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Oil Pressure FAILING!!!

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by Bross82, Feb 21, 2003.

  1. Bross82

    Bross82 1/2 ton status

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    It started yesterday when they oil pressure was running at 30 instead of closer to 45... so i checked and added oil hoping it would be fine. i have an oil leak, and it would either run high when it needed oil or run low if i needed oil. Today, it was running at 15 and then it even went to 0. it would especially go to 0 and stay there in reverse and after running a while would go close to there no matter what. but would raise up to about 15 while pushing on the gas. later when i started my truck to go home it was at 30, but by the time i was near home it was at 15 and i backed in so i could maybe look at it tomorrow. as soon as i put it in reverse it went to 0 and stayed there until i turned it off.

    any help would be greatly appreciated,
    matt

    not expecting positive feedback since a friend and i found the inside of a lifter in his oil pan after he experienced similar issues and he's currently in the process of replacing his cam, lifters, push rods, etc.
     
  2. the professor

    the professor 1/2 ton status

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    Any engine noises....lifters tapping..??
    --
    Not to be a smart a**, but you do realize the engine NEEDS oil to lube its internals
    --
    If you have been running the engine lo on oil, due to an oil leak..

    every time the oil pressure drops..it is usualy because the oil gets extemely hot..and is starting to break down..

    Every time it goes to zero, you bearings are getting no oil...plain bearings and flat tappet cams, as opposed to ball or roller bearings and roller cams..REQUIRE oil plressure to maintain hydrodynamic lubrication

    The bottom line here, is there is a very good chance you have spun (destroyed) a rod, main or cam bearing..and the oil pressure is being dumped internaly

    An immediate check with a "test" oil pressure gage, to eliminate a gage problem is in order..

    If you in fact have no oil pressure, or extremely running pressure, and near zero at idle....

    You can fingure you have about 10-100 miles until the engine destroys itself /forums/images/graemlins/crazy.gif

    Good luck /forums/images/graemlins/cool.gif /forums/images/graemlins/truck.gif
     
  3. Can Can

    Can Can Pusher Man Staff Member Super Moderator

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    I agree with the professor- pull out your oil pressure sending unit and install a mechanical gauge right on the block. This will give you a true reading and rule out a broken sending unit or inaccurate dash gauge......
     
  4. Bross82

    Bross82 1/2 ton status

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    yeah i know it needs oil.

    as far as the noises its hard to tell, my exhaust donut on the driver side has a pretty good leak, it seemed to sound the same as far as with that leak when i just came home. but in the afternoon when it was idling the passenger side exhaust didnt sound right it was popping more and louder with a slightly hollow sound to it (exhaust is normal louder than normal with dual exhaust with flowmaster mufflers rectangular in shape, not oval).

    this reminds me that a number 6 cylinder valve seal was going and leaked oil all over the spark plug. could this have completely gone and be causing the pressure problems????


    thanks,
    matt
     
  5. Bross82

    Bross82 1/2 ton status

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    also, is there any chance that it could be the oil pump? or do those usually just go. pretty much, if its not the gauge its probably not looking good for the engine right?

    matt
     
  6. Can Can

    Can Can Pusher Man Staff Member Super Moderator

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    If your oil pump is dying you'll probably notice an increase in operating temperature. The lack of oil circulation causes the motor to run warm...
     
  7. Bross82

    Bross82 1/2 ton status

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    when it was making that popping noise it was reading out between 0 and 15 and the temp did probably raise 10-15 degrees...but on the way home when it was running oil pressure 15-30, it was mostly normal temp i think, maybe 5 degrees or so hotter.

    matt

    hey, it was about a week or two before another part went. so, hey why not right? usually was a different part once a month though, and not something so major.
     
  8. twenty_below0

    twenty_below0 1/2 ton status

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    The professor , though new to the forum is VERY knowledgeable as is Canmore so do what they suggest first . I have had a pump pickup slip out of the pump about a 1/4" and cause the oil pressure to fluxuate slowly dropping and by the time I noticed it I had driven it approximately 20 miles and it was rattling pretty good on the top end . We all have loud exhaust's or most of us and you can hear the top end rattling even with REALLY loud exhaust if your oil pressure is infact that low . So if it's not rattling with 0 pressure at an idle and with giving it some more gas it dont really rattle maybe you lucked out . good luck /forums/images/graemlins/thumb.gif
    >>>>>> Oh , because of the problem >>>>>>
    I did hose the engine, I put a new cam,lifters, pump etc. and it ran ok but the oil pressure was never the same , the oil pan had a substantial layer of babit on the bottom , which is bearing material , so I babied it for a few months and built the motor I have now . GOOD EXCUSE /forums/images/graemlins/wink.gif
     
  9. cheyenne_77

    cheyenne_77 Registered Member

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    i Agree with the above, low oil pressure:
    bearings ratshit,
    Oil losing viscosity,
    oil pump.
    Change your oil first,
    check your oil pressure with an external guage then if still not good check your pump and then your bearings. /forums/images/graemlins/smirk.gif
     
  10. schmuck

    schmuck 1/2 ton status

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    this happened to me once i had a motor i just rebulit get no oil pressure at idle and would never go over 10psi with the pedal down so i checked it with other gauges other oil pumps and i built it so i know the bearing clearences were good it turned out to be the fitting that the mechanical oil pressure gauge tube connected to on the block was cracked and i could not get it out
     
  11. tecton

    tecton 1/2 ton status

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    my oil pressure is mabye 10 at idle and 20 on the gas...but it's constant...not getting lower or anything... similar problem?

    only 2800 miles on motor, too young to die
     
  12. 4DiggerDan

    4DiggerDan 1/2 ton status

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    A valve stem seal busted would NOT cause a loss in oil pressure. All they do is keep excessive amounts of oil from getting into the cylinder. Even then, you really only need them on the intake valves. When the engine is running, the exhausts want to blow the oil back up in the valve cover. Lots of Chevy's only had the little cheez dik "O" rings under the valve locks and didn't even have umbrellas. Then again, you sais that you slipped in a new cam. Umbrellas are only good for about .450" worth of lift (if you're easy on them and not winding the motor up on a regular basis.) Much more lift than that, and you SHOULD have the guide bosses machined for a REAL positive stem seal. AKA, NOT the factory .540" ID ones that came stock on engines from the mid 80's up.

    If you actually DO have an oil pressure problem, another thing to check is the rod on the bottom of the distributor. Its a hex shape (like an allen wrench,) its what drives the oil pump. Usually this isn't a problem on a stock engine. But if your mill sees RPMs up around 5-5500 + on a regular basis, they can start to round off. Why they won't just quit running the oil pump I'll never know. Sometimes they'll do exactly what your describing when they're on their way out.

    When you change your oil, look for chunks of bearing. In fact, I'd cut apart that filter and look in there too... If you pull the mill out and tear it down... If you see copper color showing through the bearings (mains, rods AND cam,) you've found your trouble...
     
  13. cheyenne_77

    cheyenne_77 Registered Member

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    Hex driver on the pump? I have the 400 ci and it is slotted on either side like a large screwdriver. i run a ford windsor in my race car and it runs a hex key like set up. (i replace it with a milodon unit, thicker shank) /forums/images/graemlins/cool.gif
     

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