Oil pressure problem

Discussion in 'Big Block Cadillacs' started by richie49, Jun 27, 2018.

  1. richie49

    richie49 Member

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    Okay here goes. My 1976 500 in my corvair has started acting strange in regards to oil pressure. When cold has 55 to 60 psi at 1500 and 45 at idle of 700.When it warms up it starts droping.When warmed up at 180 to 190 temp the pressure drop to 18 or 20 at idle and 25 or so at 1500 to 2000 rpm.it might go to 30 to 35 if it revs up to 3000 rpm. Is there something i can look at besides a rebuild. The pump is stock .Would the spring in the pump be getting weak?

    Richard richie49
    PS I was following the tread on dissappearing oil pressure,but there no follow up on it.
     
  2. Ted in Olympia

    Ted in Olympia Well-Known Member

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    20-50 oil?
     
  3. richie49

    richie49 Member

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    I was running 20 50 and when the pressure started acting up I changed to sae 40 with zppe or whatever it called.

    Richard richie49
     
  4. Darius

    Darius Well-Known Member

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    How hot is it getting down Texas way???

    d
     
  5. Ted in Olympia

    Ted in Olympia Well-Known Member

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    20 at idle and 35 running is a fine oil pressure IMO, I don't think you have to worry

    But I have been known to put a small thin nut behind the bypass spring before and increased the oil pressure. If you do this, even temporary, and the oil pressure is the same than it tells you this is all that can happen. If the pressure increases than the bypass spring was weak, and I would leave the spacer in there. The hard part is getting the spring out with the motor mount in the way.

    Ted
     
  6. richie49

    richie49 Member

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    Darius
    Temp has gone down a little for today,its 91 degrees,has been in high 90's and but has index fills like 103.
    Ted
    The oil pressure is barily getting to 25 while driving around town at 30 to 40 mph. Im going to remove spring and try that.

    Richard richie49
     
  7. Darius

    Darius Well-Known Member

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    Ditto what Ted said.

    I've done the 'added nut' before and it worked for me. Hopefully it will cure your problem.

    bro. d
     
  8. one finger john

    one finger john Member

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    Sounds like possible bottom end bearings slowly going away. Look for glitter in the oil and oil filter.
    Best of luck, John
     
    SHAKEDOG, El Diablo and 8ad-f85 like this.
  9. PJ McCoy

    PJ McCoy Active Member

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    EEEEKKK!!!!! Lets all hope not. I know you are giving sound advice John, But for his sake I am hoping its something simple.
    I seen sparkling flakes in my oil. The first change after the new cam and lifters. A some less after the second change. It was changed less than 300 miles. The last oil change it looked OK but did a little bit but nothing like the first two had. All oil changes were early. My Speedo didnt work so I did it based of run hours and guessing.
    So EEEEKK for me too.
    PJ
     
  10. one finger john

    one finger john Member

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    Sparkles in the oil and filter aren't supposed to be there. Besides coming from rapid bearing wear, they can come from cam components going south, distributer gears (either dist or cam or a combo of both, although more likely dist.), valve springs moving around, a host of things that touch and aren't supposed to.
    If the same thing is happening with your engine, at least pull the filter and cut it open. Also don't drive your car until the filter circumcision has been performed.

    Quick like a bunny, do it. Then let us know what you find.

    John
     
  11. Red98422

    Red98422 New Member

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    I’m going to have to jump on the “glitter is bad” band wagon...someone please correct me if I’m wrong but IMO glitter=abrasives=not good for an engine especially if you have a tight clearance engine, I have recently taken my engine apart and the remants in the oil pan could’ve been used as bearing filler putty...pretty close to my heart if you know what I mean.
     
  12. richie49

    richie49 Member

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    I changed oil and filter just before writing about it and didn't notice sparkies in the oil,but then I wasnt looking for that.I have the oil in a jug sealed up so I can look at it.It will be a week or so till I get to it.My daily driver 97 chevy pickup broke.The booster leaked andI have to replace it.Anyone who has replaced one on a 97 will know what I mean.
    I get back with everyone when I get back on it.

    Richard richie49
     
  13. PJ McCoy

    PJ McCoy Active Member

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    OH BOY
     
  14. richie49

    richie49 Member

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    Thats what I said..Oh Boy......Going to visit my son in San antonio tx for 4 th of July back on fri or sat, still got to finish truck, boosters on but dash is a mess..

    Richard richie49
     
  15. richie49

    richie49 Member

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    Havnt gotten back on the 500 yet.Going to try in the morning to see if the problem lies with the oil pump spring.

    Richard richie49
     
  16. richie49

    richie49 Member

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    Well I finally got to the 500 and changed out the spring from a spare motor oil pump.The oringnal spring didnt seem bad,hard to tell by looking.But the spring I put in was a little longer and added some washers.
    Took it for a spin and got it up to temp.At idle hot pressure was 20and running down the road at 40 mph it was 35 to 40 but when driving at 30 mph it was around 28 to 30 around that number. So I stopped and layed into hard and let it idle and the pressure went to 13 or 15.ran it back up to 40 mph and it stayed at 30#. AT 30 MPH it was like 22 to 25 Its not worth the worry if its gonna blow so after vacation out come the engine for rings rod and mains.going to pull cam and put in new cam bearings.( Im going to make sure the lifters go back on the same lobes.) The engine when it was pulled 6 months ago had no ridge and still had cross hatchs on the bores.Wish I had done it then but at the time it didnt have oil problem.

    Richard richie49
     
  17. robocop

    robocop Member

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    I have a stock pump on 500. It idles around 15psi when warm, 45-50 cold. After it fully warms up the highest oil pressure I see is 35 out on the highway revving around 2500.
    I know that's the stock spec but I don't think its enough as I like to rev it to 5000 plus a little letting it shift at full throttle.
    I think I have a bad rod bearing. I tried adjusting the pressure up but it didn't help any I could see.
     

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