Mk2 '89 8v oil pressure switch issues .. please help

Discussion in '8-valve' started by slimwadey, Mar 4, 2012.

  1. slimwadey Paid Member Paid Member

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    Hi
    I have a bit of an issue with the oil light on my GTI flashing
    Just before i bough my car the previous owner replaced two oil pressure switches on the engine due to them leaking, he used VAG parts too, a black one and white one.
    One sits on the oil filter housing closest to the block, The other is on the right hand side of the head near the front edge
    I can remember which is where right now
    The car runs and idles fine and i let the oil temp get up to around 80c. the oil light stays off, if i rev at all, even a tiny bit the light flashes, once back to idle the light goes off
    So i used an oil pressure tester to check the pressure before i seized it up !

    This pic is from the lower point on the filter housing
    A smidge under 3.0bar, Pretty good pressure for a 145,000 mile engine

    [​IMG]

    This is from the Cylinder head sensor hole


    [​IMG]

    Still pretty good

    So i was wondering whats going on
    Is there another sensor i can replace
    I tried to swap the sensors with each other incase he had got them mixed up but it makes no difference which hole they go in
    I have also replaced my ECU due to another matter and this was a problem before and after so its not that either

    Any ideas ?
    Slim
     
    Last edited by a moderator: Mar 4, 2012
  2. slimwadey Paid Member Paid Member

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    I have only checked the wiring in the engine bay and it looks fine, although i have not atually electrically tested it just visual

    Slim
     
  3. slimwadey Paid Member Paid Member

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    The car is at work so i wil have a play tomorrow after i have sorted the (age old) gear linkage issue

    Thanks
     
  4. EZ_Pete

    EZ_Pete Forum Junkie

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    I think your problem is most likely to be the black switch you mention. I think the PO was sold the wrong switch, and it is operating in the wrong way (normally open instead of normally closed). What is the part number and rating of this black one you’ve got?

    The following is a slight edit of something I wrote a while back.

    White switch (056 919 081E or equivalent. Edit: superceded by 056 919 081 apparently) with yellow wire is the one that does the buzzer and warning light, if the oil pressure is below 1.8 bar and the revs >2000ish. Located on top of oil filter housing.

    Brown switch (056 919 081C or equivalent. Edit: superceded by 028 919 081H, which is blue and 0.25 bar rated) with blue/black wire is the one that just puts the warning light on, at any time that the oil pressure is less than 0.3 bar (including when ignition is on, but engine not running). This switch sits in the (UK) nearside end of the head at the end of the main head oil gallery on 8v engines.

    They operate electrically in opposite ways.
    Wherever I use the term 'ground', I mean 0V/battery negative/chassis ground/earth.

    For the brown switch, when oil pressure is lower than its 0.3 bar threshold, the blue/black wire is shorted to ground by the switch. When the pressure is above 0.3 bar the wire is open-circuit, not connected to anything electrically at the engine end.

    To test the switch, disconnect the blue/black wire, then check the resistance to ground from the spade terminal of the switch, in situ, with the engine off, then running. Should be zero Ohms and infinite respectively.

    To test the wiring and warning light/circuit, disconnect the blue/black wire from the switch, start engine, then connect the blue/black wire to a good engine/chassis ground. The warning light should illuminate.



    For the white switch, when there is low oil pressure, the yellow wire is open circuit, not connected to anything electrically at its engine end. When the oil pressure is above the 1.8 bar threshold, the wire becomes connected to ground by the switch.

    To test the switch, disconnect the yellow wire, then check the resistance to ground from the spade terminal of the switch, in situ, with the engine off, then running. Should be infinity and zero Ohms respectively. The opposite of what the other one did. May need just a tiny raise of revs above idle to flick it into the zero Ohms state; oil pressure may be rather marginal if this is the case.

    To test the wiring and buzzer/circuit, just disconnect the yellow wire from the switch, rev the engine to more than 2000 rpm for a few seconds, and the buzzer and light should come on.

    :)
     
    Last edited: Mar 5, 2012
    TomAKL likes this.
  5. slimwadey Paid Member Paid Member

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    I will take all this info into consideration and do the checks tomorrow
    Thanks a lot
    Steve
     
  6. slimwadey Paid Member Paid Member

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    Ok i have removed both switches
    The black one was in the head at the nearside end was connected with a Blue/Black wire
    Part No 068919081D 1.2-1.6 Bar
    The white switch was in the lower position connected to a yellow wire
    Part No 0569919081 1.6-2.0 bar <NO 'E' code after number

    There is another sensor on the filter housing in front of the other that has a green/black wire attached, is this relevant ?

    I have spoken to VW and they have superseded the part No of your brown switch Switch from 056 919 081C to 028 919 081 H

    So it seems i have the incorrect 'Black' switch rather than the correct brown switch, and they were also fitted in the wrong places


    Steve
     
  7. EZ_Pete

    EZ_Pete Forum Junkie

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    Steve, I'm pretty sure you have the correct white switch then, I seem to remember the mighty rubjonny posting fairly recently that 056 919 081 had superceded 056 919 081E.

    The black one definitely sounds wrong; but the blue one (028 919 081H) that VW have suggested should sort you out for the head position.

    Other sensor with green/black wire, oil temperature I think.
     
  8. slimwadey Paid Member Paid Member

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    I'll get the Blue one ordered and see how things go
    Thanks for your help i appreciate it

    Steve
     
  9. EZ_Pete

    EZ_Pete Forum Junkie

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    No problem.
    Please do post a 'thread closer' if the blue switch does solve it. Always handy for people searching and finding the thread later, to know what worked. :thumbup:
     
  10. slimwadey Paid Member Paid Member

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    Ok once i have ordered the sensor i will report back
    Now i just have to remove the oil cooler housing as it has a small leak between it and the main housing, never done this before, is it easy ?

    Steve
     
  11. slimwadey Paid Member Paid Member

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    I'm happy to report that after purchasing the correct blue oil pressure sensor
    All is well
    No more problems with the oil pressure light
    Thanks EZ Pete

    THIS THREAD CAN NOW BE CLOSED PROBLEM FIXED
     
  12. Farmerchris

    Farmerchris Paid Member Paid Member

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    This thread has saved me a lot of head scratching. Thanks for the useful info everyone who commented.

    thread resurrection :thumbup:
     
  13. Simon Peter Dodgson Forum Member

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    Yes thank you for that info I ordered the black sender from TPS. It was actually brown now blue
    Mk2 golf gti old brown oil pressure switch leaking oil https://imgur.com/gallery/DxQBJB1
     

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