Scary oil pressure issue - help!!

Discussion in 'Engine Topic' started by lumpy12, Feb 1, 2014.

  1. lumpy12

    lumpy12 Veteran Member Lifetime Gold Member

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    So today I jumped in to see what I could find.

    - I changed out the bypass assembly with a new one. The one that was there didn't have a gasket. Both had the same feeling tension in the springs but the old one seemed gummy on what looks like a brass screen part.
    - Used a Wix 51061 which is almost an inch longer than the Wix 51069 filter I had before. Couldn't find anything wrong with the old filter
    - Drained the oil and probed around in the pan. Pickup is in place and there feels like a good inch of distance between it and the bottom of the pan. I think more actually
    - put 5qts of 10-40 in and fired her up (same oil as last time)
    - went straight to 50# oil pressure and I warmed it up.
    - shut it down to verify oil level on my dipstick and went for a ride between raindrops.

    I found the pressure drop still occurs but less of a drop and happens at a higher RPM. Doesn't happen now until over 4000RPM and it only goes down to about 30-35#

    I didn't mount the second oil pressure gauge and didn't chase the current oil pressure gauge's ground. Unfortunately the car has an Autometer "Nexus" gauge package which uses a common harness and ground. It's a pain in the ass to trace it and since the other gauges work well and the symptoms have changed, I'm not inclined to think it's the ground at the moment.

    So the only variables in my mind are the bigger filter area of the new filter, the new bypass assembly, and it's gasket.

    ->I wonder if a racing oil filter with less restriction would have the same behavior
    ->I wonder what would happen with a bypass eliminator

    I'm very happy to have my pickup still in place and what I believe is enough clearance between it and the pan ;)

    I'd love to hear some thoughts :)

    Tim
     
  2. nasstzz

    nasstzz Veteran Member

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    While cruising along 50ish if you accelerate does the oil pressure fall at all, then rebound
     
  3. lumpy12

    lumpy12 Veteran Member Lifetime Gold Member

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    I can't remember noticing that. I know that throwing it around in tight twisty corners it doesn't drop, unless the RPM's are up
     
  4. newschool72

    newschool72 Veteran Member

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    An inch or more clearance seems excessive . I have always made it a priority to have the pickup at 1/4" or so, with every SBC build Ive done. With the pickup sitting that high, it could very well be pumping the pan low at higher RPMs and sucking some air, lowering the pressure.
     
  5. COPO

    COPO Veteran Member Lifetime Gold Member

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    Last edited: Feb 8, 2014
  6. lumpy12

    lumpy12 Veteran Member Lifetime Gold Member

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    Yeah, it could be too high. Sticking a screwdriver in there sure isn't an accurate way to check but I'd guess there's about an inch gap. Maybe more, maybe less ....
     
  7. lumpy12

    lumpy12 Veteran Member Lifetime Gold Member

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    That's what I thought, so last weekend I'd added an extra quart and it made no change. I've found a lot of threads/posts with Google of people having the same problem with small blocks, yet no consistent solution.

    add an extra quart
    one quart underfilled
    changing to a stock pump
    moving the pickup closer to the bottom
    moving the pickup a bit higher
    blocking the bypass
    lighter oil
    heavier oil
    oil restrictors
    bigger/better pan

    For me I think the real fix is the appropriate pan and pickup set properly. I'm just not motivated at all to do that yet!

    Tim
     
  8. COPO

    COPO Veteran Member Lifetime Gold Member

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    I'd like to see how a mechanical gauge would react. Just think, if you only had the oil dummy light, then you
    wouldn't have a problem.
     
    Last edited: Feb 9, 2014
  9. Dave Nelson

    Dave Nelson Veteran Member

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    This !!
     
  10. captaincog

    captaincog New Member

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    My 71 has a mechanical gauge and does the same thing and while taking her out for a spin yesterday I was thinking the same thing. I hear no odd noises and she runs like a dream except if I look at that damned oil gauge for a little too long at the wrong time. I am just going to drive her and live with my issue until I see an adequate finding that shows where to really go to solve the problem....if there is even one to really begin with.
     

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