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Oil Pressure running low

Discussion in 'The Garage' started by Bross82, Oct 16, 2006.

  1. Bross82

    Bross82 1/2 ton status

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    The oil pressure is reading out at 35-40 psi when the engine is cold. After it gets hot, the pressure reads out at about 30 psi with load on the engine. It drops down to about 20 psi being in drive and at a complete stop. It went as far down as 14 or so psi yesterday when it was in 4 low at a stop. Shouldn't the pressure stay pretty consistent and not change with the rpms of the motor?

    I do know that a few cylinders have a valve leak, with oil built up on the spark plug when i change them. But, its not where it creates any visible spoke out the tailpipe. Also, I'm getting this reading on a new mechanical autometer oil pressure gauge.

    Could this be the oil pump or possibly the screen needing to be changed or does it seem more like something else?

    Thanks!
    matt
     
  2. badmix

    badmix 1/2 ton status

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    Tag for others but,

    Ive never seen an oil pressure gauge STAY the same thru and RPM range, the faster you go the fast things move and more pressure its slinging. But im curious about the readings to see what others say.
     
  3. obijuan

    obijuan 1/2 ton status GMOTM Winner

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    a oil pressure gauge should change with the rpms but are you sure theres no air in you new lines? give it a while and let it break in i guess...? i dont know if that would do anything but hell lets see what others say
     
  4. diesel4me

    diesel4me 1 ton status Premium Member

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    dont worry--be happy...

    My SB400 I had in one truck had great COLD oil pressure--35-50 psi--it then dropped to 30 psi at speed,and at idle in drive it often dropped to as low as 7 psi..the motor had well over 100,000 miles,and had never been opened up..
    I drove it pretty hard too..

    I just decided to ignore it--it never ticked or knocked,and I had it since 1990--I sold it a few months ago,still doing the same thing...it did have lots of end play though,but I doubt that had any affect on oil pressure..Iwouldn't worry about yours if it maintains 10 psi at idle..its probably bearing clearences on the "loose" side or a worn oil pump causing it..if you hear a woodpecker sound upon a cold start for a few seconds,the bearings are probably on the loose side..if its quiet,it will probably go like this a long time...:crazy:
     
  5. cjjones

    cjjones 1/2 ton status

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    I have a rebuilt 400, good oil pressure then one day I noticed my oil pressure was very sparatic, real low at idle and not too high at 60mph. Weird thing was I unhooked my heater fan a few days earlier, not noticing anything then. I hooked it up the other day and bang, oil pressure is great again, weird I know but cannot answer what is going on.
     
  6. gmc4cw

    gmc4cw 1/2 ton status GMOTM Winner

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    the older SBC don't have much pressure. I had a new 350 built, not rebuilt. 25-40 psi depending on RPM. mine idles at about 10 psi. you shouldn't have anything to worry about unless you are hearing noises that are not normal.
     

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