No oil pressure
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From: New Jersey
No oil pressure Just put in a new GM oil pump. Started it and had about 50 psi. After I let it idle for a few minutes the pressure started to drop then went to 0. Shut it off and started it again and the same thing. Now it fluctuates between 10 and 40 then drops to 0. It's not the sending unit because it starts to get a lifter tap and rocker chatter. Any ideas of what the problem might be?
Thread Starter
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From: New Jersey
**** man, I dont want to pull it apart again. That would cause it to go from high to no pressure? Any chance of a clogged filter?
Does the o-ring go above the "lip" on the pick up tube?
Does the o-ring go above the "lip" on the pick up tube?
It goes here, not above the lip. I put lucas oil on mine so it slid right into the pump.
Could be a stuck pressure relief also. I would remove the pump and check it. Mine stuck open, thus my rebuilt engine now.
Could be a stuck pressure relief also. I would remove the pump and check it. Mine stuck open, thus my rebuilt engine now.
Thread Starter
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From: New Jersey
Thanks for the pic. Yea that's how I put mine on. Just as a side note, the previous owner said it needed an oil pump because it dropped pressure. So while I was taking off the under drive, I noticed there was a point indent from a pulley puller on the crank bolt. When i got to the pump it looked fairly new, no sludge build up or anything. Could we have both messed up the o-ring or it's something else? And there's no way this would be a clogged filter? Im just confused of how it starts with pressure, then drops, then comes back some, then drops.
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Is this a new pump? Melling, ls6? Maybe you both messed up the oring. I would take it apart again and do it slowly when you take off the pickup tube, see if it is pinched under there.
There are 2 things that make the oil pressure, oil flow and the bearing clearances, if you have large bearing clearances, you wont have alot of oil pressure. it really sounds like a pump o ring problem. I would put a new pump in it, thats what I did, 1000 miles later, lots of metal in the filter, I cut it apart.
It could be the oil pressure relief stuck open, but when my car did this, it had 0 oil pressure on start up. I took my pump apart and carefully inspected it. I noticed the passage way open for pressure relief. I eventually figured out how it worked and pushed on the relief, it was stuck in the open position.
On a side note, your motor will only live a short while on low oil pressure. My car did not run long, I had to rebuild it after my mishap.
There are 2 things that make the oil pressure, oil flow and the bearing clearances, if you have large bearing clearances, you wont have alot of oil pressure. it really sounds like a pump o ring problem. I would put a new pump in it, thats what I did, 1000 miles later, lots of metal in the filter, I cut it apart.
It could be the oil pressure relief stuck open, but when my car did this, it had 0 oil pressure on start up. I took my pump apart and carefully inspected it. I noticed the passage way open for pressure relief. I eventually figured out how it worked and pushed on the relief, it was stuck in the open position.
On a side note, your motor will only live a short while on low oil pressure. My car did not run long, I had to rebuild it after my mishap.
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Brett Foote Thread Starter
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From: New Jersey
Yea I know, I'm not running the motor now. I was really worried about bearing clearances but if it was a clearance issue, it would be a constant low pressure right? Yours was a brand new pump? Yea it's a brand new GM high volume.
I had 20,000 miles on the setup, pressure relief stuck. I pulled the pump, put a texas speed ported pump in. Ran fine for 1000 miles then oil pressure kept dropping to 25 at high rpm.
I would put a new pump and o ring just to be safe.
I would put a new pump and o ring just to be safe.
yup, there really isnt much too it. A pump , a gauge and bearing clearances. I doubt a clogged oil filter. You could try thicker oil and a new filter. I would lean towards bearings if this gets better.
Im having a similar problem... but mine doesnt read oil pressure at all... i started it up after a cam swap but it stays at zero. Oil filter filled up, took it off then started it again n it shot out oil so i assumed it was my sensor i replaced, took it off n started it again but no oil up top, took a valve cover off n clean as a whistle so no oil is going upstairs.
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From: New Jersey
Alright, don't mean to drag this out but I also have a brand new melling pump sitting in the garage. Should I change the pump as well because of a freak bad pump or its probably just the o-ring. I'm almost at the pump and want to make sure this thing isn't coming apart again.
@ StripedSS
Is the diverter plug (plastic barbell) in the rear of the block?
It installs in the oil gallery behind the rear cover (with it's o-ring to the rear), sending oil into the filter and then to the gallery that feeds the rest of the motor.
Is the diverter plug (plastic barbell) in the rear of the block?
It installs in the oil gallery behind the rear cover (with it's o-ring to the rear), sending oil into the filter and then to the gallery that feeds the rest of the motor.
Thread Starter
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From: New Jersey
Well got it all apart today. Slowly pulled the pick-up tube away from the pump and the o-ring was on the pump, not fully seated and somewhat pinched. I took it out, covered it in oil(which I didnt do the first time and probably why this happened) and straightened out the o-ring and it sat pretty flat. This time I pushed the tube up and tightened the bolt as opposed to tightening the bolt and letting it pull itself up. Hopefully ill be good to go this time.
