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Broken PSE Pump???

Discussion in 'Electrics, Vacuum, Ignition and ECU' started by Sam Stoddard, Jul 5, 2020.

  1. Sam Stoddard

    Sam Stoddard Member

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    Your Mercedes:
    SL350/2003/3.7Lt
    Hey guys I’ve been having issue with my boot soft close and also the central locking not working. On my 2003 SL350 (R230)

    In another thread I went through everything I’ve done so far including sealing every single possible leak from the PSE to the boot actuator.

    I’ve also stripped down the pump and can’t see anything wrong inside.

    The PSE operates everything in the car correctly other than the soft close (it doesn’t cut out even when both micro switches in the boot actuator are sensing it closed.

    However after three times of the soft close working okay it stops and takes the central locking with it.

    I then disconnected the hose for the “HECK” port and blocked it up in the pump to fully check that it’s not further down the system. I activated the boot soft close with this hole blocked up and the pump still ran for 10secs +.

    Is this a software issue that can be fixed OR is it a broken pressure sensor in the “HECK” part of the PSE?

    What could I do to fix as I can’t afford a new PSE right now, especially if everything else on the pump functions correctly!

    please hellllppp
     
  2. star

    star Forum Supporter Authorised Forum Supporter

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    As mentioned in the other thread, if no leak is apparent, then the electrics in the pump fail, not sure what but a replacement pump fixes it.
     
  3. RhodieBill

    RhodieBill Senior Member

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    Your Mercedes:
    W208 CLK320 182U ALMANDINE-BLACK METALLIC
    Have you removed the Pump Assembly and checked the Pump and the Valve Assembly independently? The Valve Assembly can get blocked up with Carbon from the Self-Lubricating Vanes in the Rotary Pump.
    I had a simular problem on my S500, it would work a couple of times them blow the Fuse, (which is a Fail-Safe measure to stop the Motor from burning out).
    I removed the PSE Assembly and cleaned out all the tiny Airways in the Pump Manifold as well as the Valve Assembly itself. While I was at it I disassembled the Pump and gave it a good clean - putting it back together is a bit tricky, cleaned the Brushes with Mannol Electrical Cleaner Spray and re-installed it and it was fine after that.
    But it is doable all in a day, even though a lot of it was trial and error at the time.

    I did post the shenanigans on here at the time.

    Found it...... But if you read it you will see until I found the problem I was searching blind.....

    https://forums.mercedesclub.org.uk/index.php?threads/i-think-i-damaged-something.173458/

    Anyway, I doubt it helps, but it might. At least you know you are not alone...... Although I never had any more problems after managing to fix it with a lot of luck and help!
     
    Wighty likes this.
  4. LostKiwi

    LostKiwi Senior Member

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    When reassembling the pump you need to check the output pressure as you tighten it. If it doesn't reach the cut off pressure the motor won't stop.
    There's a good YouTube description here:


    Soft close takes a lot of pressure to operate. If soft close isn't working it suggests you're low on pressure.
     
    Wighty likes this.
  5. RhodieBill

    RhodieBill Senior Member

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    I just wish people would stop calling it a "Vacuum" Pump, because it ain't...!!! :mad:
    It was on the Older cars that used to work off the Engine Vacuum, but that was primarily for the Locks and Vent Controls.

    NB. And before anyone gets all twisted I was referring to the Video Heading.
     
  6. star

    star Forum Supporter Authorised Forum Supporter

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    It does draw a vacuum ;) if the rotor failed, then the whole system would fail and not just the soft close on the boot after a few operations.
     
  7. RhodieBill

    RhodieBill Senior Member

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    Of course every Pump draws a vacuum by default, that goes without saying. But the PSE Pumps primary objective is to Pump Air, not to create a Vacuum.
    It is statements like that which create confusion and misunderstanding for people that know nothing, or very little, about how the system works........
     
  8. OP
    Sam Stoddard

    Sam Stoddard Member

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    Hey guys an update... I’ve stripped the pump and found the tiny one way check valve on the pumps + pressure output is missing!

    could this be the reason for the lack of pressure build up?

    If so where can I get something to replace it?
     

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  9. LostKiwi

    LostKiwi Senior Member

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    Someone on here may have a knackered one perhaps. Steal the valve out of it.

    Alternatively a ball bearing and spring may work? I'm assuming it sits under the plastic tube connectors?.
     
  10. bluesl

    bluesl Member

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    The inlet pipe to the turbine has a very fine gauze to keep dirt out but on the outlet there is some sort of tiny disk, not sure what the purpose of it is, it is certainly not strong enough to control the pump pressure or act as some sort of non-return valve.

    I’ve hooked up my pump motor to a pressure gauge and at 12v, I get 2.9-3 bar. You need a hefty power supply to run it, the motor is drawing 10A or so and you should only run it for a few seconds because it’s dissipating 120W and never without a pressure load to keep the speed down and avoid the turbine self-destructing.

    The pump motor switches on and off to keep some pressure in the manifold, there’s a pressure sensor with adjustable contacts to set the pressure. If the pressure requirement is not met after a few seconds with an output port open, the PSE flags it as bad until it is cleared by a power reset. That’s why the boot self-close can give up and all the other functions continue to run. Keep in mind the PSE is permanently powered from the rear battery but should normally never operate if the manifold pressure is holding.

    That’s where I am with mine, it was blowing the 20A fuse but now it typically draws 6-10 A. Incidentally, Sealey sell a useful tool (TA125) which is an ammeter which plugs in in place of the fuse and has a peak reading ability to show the max current flowing when you, for example, lock the doors (about 6A) or close the boot (about 10A).
     

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