue with the way the pump is switched off.
See from post #31 here… r129 central locking problem | Page 2 | Mercedes-Benz Owners' Forums
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See from post #31 here… r129 central locking problem | Page 2 | Mercedes-Benz Owners' Forums
Dec
That is a possibility. I think I can check the pump "turn off" by disconnecting the white line from the pump at the vacuum distributor block and temporarily plugging it with my finger while some one turns on the ignition. The pump should shut off immediately. Do you agree that the vacuum reservoir has two chambers?
I don’t know enough about the vacuum reservoir so no idea if it has 2 chambers.
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