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Can You Have Too Much Oil Pressure in a Chev 350???

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by Dave1, Jan 17, 2003.

  1. Dave1

    Dave1 Registered Member

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    My 1986 GMC 3/4 4WD pick up with "M" series 350 runs with the 60lb oil pressure gauge pegged most of the time. When at hot idle the pressure will drop to 45 but will swing up and down from 45 to the peg in sharp spikes of pressure readings. As soon as you accelerate the oil pressure immediately pegs the 60lb guage.

    I run Castrol 10w30 or 30w. The engine was rebuilt before I bought it and it was mentioned that a high volumne oil pump had been installed when rebuilt. My questions are; what would cause the up/down swings in the pressure reading at idle and also is the extremely high oil pressure while running OK? Thanks, Dave
     
  2. BLZN4FN

    BLZN4FN 1/2 ton status

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    Hey Dave,
    First thing I would do is hook up a mechanical psi gauge
    to the motor to see what the motor is realy doing. Your oil
    psi maybe ok but you may have a bad gauge or a bad oil psi regulator.
    Hope this helps.
    Bo
    /forums/images/graemlins/thumb.gif
     
  3. zakk

    zakk 1/2 ton status

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    you could blow out the seals. i would do as the other post says to see if it really is at 60 psi.

    a rule of thumb is yu want 10lbs of pressure for each 1,000 rpm. i am a little below that, but it is just a gauge.
     
  4. WhiteWhomper

    WhiteWhomper 1/2 ton status

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    I'm running a Melling Hi-Pressure/Hi-Volume oil pump and when cold, my oil pressure can reach around 80 psi and normally runs about 55 - 65 psi even when warmed up. After a full day of trail running, the pressure will drop quite a bit even down to the 30 psi range, but I like having the extra pressure and volume since my motor is about worn out and I think the extra oil is all that stands in the way of a melt down. But for a motor in good condition, the 10 psi for every 1000 rpm has always been a good rule of thumb.
     
  5. rodzzilla

    rodzzilla 1/2 ton status

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    A friend of mine had a stock car a few years ago. He did the old stretch the pressure spring trick. First time he fired it up, he ran it up on the lift. Looked at the oil filter starting to swell /forums/images/graemlins/eek.gif /forums/images/graemlins/eek.gif. Luckily for him he was able to drop it down and shut it off before the filter burst. I think that was the last time he stretched a spring.
     
  6. rogerwilco71

    rogerwilco71 1/2 ton status

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    </font><blockquote><font class="small">In reply to:</font><hr />
    runs with the 60lb oil pressure gauge pegged most of the time

    [/ QUOTE ]
    Oh ya, I have so much oil pressure that I have limiting-straps on my valvecovers.
    I'd recommend the mechanical gauge too, and might as well throw the water temp gauge while you're at it...heck, it's probably cheaper to get the trio cluster that includes voltage. You'll find out more about how your engine is running that way because the Gremlins never talk.
    ....AND WELCOME TO COLORADO K5!
     
  7. Lonnie

    Lonnie 1/2 ton status

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    If the gauge is jerky, I would doubt the gauge or sender is operating properly. If the mechanical gauge confirms it is correct, I would recommend finding the 80# gauge &amp; sender from a 6.2 diesel pickup so at least you get a reading, not just somewhere above 60 pegged.

    You will not blow any seals other than the possibility of the oil filter gasket. This usually does not happen until above 100-120psi.

    You will have to worry about accelerated distributor/cam gear wear with high pressure (above 70 constant I would be concerned). The required pressure is 10# per 1000 rpm for a small block with a minimum of approx. 20# at idle.

    Chances are if it is above 60# (hot) then you have a high pressure pump or stuck relief valve in the pump. Your gauge reading will tell this, it will quickly reach a limit &amp; then quit rising. If it continues with RPM, the relief is likely stuck.

    If only 60#, do not worry, my high volume Melling pump holds 60 at anything above 1500 rpm &amp; has done this for years with no problems. Easy on the rpm when the engine is cold as pressure is really high then. You can also use thinner oil to lower pressure if it is excessive. Save the 20w50 for race cars, use 10w40 or even synthetic 5w50. You may even increase mileage a little.
     
  8. Dave1

    Dave1 Registered Member

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    Re: Why Didn\"t I Think of That???

    Thanks for the warm welcome. Actually I have been visiting this site and reading for some time. Have learned alot from you guys.

    A new guage pak it is. Will try to have one in place by the end of the weekend. My main concern is the up down swings of oil presure at idle. It will swing sharply up and down from 40-peg-40 which on the stock dash 60lb guage is about 1/3 of the guage face. It is bugging me cause you can't help but look at it and worry when it is jumping up and down like that. Almost seems like it is sucking air or the pick up is leaking or something..??? As soon as you touch the gas and add any RPM it immediately pegs the gauge and it stays pegged until you idle down again.

    Thanks for all of the replies. I'll add the mechanical guage and see what it looks like then.

    Dave1
    Winter Springs, Florida
    (Near Bikini Land)
     

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