Thread: newly rebuilt motor poor oil pressure?

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newly built 383 stroker showing poor oil pressure this ones got me . im not a rookie builder motor has new scat crank & rods bearing clearances all .002-.0025 oil galleys tapped for pipe plugs first thought pump releif was stuck dropped pan and swapped in hi volume pump , no improvement lifters wont pump up & oil at idle drops to zero this one got me. any ideas ?

oil pump drive shaft in place??

oil pump shaft is in & prelubed with drill motor

Just a thought, but is the gage accurate? Something in the oil line to the gage (Mechanical)? Maybe the buypass for the oil filter not working right? Does the engine sound like low pressure - lifter noise?

oil pressure guage good mechanical , motor not pumping up lifters , unable to adjust lifters due to lack of oil pressure . very little oil coming out of pushrod/rockers . oil filter bypass was clean and working . changed filter thinking i had a defective one . this ones got me.

Originally posted by tedsmotoguzzi
oil pressure guage good mechanical , motor not pumping up lifters , unable to adjust lifters due to lack of oil pressure . very little oil coming out of pushrod/rockers . oil filter bypass was clean and working . changed filter thinking i had a defective one . this ones got me.

Just grabbin' @ straws, but when you spin the pump with a drill do you get any signs of pressure or does the drill have drag on it like it's pumping oil?

I guess what I'm getting at is the pump is the source, so I would make sure the pump was working first. Once that is established then trace it down the line until you find the restriction or whatever the problem is.

Could there be a restriction in an oil galley somewhere?

Just trying to think of possibilities ?????????????????

Silly questions:

- Does the distributor engage the oil pump shaft? Arent there a couple of different length shafts?

- Does it pre-oil when you run the pump with the drill?

- Do you get oil in the filter when you turn the engine over? If you do, the problem is downstream of the filter.

- Are all of the proper galley plugs installed?

- Is the pickup submerged in the oil? Wrong pickup length sucks air.

if you dont have a restiction like pro says then a open in the oiling system would do the same thing. if you left a main bearing cap loose then you would loose most of your pressure there. so while your looking for a restiction look also for a open. a plug in the oil gallery left out. main or rod bearing cap loose. if a lifter comes out of a lifter hole you lose most of your oil pres. oil pump loose, or pick tube has a hole in it. did you put in new cam bearings? i think you can put the cam bushings in wrong and loose the oil pressure. not saying anybody did anything wrong but these are some of the things i would look at. ive been told if you have a problem go back to where you just went and most of the time youll find the problem, and it been true most of the time. do like pro said take the drill and turn the pump again and see what happens. oil should come out of the push rods that way like it would with the motor running, but if its not you might can hear where your loosing your pressure

Originally posted by tedsmotoguzzi
...... drops to zero this one got me. any ideas ?

You're kinda skimpy on info here, but your use of the word drops implies you have some pressure reading above idle.?

If you answer Henry's questions that would eliminate a couple variables. The other posibility is the pickup is too close to the bottom of the pan and can't pick up oil as it should. The other concept to keep in mind is there is a difference between flow and pressure. If you have flow but low pressure, you've got problems with adequate supply or excessive leakage. If you've got pressure and no flow, then you've got restriction after the point where you're measuring pressure. Or if you have some flow, but poor pressure, then the restriction, if there is one, would be in the system before the pressure sensor.

yes the drill motor has drag on it & guage shows 20lbs , but at idle speeds pressure drops to zero or near. i pulled 8th inch pipe plug at front of motor, bumbed drill motor & oil shot , Yet no or very little oil is coming out push rods , valve train is very loud. oil galleys were tapped for pipe plugs & installed . pick up is new & 3/8 to 1/2 inch off botom of pan . Im a machinist & installed cam being myself cam turned freely & care was taken to witness oil passages, if there a fault it eluding me . im getting nervous to pro tenial crack in lifter galley. trying every opion before disassembling. on 1st oil priming it did seem like something let go, i thought i heard oil pressure escaping.

primed oil pump.=pick up bad....cam bearings.....off clearance.....

Oil pickup to long, touching/sucking the bottom of the pan ?

Originally posted by tedsmotoguzzi
yes the drill motor has drag on it & guage shows 20lbs , but at idle speeds pressure drops to zero or near. i pulled 8th inch pipe plug at front of motor, bumbed drill motor & oil shot , Yet no or very little oil is coming out push rods , valve train is very loud. oil galleys were tapped for pipe plugs & installed . pick up is new & 3/8 to 1/2 inch off botom of pan . Im a machinist & installed cam being myself cam turned freely & care was taken to witness oil passages, if there a fault it eluding me . im getting nervous to pro tenial crack in lifter galley. trying every opion before disassembling. on 1st oil priming it did seem like something let go, i thought i heard oil pressure escaping.

dont belive a crack would loose all that press. i belive if you go back into he motor youll find it. shit happens! to the best

Sounds to me that you probably spun your cam bearings. Had that happen to my motor when I first started it up. The 3 center bearings were all spun and the middle one was so bad it was sitting in the oil pan. My cam was ruined and had to get the block line bored for oversize cam bearings.

tonights work had me double checking pipe plugs in rear of block. thought i might have secrewed plugs in to deep & blocking the oil or restricting the oil enough to cause this headache. but plugs checked out ok. im disassembling motor and will fess up if it is my mistake. been at this game long enough to know you dont get hurt sittin on the couch. will post game results when resolved.