Opinions? Oil pressure acts wierd
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Opinions? Oil pressure acts wierd

  1. #1
    New here Beer:30's Avatar
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    Default Opinions? Oil pressure acts wierd

    So, this is a 350 (+.040) BUICK motor in my 1968 Buick GS California. I had a local builder reman a viable 1972 long-block, as the car had no motor/trans when I bought it. I spec'd the cam, as Comp was doing custom grinds for the same price as off the shelf. It's basically an XtremeEnergy flat-tappet 268H with 112 lc to be a bit more EFI friendly. Stock rockers (new), stock pushrods, etc. It is NOT EFI at the moment, but that has nothing to do with the problem. The rebuild was fairly straight-forward, just a cast-piston street motor. He did work the heads over and was able to fit 2.0" x 1.55" valves along with some light porting and clean up. The engine runs great and is probably one of the strongest street 350 Buicks around. It dyno'd at 352hp (crank), and the most they put out stock was 280.

    The oiling system is essentially stock, other than an upgraded TAPerformance front cover/oilpump assembly. After it was dyno'd, I brought it home, put it in the car, and it was turn-key, ready to drive. Drove it real easy for 150 miles and then started getting into it more. The car went away for body/paint and then upholstery. I got the car back and noticed the oil pressure almost ZERO at idle. I don't honestly know when it started creeping down - or if it did it all of a sudden. Anyway, I contacted the builder and he said there was no oil problems on the dyno - I wasn't there for the dyno run. I was running 10/30 Valvoline with a Fram filter for the first break-in oil that I was running after the dyno oil. He said to put an STP filter on it and run some straight 30 oil and see what it did. I did that and there was no change, other than a TAD higher initial (cold) pressure. It originally had the stock oil pump with a HV kit (spacer plate and longer gears), so I ordered the WHOLE front assembly from TA just to see if that changed anything. It didn't. Same as before.

    Basically, it starts cold with 60 or so oil pressure. Then jumps down to 20-ish. After a few street miles, town driving, the oil obviously warms up and it drops to 3-5psi at idle, 18-22 at cruise (2800-3000). At idle, the lifters DON'T bleed down at all. There is no racket from the motor. It is quiet and smooth. 180 thermostat, alum radiator, electric fans, never gets over 190 (temp that the fans come on). No oil cooler.

    Finally took a vid and want to see if anyone here has any ideas. I've NEVER had a motor do this. It now has 20/50 Valvoline, K&N filter. The pressure has not changed with ANY of the three filters I have tried. The 20/50 has been the best oil pressure yet (no big surprise), but I am just amazed how it starts off great and immediately settles down. Just watch the vid and let me know any ideas you guys have.

    Thanks.

    Quote Originally Posted by gn7 View Post
    EFI is the wave of the future. There can be no denying it. Electronics have been on the leading edge of our entire lives. Not only os the magneto dead, but the standard issue CDI is wavering. Its all about total fuel, air AND spark control. Anybody that thinks its not has their head up their ass.


    2001 SleekCraft 30' Heritage SSB, open-bow mid-cuddy. 496HO / Bravo-I.

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  3. #2
    Senior Member earlbrown's Avatar
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    I've never seen oil pressure look like that with a good front cover. Granted I normally mess with V6's and you've got a couple extra bearings to feed. At the end of the video you blipped the throttle a couple of times and the needle didn't move at all! It should have jumped to damn near full pressure (unless you're bearing clearances are waaaaaaaaay out of whack). It's also a good thing you tossed that HV setup. Those things are horrible on the front cam bearing and dist gear.

    If it were me I'd pull the front cover off and take the pump apart. Read this....

    How to build a front cover/oil pump - TurboBuicks.com

    And see how it compares to what you have. I don't know if TA drills my "booster hole" or not as I'll never have anything from them anywhere near my cars. The other critical areas to look at are the end play on both of the gears.
    Two things might get you using their casting though. TA starts with a chinese casting and "remachines it to tighter tolerances than factory". Personally I don't know how you can machine a hole smaller...
    Those castings out of the box have the pump gears countersunk in the bores. That makes it impossible to set correct end play as the factory covers let the gears protrude a little. If T/A milled that surface down a few thou, you've got something to work with. And if so, hopefully it's still square. Don't buy the T/A oil pump gasket kit. That thing is crap. When I wrote that article, I hadn't put my hands on that kit yet.
    The other thing to watch out for. If you drill out the main oil feed to 1/2" MAKE sure you have access to an alum welder. The chinese covers are bad about blowing out the side as the casting is thin there. If you connect to the adjacent bolt hole, that's not so bad. A copper sealing washer can keep oil off the ground.

    I'm assuming you're not running a oil cooler sammich adapter and are using the large filter for a 455?

    Oh, the felpro number for the gasket kit is TCS45930.... don't trash your front seal as the one in the kit won't work with the chinese cover.
    Last edited by earlbrown; 08-05-2012 at 12:10 PM.

  4. #3
    New here Beer:30's Avatar
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    Quote Originally Posted by earlbrown View Post
    I've never seen oil pressure look like that with a good front cover. Granted I normally mess with V6's and you've got a couple extra bearings to feed. At the end of the video you blipped the throttle a couple of times and the needle didn't move at all! It should have jumped to damn near full pressure (unless you're bearing clearances are waaaaaaaaay out of whack). It's also a good thing you tossed that HV setup. Those things are horrible on the front cam bearing and dist gear.

    If it were me I'd pull the front cover off and take the pump apart. Read this....

    How to build a front cover/oil pump - TurboBuicks.com

    And see how it compares to what you have. I don't know if TA drills my "booster hole" or not as I'll never have anything from them anywhere near my cars. The other critical areas to look at are the end play on both of the gears.
    Two things might get you using their casting though. TA starts with a chinese casting and "remachines it to tighter tolerances than factory". Personally I don't know how you can machine a hole smaller...
    Those castings out of the box have the pump gears countersunk in the bores. That makes it impossible to set correct end play as the factory covers let the gears protrude a little. If T/A milled that surface down a few thou, you've got something to work with. And if so, hopefully it's still square.
    The other thing to watch out for. If you drill out the main oil feed to 1/2" MAKE sure you have access to an alum welder. The chinese covers are bad about blowing out the side as the casting is thin there. If you connect to the adjacent bolt hole, that's not so bad. A copper sealing washer can keep oil off the ground.

    I'm assuming you're not running a oil cooler sammich adapter and are using the large filter for a 455?

    Oh, the felpro number for the gasket kit is TCS45930.... don't trash your front seal as the one in the kit won't work with the chinese cover.
    No, no sammich. Stock spin-on setup as it came from TA.

    I agree on hole sizes and such. However, It HAS to be something that is MOVING, like a flapper or a valve that is getting in the way of an orifice. If there was a problem with end-play on gears or a hole too big or too small - - wouldn't it just have solid LOW pressure from the start and just be CONSTANT? If it fired up low and got lower with heat - It would be easier to accept as "typical Buick low pressure". I have had other Buicks ('87 GN, '87 TurboT) and actually have another '87 GN sitting right next to it that has "average" oil pressure. But, they are all consistent.

    I was thinking spun bearing(s), but how does it correct itself for the next start up and then spin away from the hole again? Plus, I would have a knock or rattle, or at least a squeal.

    The valvetrain rattles a tad (you can hear it at start in the vid), but that's normal. All I did for the video is spin it over a few times to get some fuel to the carb (had sat for 10 days) - then whacked the throttle twice and hit the key. So, that's the choke for handful of seconds then I blip the throttle to show cold idle temp. BTW, the gauges are mechanical - and I checked with an AutoMeter gauge I had laying around....same readings.

    The gauge is off of the front feed, which is the only place I see on the motor for a gauge connection.

    I have driven this car/motor over 1000 miles now. Next time I have it warmed up, I'll snap another video of it warmed up. The idle pressure will make you cringe.
    Last edited by Beer:30; 08-05-2012 at 12:13 PM.
    Quote Originally Posted by gn7 View Post
    EFI is the wave of the future. There can be no denying it. Electronics have been on the leading edge of our entire lives. Not only os the magneto dead, but the standard issue CDI is wavering. Its all about total fuel, air AND spark control. Anybody that thinks its not has their head up their ass.


    2001 SleekCraft 30' Heritage SSB, open-bow mid-cuddy. 496HO / Bravo-I.

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  6. #4
    Junior Member rvrjunky's Avatar
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    Exact same thing happened to the motor i had built for my dually,but took 1200 miles to start losing oil pressure. I tried all the same things you did,finally popped valve cover and found shiny brass pieces, thinking cam bearings. The motor is now out of truck in my garage going back to the builder this week,hopefully nothings really damaged it still ran great just lost oil psi after warm up.


    Quote Originally Posted by Beer:30 View Post
    No, no sammich. Stock spin-on setup as it came from TA.

    I agree on hole sizes and such. However, It HAS to be something that is MOVING, like a flapper or a valve that is getting in the way of an orifice. If there was a problem with end-play on gears or a hole too big or too small - - wouldn't it just have solid LOW pressure from the start and just be CONSTANT? If it fired up low and got lower with heat - It would be easier to accept as "typical Buick low pressure". I have had other Buicks ('87 GN, '87 TurboT) and actually have another '87 GN sitting right next to it that has "average" oil pressure. But, they are all consistent.

    I was thinking spun bearing(s), but how does it correct itself for the next start up and then spin away from the hole again? Plus, I would have a knock or rattle, or at least a squeal.

    The valvetrain rattles a tad (you can hear it at start in the vid), but that's normal. All I did for the video is spin it over a few times to get some fuel to the carb (had sat for 10 days) - then whacked the throttle twice and hit the key. So, that's the choke for handful of seconds then I blip the throttle to show cold idle temp. BTW, the gauges are mechanical - and I checked with an AutoMeter gauge I had laying around....same readings.

    The gauge is off of the front feed, which is the only place I see on the motor for a gauge connection.

    I have driven this car/motor over 1000 miles now. Next time I have it warmed up, I'll snap another video of it warmed up. The idle pressure will make you cringe.

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    Senior Member earlbrown's Avatar
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    The only thing that moves is the relief valve. If it's stuck open then you'll see low oil pressure but it'll still move up and down when you blip the throttle. UNLESS It's stuck so far open you bypass almost all your oil and the cold 20/50 gave you just that little bit extra and everything else got dumped.
    That's stretching it but fairly easy to check. Pop the 1" nut off the oil filter adapter and see if the plunger slides easy and if it's able to bottom out.

    This isn't very scientific but the spring should protrude past the casting about 3/16ish. If it's sticking out an inch, you might have a chip in there holding it open. I hope that's not the case. Buick bearing clearances don't leave any kind of room for trash.

    I'm also wondering if your oil pump pickup is tight against the block. A vacuum leak there usually causes worse symptoms that what you have.

    edit: on another weak idea to check... since this is a new build, have you verified that the dipstick's oil level is correct to keep the pickup submerged?
    Last edited by earlbrown; 08-05-2012 at 01:52 PM.

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    New here Beer:30's Avatar
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    Quote Originally Posted by earlbrown View Post
    The only thing that moves is the relief valve. If it's stuck open then you'll see low oil pressure but it'll still move up and down when you blip the throttle. UNLESS It's stuck so far open you bypass almost all your oil and the cold 20/50 gave you just that little bit extra and everything else got dumped.
    That's stretching it but fairly easy to check. Pop the 1" nut off the oil filter adapter and see if the plunger slides easy and if it's able to bottom out.

    This isn't very scientific but the spring should protrude past the casting about 3/16ish. If it's sticking out an inch, you might have a chip in there holding it open. I hope that's not the case. Buick bearing clearances don't leave any kind of room for trash.

    I'm also wondering if your oil pump pickup is tight against the block. A vacuum leak there usually causes worse symptoms that what you have.

    edit: on another weak idea to check... since this is a new build, have you verified that the dipstick's oil level is correct to keep the pickup submerged?
    I am suspecting the pickup too. It seems as if something is "full" to begin with - and then drops after something empties or gets air introduced. Just wierd.

    No, haven't had any parts off, other than the front cover (replacement). If it was sucking air, I would think there would be surging pressure instead of just solid LOW pressure.
    Last edited by Beer:30; 08-05-2012 at 02:05 PM.
    Quote Originally Posted by gn7 View Post
    EFI is the wave of the future. There can be no denying it. Electronics have been on the leading edge of our entire lives. Not only os the magneto dead, but the standard issue CDI is wavering. Its all about total fuel, air AND spark control. Anybody that thinks its not has their head up their ass.


    2001 SleekCraft 30' Heritage SSB, open-bow mid-cuddy. 496HO / Bravo-I.

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    Senior Member Hass828's Avatar
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    From looking at that Vid, I'd say the pickup had to have fallen off. I wouldnt run it any longer till I had that figured out Paul. It should be relatively easy to find I would think. Make sure the pickup isnt close enough to the bottom of the pan to be sucking down against it and closing off the flow. Let us know what you find, and good luck, Hass.
    "if we keep doing it the same way we always do..we will always get the same results"
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    New here Beer:30's Avatar
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    Quote Originally Posted by Hass828 View Post
    From looking at that Vid, I'd say the pickup had to have fallen off. I wouldnt run it any longer till I had that figured out Paul. It should be relatively easy to find I would think. Make sure the pickup isnt close enough to the bottom of the pan to be sucking down against it and closing off the flow. Let us know what you find, and good luck, Hass.
    Good points. I whole-heartedly believe it to be something with the pickup. Oils and filters have been changed all around with no effect. Oil pump is blueprinted and is different from before - no change. So, either something is on the floor of the pan that gets sucked up against the screen - or - the pickup is moving around.

    I'm pretty sure the crossmember will prevent me from just pulling the pan while the motor mounts are still intact, but looks like pulling the pan is the next thing on the list.

    Thanks guys.
    Quote Originally Posted by gn7 View Post
    EFI is the wave of the future. There can be no denying it. Electronics have been on the leading edge of our entire lives. Not only os the magneto dead, but the standard issue CDI is wavering. Its all about total fuel, air AND spark control. Anybody that thinks its not has their head up their ass.


    2001 SleekCraft 30' Heritage SSB, open-bow mid-cuddy. 496HO / Bravo-I.

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