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  1. #1
    Join Date
    Jul 2016
    Posts
    5

    Default 455 no oil pressure

    Guys a Bought a 1970 GS Stage 1 some months ago, just when I got the engine running I checked for oil pressure and I had like 30 PSI at idle @900RPM and 1500 RPM and above I had like steady 65 PSI. This weekend started the car after three months sitting, the oil pressure was about the same but just after dealing a bit with the carb I noticed that now the oil pressure is zero! sometimes the gauge shows something like 5 PSI and next it will drop to zero, I though was a gauge problem so unplugged it with engine running expecting to see oil coming out from the hose but I got nothing! no oil coming at all

    I don't know what happened, now if I rev the engine more than 1500 RPM it starts shaking like if it were misfiring and the vacuum gauge needle starts shaking a lot! (at idle doesn't shakes but I can't get more than 13" of vacuum)

    The engine has never been rebuilt and has like 90000 miles on it, I don't know which oil viscosity is the current oil the engine has but I was planning to change it for 10W30

  2. #2
    Join Date
    Feb 2002
    Location
    Garfield Hts, Ohio
    Posts
    4,856

    Default Re: 455 no oil pressure

    First off, stop running the engine if its showing "0" pressure.
    Remove the oil filter, look at the oil bypass valve, the older versions (such as yours) had a flat disc as the valve, I've had that valve get cocked sideways. See if yours is.
    The newer (late 70's oil filter adapter) use a self centering valve.
    Let us know what yah find
    Oh take pics too!
    71 GS 350 (mine) Best so far 13.65 @ 98.84 mph
    SP3 track testing to resume in 2016!
    413 cam going away, switching to TA roller, starting again with Stage 1 and Q-Jet, then to SP3 and AED
    87 Grand National (Hers) no passes yet
    00 Monte Carlo
    2001 GMC Safari AWD
    2007 Mazda 3
    Ranch house with 4 dogs and a cat

  3. #3
    Join Date
    Feb 2002
    Location
    Oakland Gardens, N.Y.
    Posts
    27,442

    Default Re: 455 no oil pressure

    First, like Mark said, don't run the engine with no oil pressure. You can do a lot of damage to the engine. You took a big chance unplugging the oil sender with the engine running. Normally, that would create quite a mess.

    Being the engine is not running correctly either, I would suspect a problem with the distributor gear, or a problem with the timing chain. The cam drives the oil pump along with the distributor. Remove the distributor cap, and have someone crank the engine while you watch the rotor. See if it turns smoothly, or herky-jerky. If you can, turn the crank with a breaker bar and see how much slack there is in the timing chain. Turn the crank one way, then the other while watching the rotor. Remove the distributor after marking it's position, and inspect the distributor gear. Look for gear damage. With the distributor removed, you can drive the oil pump with a drill to check for oil pressure. Not to overlook the obvious, have you checked the oil level?
    Last edited by LARRY70GS; 01-10-2017 at 09:42 AM.
    Larry
    1998 "Fully Optioned" SC3800 Riviera
    70 GS 455 Stage1, TSP 470, 602 HP@ 5900, 589 TQ @ 4900
    TA Hyd Roller Cam, 230*/238*, 112, .544"/.577" lift, 4-7 swap
    MSD Digital 6+, Ignitionman Distributor w/MSD trigger
    THM400 with Ultimate 258mm converter, Gear Vendors OD
    AED 1000 HO Carb, 800 CFM 7042240 Quadrajet
    8.5 10 bolt, 3.73's Race weight 4025lbs.
    Best E.T. 11.54 Best MPH, 116.06
    Larrymta@verizon.net, GSCA #291
    BPG # 1063
    N.E. GS/GN Club Assistant Director

  4. #4
    Join Date
    Feb 2002
    Location
    tidewater VA
    Posts
    188

    Default Re: 455 no oil pressure

    I would pull out the oil pump pressure relief valve, very easy to do, make sure is it free moving, probably stuck open not letting oil pressure build.

    Motor is probably running rough due to lifters not pumping up due to no oil pressure.

    Please don't run the motor without oil pressure, it will cause major damage.

    Good luck
    67' GS400 >462"/400/3.55's
    12.51@106.5mph

  5. #5
    Join Date
    Jul 2016
    Posts
    5

    Default Re: 455 no oil pressure

    Some updates here :D

    Yesterday removed the Oil filter and it was completely dry so filled it with a half quarter of 10W30 oil, reinstalled it and after cranking the engine for 5 seconds I saw oil coming out from the oil pressure gauge line so took the chance to start the engine, after 3 seconds idling the oil pressure gauge started showing some oil pressure, about 20 PSI at idle, after rev the engine a bit the pressure increased up to 60 PSI and then continue idling at 35 - 40 PSI for 20 minutes with any change or drop in oil pressure but the engine hesitations doesn't stop, I'm starting to think is related to the new ignition wires I installed just before this problem appeared

    I don't know what could happened but I'm happy to see it working again

    Quote Originally Posted by redbuick View Post
    I would pull out the oil pump pressure relief valve, very easy to do, make sure is it free moving, probably stuck open not letting oil pressure build.

    Motor is probably running rough due to lifters not pumping up due to no oil pressure.

    Please don't run the motor without oil pressure, it will cause major damage.

    Good luck
    Where's that valve or how can I check it?

  6. #6
    Join Date
    Apr 2012
    Location
    Magnolia, Delaware
    Posts
    759

    Default Re: 455 no oil pressure

    The front of the oil pump near the filter has a big nut. I think 1 inch? The pressure relief valve is under there with a spring. Did you check the bypass? valve (not sure if it is correct nomenclature) inside where the filter goes?
    John Schaefer

    "I haven't heard so many lies 'less I was tellin' them"!

    - Rowdy Roddy Piper

  7. #7
    Join Date
    Feb 2002
    Location
    Oakland Gardens, N.Y.
    Posts
    27,442

    Default Re: 455 no oil pressure

    If you just installed ignition wires, double check the firing order, you wouldn't be the first guy to have it wrong, happens to the best of us. Also, oil pressure will be the highest when the engine is started cold. It will be the lowest after the car is driven at highway speeds for 20 minutes or so. That is what it takes to get the oil the hottest it will get.
    Larry
    1998 "Fully Optioned" SC3800 Riviera
    70 GS 455 Stage1, TSP 470, 602 HP@ 5900, 589 TQ @ 4900
    TA Hyd Roller Cam, 230*/238*, 112, .544"/.577" lift, 4-7 swap
    MSD Digital 6+, Ignitionman Distributor w/MSD trigger
    THM400 with Ultimate 258mm converter, Gear Vendors OD
    AED 1000 HO Carb, 800 CFM 7042240 Quadrajet
    8.5 10 bolt, 3.73's Race weight 4025lbs.
    Best E.T. 11.54 Best MPH, 116.06
    Larrymta@verizon.net, GSCA #291
    BPG # 1063
    N.E. GS/GN Club Assistant Director

  8. #8
    Join Date
    Feb 2002
    Location
    tidewater VA
    Posts
    188

    Default Re: 455 no oil pressure

    Quote Originally Posted by josehf34 View Post
    Some updates here :D

    Yesterday removed the Oil filter and it was completely dry so filled it with a half quarter of 10W30 oil, reinstalled it and after cranking the engine for 5 seconds I saw oil coming out from the oil pressure gauge line so took the chance to start the engine, after 3 seconds idling the oil pressure gauge started showing some oil pressure, about 20 PSI at idle, after rev the engine a bit the pressure increased up to 60 PSI and then continue idling at 35 - 40 PSI for 20 minutes with any change or drop in oil pressure but the engine hesitations doesn't stop, I'm starting to think is related to the new ignition wires I installed just before this problem appeared

    I don't know what could happened but I'm happy to see it working again



    Where's that valve or how can I check it?
    It sounds like the oil pressure relief valve is OK, if your building oil pressure it's not stuck. BTW It's down by the filter, big nut facing forward with spring and relief valve, no surprises if you remove it, my have to fish out the valve with a scribe.
    67' GS400 >462"/400/3.55's
    12.51@106.5mph

  9. #9
    Join Date
    May 2002
    Location
    the Seasonally Frozen Wastelands
    Posts
    2,850

    Default Re: 455 no oil pressure

    Quote Originally Posted by Mark Demko View Post
    First off, stop running the engine if its showing "0" pressure.
    Wise.

    Quote Originally Posted by Mark Demko View Post
    Remove the oil filter, look at the oil bypass valve, the older versions (such as yours) had a flat disc as the valve, I've had that valve get cocked sideways. See if yours is.
    The newer (late 70's oil filter adapter) use a self centering valve.
    Let us know what yah find
    Oh take pics too!
    You could take the disc OUT and it wouldn't change oil pressure. It would allow unfiltered oil into the oil galleries, however.

 

 

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