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Oil pressure question, high volume, high press or OEM

Discussion in 'The Garage' started by JHG, Feb 2, 2004.

  1. JHG

    JHG 1/2 ton status

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    The oil pressure on my 350 sbc is around 12-15 at idle in Drive (almost 20 in neutral or Park), when the engine is hot (higher if its cold). It is around 35-40 at higway speed.

    I have a mechanical oil pressure gauge from Autometer and I know it is correct.

    I have heard its ok to have such a low pressure, but it is a sign of the motor is getting old.

    I was wondering if it would help to put in a high volume or high pressure oil pump, and wich would be better.

    I cant put the truck in my garage (car garage, not a truck garage) so I will have to work on it outside and its rather cold at the moment /forums/images/graemlins/crazy.gif Thats the reason I am looking for an easy fix.

    To sum it up, should I buy a high volume oil pump, a high pressure oil pump or just do nothing /forums/images/graemlins/whistling.gif

    Jon H. Gudjonsson,
    1981 Blazer K5, 350/TH350, NP208, D44/12 bolt, 4.88, lockers, 38"/44" tires.
     
  2. rjfguitar

    rjfguitar 3/4 ton status GMOTM Winner

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    How many miles on the motor? Totally stock? I would wait until it warms up a little and get a high volume melling pump if it bothers you that much. I would say your current oil pressure isn't all that bad for a stock motor with (i'm guessing) some miles on it. You are right at the rule of 10 psi for every 1,000RPM's, thats what you should have if the motor is ran hard.
     
  3. GMCLegacy

    GMCLegacy 1/2 ton status

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    a 350 will run a long time under the conditions you mentioned. my truck ran with far less oil pressure for 3 years, with a 2000 mile drive round trip running 15-20 psi at 3000rpm with thick 20w50, and a ton of idle hours in the woods with the needle of my autometer mech gage resting at 0-5. it finally started to knock and i rebuilt another engine.

    a lot of people throw thicker oil in it. i did that in the summer but it is not a fix. yeah you have more pressure on your gage, but i dont think it would be good on the engine on cold startups.

    looking back i wish i would have put a high volume pump (or similar) in it when i first got the truck, to see if it really would have prolonged the life of the engine.

    more oil pressure is not going to fix a worn out bearing. and please dont put lucas oil or any other "seen on TV" $hit in your engine.
     
  4. Goober

    Goober 1/2 ton status

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    [ QUOTE ]
    12-15 at idle in Drive (almost 20 in neutral or Park), when the engine is hot (higher if its cold). It is around 35-40 at higway speed.



    [/ QUOTE ]


    If it were mine, I would just leave it alone. I think that should be sufficient oil pressure for a mild small-block.

    You could try some 10w40 next time you change your oil if you really want to bring up the idle pressure. That might give you a few PSI.

    If I were to go through the trouble of replacing an oil pump because of low pressure then I would also be checking rod and main bearings while I was in there. And since I would be tearing the bottom end up then I might just consider pulling the engine and doing rings while I'm at it.


    /forums/images/graemlins/grin.gif /forums/images/graemlins/grin.gif /forums/images/graemlins/grin.gif /forums/images/graemlins/grin.gif /forums/images/graemlins/grin.gif
     
  5. rjfguitar

    rjfguitar 3/4 ton status GMOTM Winner

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    [ QUOTE ]


    If I were to go through the trouble of replacing an oil pump because of low pressure then I would also be checking rod and main bearings while I was in there. And since I would be tearing the bottom end up then I might just consider pulling the engine and doing rings while I'm at it.


    /forums/images/graemlins/grin.gif /forums/images/graemlins/grin.gif /forums/images/graemlins/grin.gif /forums/images/graemlins/grin.gif /forums/images/graemlins/grin.gif

    [/ QUOTE ] Exactly... /forums/images/graemlins/thumb.gif
     
  6. bablazer73

    bablazer73 1/2 ton status

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    [ QUOTE ]
    Quote:
    --------------------------------------------------------------------------------



    If I were to go through the trouble of replacing an oil pump because of low pressure then I would also be checking rod and main bearings while I was in there. And since I would be tearing the bottom end up then I might just consider pulling the engine and doing rings while I'm at it.
    /forums/images/graemlins/grin.gif /forums/images/graemlins/grin.gif /forums/images/graemlins/grin.gif /forums/images/graemlins/grin.gif /forums/images/graemlins/grin.gif




    --------------------------------------------------------------------------------

    Exactly... /forums/images/graemlins/thumb.gif

    [/ QUOTE ]
    Ands thats where I'm at also. At this point, The oil pressure you have is enough. If you do go ahead and put ANY oil pump in there, it's just a band-aid fix. At some point, it will get worse and will have to come out anyways.

    For future knowledge, I would NOT use a High volume pump in a stock engine. High volume pumps can move up to 40% More oil, But if you don't have a oil pan that carries more oil, You run the risk of running pan dry at higher RPM's. And trust me, thats bad!! A simple high pressure pump is enough fro most mild street engines.

    You can rering and put bearings in WITHOUT pulling engine, just pulling heads, drop the pan and have at it!
     
  7. JHG

    JHG 1/2 ton status

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    Thank you all for your input. The motor has a lot of miles on it but its running very strong.

    Perhaps I should do nothing with this motor and start rebuilding a new one (or start looking for 6,5 TD /forums/images/graemlins/pimp1.gif ).

    I know if I start tearing it apart I will not know when to stop. I will tear it in pices and rebuild everything.

    I cant do that right know because my truck /forums/images/graemlins/k5.gif is my only running vehicle at this time (my TA was rearendet last fall, and will be ready in april or may).

    Thanks, Jon H.
     
  8. rjfguitar

    rjfguitar 3/4 ton status GMOTM Winner

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    [ QUOTE ]


    Perhaps I should do nothing with this motor and start rebuilding a new one (or start looking for 6,5 TD /forums/images/graemlins/pimp1.gif ).



    [/ QUOTE ]That is what a LOT of people do. Build the motor the you wan't while your truck still runs, build as you have the money, and drop it in when it's completed. Thats exactly what I did...I had a 350 with about 80,000 on it and I was very unhappy with it's power output so I started my 406 and when the motor was completed I dropped it in and sold the old 350 for $150. /forums/images/graemlins/woot.gif
     
  9. Z3PR

    Z3PR Banned

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    I think you'd be better off starting with a rebuildable engine and build it the way you want. I've ran the Melling high pressure/high volume oil pumps in the hot rod motors /forums/images/graemlins/waytogo.gif I like them, I like them alot, but don't know /forums/images/graemlins/dunno.gif if a stock motor would really need one or if a stocker would be better. /forums/images/graemlins/thinking.gif
     

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