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Oil Pressure Problem

Discussion in '"Stock" Alpine' started by Scotty, Jan 10, 2022.

  1. RootesRooter

    RootesRooter Platinum Level Sponsor

    Scotty - Well, like you said, you've been paying more attention to the temp gauge until recently. Fresh results from Hartmandm's tests are needed to see if you've got a sticking PRV.
  2. spmdr

    spmdr Donation Time

    I have issues with the video as well.

    First off, the oil PRL is not a magic SOURCE of oil pressure.

    If the PRL is closed, adding pressure to the PRL will not add engine oil pressure.

    The main reason for the PRL is to bleed of excess oil pressure.

    My main problem with the video is the suggestion that the PRL be set at IDLE.


    The PRV has at least two functions.

    1) bleed off excess oil pressure.

    2) bleed off excess Volume of COLD oil.

    You have to be careful with the PRV that you don't reduce it's volume flow with cold oil.

    I have had issues with PRV sticking Open AND sticking Closed!

    I'm tempted to try a Ball in place of the Piston.

    Last edited: Jan 16, 2022
    Shannon Boal likes this.
  3. alpine_64

    alpine_64 Donation Time

    Dan.. Speak with Jartid and also Steve S... This was discussed a couple years back, iirc maybe jarrid had a first pass at it? @RootesRacer ??
  4. Tim R

    Tim R Silver Level Sponsor

    Your comments are interesting, as you say the PRV is there to prevent excessive pressure, splitting filters causing leaks etc etc.

    It is true that adding pressure to a closed PRV won't increase oil pressure BUT increasing the spring pressure so that higher oil pressure is required for it to lift and release does.

    I'm not sure why setting the pressure at idle is wrong? If you increase pressure at idle it stays proportionally increased as revs rise all the way through the range. I claim no specialist expertise on this but this modification has been done on numerous cars over a very long period without any issues that I am aware of.

    Your idea of a ball could be an ideal solution and if you were to produce some you would undoubtedly find customers.

    When your PRV stuck in the closed position, did it cause you any damage? (I've read of people having oil filters burst)

    Best Wishes,

    Tim R
  5. Scotty

    Scotty Platinum Level Sponsor

    So as it turns out, I don't have a stuck anything. What I have is a carb problem. Here's the deal:

    I took the advice given and adjusted the Weber 32/36 from SS back to stock spec. Bang! The oil pressure went back up to 40 on a cold start and stayed there. I noticed that if I lean the Weber too much, my Temp Gauge rises like mad and I will overheat if it let it, so my issue is this damn Weber that either runs rich but likes that or starves and starts to get too hot. What am I doing wrong here? I've read the paperwork on how to tune this thing and I simply can't figure it out.

    And yes, the 1725 fires up from stone cold and sits at 40 on the Oil Pressure Gauge. I'll drive it when my hand is better and see what the gauge does and answer a few more questions.
    Last edited: Jan 22, 2022 at 2:42 AM
  6. spmdr

    spmdr Donation Time

    This is why NOT to set the oil pressure with the PRV at Idle.

    At idle, the oil pump is turning at a slow speed, half the speed of the crank shaft.

    The oil pump is a positive displacement pump, at slow speeds, low volume.

    If you adjust the pressure at idle, chances are you will raising the pressure

    only by reducing the VOLUME the PRV will flow.

    What you should do AFTER adjusting the PRV, is remove it and verify the piston

    MOVES all the way open.

    IF the piston movement is limited by the spring being too far compressed (coil bind),

    You NEED to replace the spring with a stiffer one that lets the piston move all the way open.

    Regarding the PRV sticking closed, I recently noticed it on the Weekend Racer when I

    was at high RPM in 3rd gear, the oil gauge was near 100 psi !!

    It was at Fontana at the end of a race. I immediately dropped the throttle and clutched it at the same time.

    No problems found and I have not had that problem since.
    Last edited: Jan 22, 2022 at 11:21 AM
    Tim R likes this.
  7. RootesRooter

    RootesRooter Platinum Level Sponsor

    I've had my oil psi noticeably drop once while the temperature was almost pegged due to running up Pikes Peak on a very hot day. But I'm not sure if running too lean with the engine in normal temperature range could cause the kind of drop you experienced. Very odd circumstances. Looking forward to reading your test results!

    Regardless, I hope you didn't run it long or at high speeds while it was badly starving. Piston melt-down is a frequent consequence.
    Last edited: Jan 22, 2022 at 4:47 PM

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