Mechanics...help me with oil pressure gauge

Discussion in 'Bad Dog Cafe' started by charlie chitlin, Nov 7, 2019 at 12:25 PM.

  1. charlie chitlin

    charlie chitlin Doctor of Teleocity Silver Supporter

    Age:
    57
    Posts:
    14,001
    Joined:
    Mar 17, 2003
    Location:
    Spring City, Pa
    Bought the $30 budget one.
    I know...but it SHOULD work anyway!
    Screw the adapter into the block, pop on the quick connect, fire it up... nothing.
    Same on another vehicle.
    Find tools to work on new tool.
    Grrrr.
    Put air hose in gauge alone.
    Needle moves.
    Check.
    Can NOT get air to go through hose.
    Remove little Schrader valve core from hose...now hose is hollow and air moves through it freely.
    Try a different valve core...same problem.
    Pressure hits this valve from outside and is obviously meant to push it open (unlike in an inner tube where pressure holds it closed).
    So...the 90+ psi from my air hose will not push that little valve open and let pressure get to the gauge.
    WTF?
    There's something going on here that I'm not getting.
     
  2. Uncle Bob

    Uncle Bob Tele-Meister

    Posts:
    498
    Joined:
    Mar 5, 2017
    Location:
    West Virginia
    The oil pressure gauges (both cheap and expensive) I've installed don't have a valve in the line, just a thin line that uses a compression fitting on the block and gauge. I don't understand why it has a valve in the line.
     
    boris bubbanov and telemnemonics like this.
  3. PlainAllman

    PlainAllman Tele-Holic

    Age:
    44
    Posts:
    659
    Joined:
    Feb 12, 2019
    Location:
    Van Zandt Co, Texas
    Maybe your supposed to remove the valve core before installing? The core may just be there to keep out moisture and debris. Is the fitting reversed possibly?
     
    Shuster, Andy B and telemnemonics like this.
  4. telemnemonics

    telemnemonics Doctor of Teleocity Ad Free Member

    Age:
    60
    Posts:
    17,273
    Joined:
    Mar 2, 2010
    Location:
    Maine
    Where is the block tapped for a gauge?
    Is the location a pressurized oil reservoir?
    Oil flowing to the heads etc might not be under pressure.
    Like the water that coming of the faucet is no longer under pressure.
    Not really sure here.
     
  5. charlie chitlin

    charlie chitlin Doctor of Teleocity Silver Supporter

    Age:
    57
    Posts:
    14,001
    Joined:
    Mar 17, 2003
    Location:
    Spring City, Pa
    It's not an installation, it's a tester.
    Shoulda been more clear.
    You take out the switch/sender and screw it in to check the pressure.
    I work on tractors, so everything is like 1950s cars.
    Switch/sender either in the block or on/near the oil filter housing.
    I'm thinking the valve might just help get a constant reading that will keep the gauge pressurized even after shutting down the motor.
    I'll probably try taking it out.
     
  6. telemnemonics

    telemnemonics Doctor of Teleocity Ad Free Member

    Age:
    60
    Posts:
    17,273
    Joined:
    Mar 2, 2010
    Location:
    Maine
    Hmmm, if it’s a sensor to an idiot light I’m not sure that’s universally connected to the pressurized portion of the oiling system.
    Might be but might also only sense that no oil is flowing through a passage that doesn’t actually have pressure in it, or not the high pressure found at the pump.
     
  7. dogmeat

    dogmeat Tele-Afflicted

    Age:
    68
    Posts:
    1,083
    Joined:
    Oct 12, 2017
    Location:
    Alaska
    the schrader valve is installed in the end of cylinder compression testers because it needs to trap a column of air in the hose to get an accurate number. otherwise, the reading would be low because the extra volume (added by the hose) affects the compression ratio. testing cylinders you have pressures well over 100psi

    an oil pressure gauge doesn't need, and shouldn't have a schrader
     
    telemnemonics likes this.
  8. telemnemonics

    telemnemonics Doctor of Teleocity Ad Free Member

    Age:
    60
    Posts:
    17,273
    Joined:
    Mar 2, 2010
    Location:
    Maine
    Might be worth going to a car brand forum to find out what the sensor does and if that location will work with your gauge.
    Lots of hobby mechanic info like here with our brand.
     
  9. telemnemonics

    telemnemonics Doctor of Teleocity Ad Free Member

    Age:
    60
    Posts:
    17,273
    Joined:
    Mar 2, 2010
    Location:
    Maine
    Yeah that kind of gauge set up as a compression tester certainly needs that valve to hold the reading.
     
  10. D'tar

    D'tar Friend of Leo's

    Posts:
    2,202
    Joined:
    Jan 11, 2013
    Location:
    WNY
    The fitting on the end of the hose should open the valve as it is connected. The gauge may have the same valve on it. If it's not doing what you want. "Make it". I would remove the valve core from the fitting and the gauge if all you need to do is get a quick oil pressure reading. 20191107_154355.jpg
     
  11. charlie chitlin

    charlie chitlin Doctor of Teleocity Silver Supporter

    Age:
    57
    Posts:
    14,001
    Joined:
    Mar 17, 2003
    Location:
    Spring City, Pa
    And...it's OK for oil to get to the gauge itself...inside the gauge?
    I can't believe I've been doing mechanics forever and never used an oil pressure gauge.
    Compression gauge...yeah...hundreds of times.
     
  12. MarkieMark

    MarkieMark Tele-Meister

    Age:
    59
    Posts:
    114
    Joined:
    May 7, 2016
    Location:
    Eastern USA
    Four and a half decades as a master auto mechanic, and I have never once seen an oil pressure tester with a Shrader valve.
    Just adapter, hose and guage. Maybe a fancy one with a quick disconnect coupler.

    And I have no clue what our friend from Maine is going on about. If you remove the stock sender/switch thats an oil pressure galley. Period.

    Whatcha working on?
    Whats the symptom?
    How can I help?
     
    rz350, telemnemonics and dogmeat like this.
  13. dogmeat

    dogmeat Tele-Afflicted

    Age:
    68
    Posts:
    1,083
    Joined:
    Oct 12, 2017
    Location:
    Alaska
    there shouldn't be any flow into the gauge...unless it's broken, its a dead end. even if there was some liquid in there it'll drain back out. 40+ years A&P/AI aircraft mech
     
  14. charlie chitlin

    charlie chitlin Doctor of Teleocity Silver Supporter

    Age:
    57
    Posts:
    14,001
    Joined:
    Mar 17, 2003
    Location:
    Spring City, Pa
    Right...duh...thanks.
    The gauge has variously sized/threaded fittings that go into the block (in this case) and the hose snaps on with a quick connect.
    Just downstream, where the quick connect attaches, is a schrader valve core.
    I assume the pressure is supposed to push it open, but it doesn't.

    The machine is a New Holland diesel skid steer.
    The oil light goes on at seemingly-random times and shuts the machine down.
    I strongly suspect an intermittent short somewhere between the sender and the dash.
    This machine is critical to the farm and I need to get it back in service.
    I don't mind bypassing the pressure sender circuit until I can fix it properly, but I want to be dead sure I don't have an actual low oil pressure situation.
     
    boris bubbanov and telemnemonics like this.
  15. bondoman

    bondoman Tele-Meister

    Age:
    28
    Posts:
    307
    Joined:
    Nov 10, 2018
    Location:
    vallejo ca
    First off you don't want any air in the line to the gage. Air compresses whereas oil will not. So even if you did get a reading it would be incorrect. New Holland huh? Wouldn't surprise me if it didn't have an oil pump going south. Worked as a mechanic for a New Holland dealership for 10 years. Have an old 3020 in the fleet at the moment. Biggest POS we have. Work for a county government these days.
     
    telemnemonics likes this.
  16. Pete Baker

    Pete Baker Tele-Meister

    Age:
    49
    Posts:
    222
    Joined:
    Aug 16, 2006
    Location:
    Maryland
    This may sound obvious, and probably isn't the case, but maybe the New Holland isn't making any oil pressure. Have you tried the gauge on a different engine?
     
    getbent and boris bubbanov like this.
  17. charlie chitlin

    charlie chitlin Doctor of Teleocity Silver Supporter

    Age:
    57
    Posts:
    14,001
    Joined:
    Mar 17, 2003
    Location:
    Spring City, Pa
    Yes...
     
  18. dogmeat

    dogmeat Tele-Afflicted

    Age:
    68
    Posts:
    1,083
    Joined:
    Oct 12, 2017
    Location:
    Alaska
    air in the line will compress, and the pressure will be the same as whatever it source is. if the source is not steady, the needle will fluctuate

    and ya, may have an oil delivery problem. crack the line and crank the engine & see if oil comes out. install the gauge with no Schrader valve, the pressure may be too low ot open it. thats all I got
     
  19. charlie chitlin

    charlie chitlin Doctor of Teleocity Silver Supporter

    Age:
    57
    Posts:
    14,001
    Joined:
    Mar 17, 2003
    Location:
    Spring City, Pa
    I cracked the line...plenty squirted out.
    I'm gonna pull the valve core.
     
    getbent likes this.
  20. schmee

    schmee Poster Extraordinaire

    Posts:
    7,459
    Joined:
    Jun 2, 2003
    Location:
    northwest
    Well, it's been ages but I think oil flows right into a normal old school oil gauge ... into the "Bourdon tube" inside the gage. Not sure air in there is good.. air is compressible... but I guess eventually it evens out.
    Old tractors probably have very low oil pressure, so not sure it will register.?
     
IMPORTANT: Treat everyone here with respect, no matter how difficult!
No sex, drug, political, religion or hate discussion permitted here.


  1. This site uses cookies to help personalise content, tailor your experience and to keep you logged in if you register.
    By continuing to use this site, you are consenting to our use of cookies.