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FahrverSprinten
02-25-2015, 12:12 AM
Greetings, Fellow Sprinters,

Not long ago I installed a new vacuum solenoid in my 2003 3500. When I shut the engine down I can hear the residual vacuum being bled off through the little filter behind the heater. It makes a gurgling sound like someone slurping the dregs of a milkshake through a straw. The sound lasts for about 5 minutes.

The service manual confirms that in its OFF state the vacuum signal is open to the atmosphere, but my question is whether that opening to atmosphere should take so long? Since the solenoid is controlled by a PWM signal, I would imagine that the vacuum modulation would be a fairly rapid affair. The filter passes air freely when I suck or blow through it.

So, my question is: Is this slow bleeding indicative of a faulty solenoid? :thinking:

Thanks in advance for any insights you can share.
Marc

surlyoldbill
02-25-2015, 12:56 AM
I hear a high pitch sound of air when I shut off, like air coming out of a tightly held balloon opening. Solenoid woks fine.

Also, if the solenoid was bad, you wouldn't have any boost pressure.

EZoilburner
02-25-2015, 01:08 PM
The vacuum solenoid can open the loop routed to the turbo actuator (02-03 that I know) and open close the veins as needed (go pedal further, high rpms) The canister should have a little filter to keep dirt and things from getting stuck inside it. If the vacuum solenoid did not work You would have no boost.

FahrverSprinten
02-25-2015, 08:42 PM
Thanks, Bill and EZ. I do indeed have boost, but only until I go over 60 MPH for some (undetermined) period of time, AND with uphill grades and/or headwinds. For example, I can drive a certain 20 mile stretch of freeway in one direction at 70 MPH with no problem, but making the same return trip will cause the turbo to shut down with no codes or MIL. A key cycle restores full driveability.

So, I am wondering whether a partial blockage inside the solenoid might cause the ECU to cut off the signal to the solenoid. I'm going outside to fiddle with it yet again. :idunno:

surlyoldbill
02-25-2015, 10:12 PM
I kind of have the same thing going right now, but haven't been able to link driving conditions to no boost. In fact, I didn't have it at all today...yet. I changed oil yesterday, but that shouldn't make any difference. I also hit "clear all codes" on my OBD program, even though it showed no codes.

Tooth Fairy
02-26-2015, 07:56 AM
Thanks, Bill and EZ. I do indeed have boost, but only until I go over 60 MPH for some (undetermined) period of time, AND with uphill grades and/or headwinds. For example, I can drive a certain 20 mile stretch of freeway in one direction at 70 MPH with no problem, but making the same return trip will cause the turbo to shut down with no codes or MIL. A key cycle restores full driveability.

So, I am wondering whether a partial blockage inside the solenoid might cause the ECU to cut off the signal to the solenoid. I'm going outside to fiddle with it yet again. :idunno:

Check for a vacuum leak, I had a similar issue and it turned out to be a vacuum leak.

4x4sprintcamp
02-26-2015, 07:57 PM
Is this the part you are talking about by any chance?

http://pages.ebay.com/link/?nav=item.view&alt=web&id=201106663173

The reason I ask is that I have exactly the same symptoms but I also have a problem with the vacuum not being strong enough for my 4x4 to engage/disengage. And I Beleive this controls all parts?

surlyoldbill
02-26-2015, 09:28 PM
The turbo shut down might be some sort of partial LHM. It may be totally unrelated to the turbo itself. Possible weird sensor reading from the IAT, MAF, EGR, etc. or maybe even fuel pressure sensor. Since it does it when you are under load (uphill, headwind, etc.) it may have something to do with fuel or air supply. Have you changed your air and fuel filters lately?

FahrverSprinten
02-26-2015, 10:58 PM
Bill, you are indeed right! It turns out that the MAF sensor I had in the van was not the correct one. A while back I learned that the Sprinter shares the MAF with certain Mercedes cars between 1994 and 1999. I carelessly chose the wrong wreck to pull my replacement from.:doh: Yesterday I replaced it with the right one and the turbo shutdown episodes ended.:bounce:

4x4sprintcamp: The part I am referring to is the controller for the turbo's variable vanes. It lives under the airbox near the turbo. Your link is to the vacuum pump, which creates the vacuum on which all the systems depend. Have you examined the vacuum lines for leaks? It seems Sprinters are vulnerable to that kind of wear.

4x4sprintcamp
02-27-2015, 06:03 AM
Ok thanks I will check that out! Can you post a part number for the turbo controller please.

FahrverSprinten
02-27-2015, 07:08 AM
Turbo pressure regulator, vacuum transducer, vacuum solenoid, etc.

Dodge part number: 05080371AA
Mercedes part number: A 000 545 05 27

Helpful link: http://www.mercedes.gen.in/WP35/mercedes-sprinter-turbo-limp-home-los-diagnosis-fault-finding/