Brand new engine, start first time, oil pressure pegs out.

Discussion in 'GM Powertrain' started by Big6ft6, Nov 4, 2008.

  1. Big6ft6

    Big6ft6 Rockstar 100 Posts

    I have a freshly rebuilt TBI 350.

    I'm doing the delicate dance of the getting it started and breaking in the cam etc. I went to start cam break in today and noticed that when I start the engine, the pressure gauge instanly pegs out past 60psi.

    I completely freaked out and shut the engine down (another check mark against proper cam break in). I have checked and oil is pumping up out of the pushrods into the lifter valley.

    Now I don't know what to do. What should the pressure be at? What should be my biggest concern?

    I am using Royal Pruple Break in oil with high zinc etc.

    What really worries me is that I've heard a couple of short squeals a couple of time when starting and shutting of the engine. It is really freaking me out.

    I feel like I'm stuck becuase I'm not even supposed to be turning the engine over until everytyhing is set to break in the it limits my diagnostic ability.

    What should I be 60psi this normal becuase it is a "tight" engine and newly rebuilt.

    Sorry this is a rambling post, but I'm very very worried.
    Last edited: Nov 4, 2008
  2. dwill3015

    dwill3015 Epic Member 5+ Years ROTM Winner 1000 Posts

    60PSI seems normal as the 350TBI new GM crate motor in my Blazer runs at 60PSI
  3. APX

    APX Member

    It could be the Gauge going, too. Mine did that before it went out.

    GM has an internal Service Bulletin that if a customer comes in and complains about the gauge cluster being out, a new one is supplied (parts + labor free). I do not believe that there's a mileage cap either.
  4. JMoney02

    JMoney02 Epic Member 5+ Years 500 Posts

    No worries mate, money is a bad thing to waste and any help can be some relief...... Let us know....
  5. Big6ft6

    Big6ft6 Rockstar 100 Posts

    Thanks Dwill

    I'm not sure mine oil pressure is 60psi...that is simply where my gauge ends, the needle pegs the end of the gauge, so it could be 160psi as far as I know. I'm getting the feeling that high oil pressure is never really a bad thing from everyone's responses.

    Is that a general consensus?
  6. Big6ft6

    Big6ft6 Rockstar 100 Posts

    JMoney, thanks for your reassurance. I have the cam sheet from the engine builder, it appears it may have been some cheap no-name cam. I wasn't the person who had the engine rebuilt, I bought it from the guy who had it rebuilt, so I don't know for sure about the cam brand.

    It is supposedly the cam that would provide the most torque in a TBI motor without having to adjust the computer at all, so it definitly is not a radical cam.

    It is a flat tappet hydraulic lifter cam, I know that much. Everyone seems to say for flat tappet cams you have to run the engine unloaded at 1800rpm for 20 minutes immediately upon start up to break in cam. If you let it idle at all, you've screwed up I've been told.

    But I've had to crank this motor so much (becuase of a different problem) I'm afraid I already ruined
    the pre-lube on the cam so I can pretty much kiss proper cam break-in "good bye". Now I just don't want to have the engine ruined as well.
  7. DirtDog

    DirtDog Rockstar 100 Posts

    you should be ok. I rebuilt a 350 a few years back and it held about 70psi oil pressure. Just fire it up and go through the break in procedure. It's normal to hear some small noises at first, but they will go away after it runs for about 30-45 mins. My 2007 Silverado has a 4.3L V6 and it holds steady at about 55psi oil pressure and it hits almost 70 when first started up. here is a picture of my gauges after the truck has been running about 5 minutes.


    Hope this helps
  8. Big6ft6

    Big6ft6 Rockstar 100 Posts

    Jack, I appreciate it, that is exactly the type of reassurance I need. I think at this point, I just need to go for it. I can sit and fret about what damage I've done already, what the different noises are, if it is now too cold outside to start and engine for the first time, but in the end, I just have to to do it.
  9. DirtDog

    DirtDog Rockstar 100 Posts

    You're most welcome. It can be a scary thing to start up a fresh engine for the first time. I was the service manager at the local Chevy dealership here in Livingston for 3 months, and I got to do the PDI (pre delivery inspection) on all the new cars and trucks that came to the dealership. almost all of them would make some little noises when first started up, but they would go away after a few minutes. It's just simple thinking, you have a new engine full of new un worn parts, they will make some racket until they get "worn-in" and everything becomes seated properly. This is why the break in period is so important. I'm glad I could help you.

  10. JMoney02

    JMoney02 Epic Member 5+ Years 500 Posts


    Now food for thought. Only run the break in oil for 500 miles. Change to a good grade oil for you 3mo/3k timeframe and then do it again for 3mo/3k miles. After this you can run any synthentic blend
    if you wish, but should break in with regular oil first. Just did the S15 Jimmy that I have 2 yrs ago with a 4.3l Vortec, Roller Motor and have 6k on it now and its running great, with Catrol Full Syn 10w/30.
    The Jimmy is a toy to tinker with and even now with how many motors that I've built it still is nerv
    racking at first start up, even with all the checks and rechecks, but when it fires, BAM....:biggrin: Ain't
    Nottin' better....... Glad I/We all could help......

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