Oil Pressure problem at idle

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js1023

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First off I want to thank everybody for input and there guided service of helping rebuild a motor. So Good news the motor runs great smooth as can be. Now, I put it in gear today and went to take it around the block nice and slow. As i was sitting at the stop sign the oil pressure dropped down to about 5lbs. Does anybody have any suggestions on what to do?

I still have to take the timing light to the timing because you can tell the timing is off but, timing doesnt effect the oil pressure at all or does it when it brings the idle up.

When i start the car and leave it in park the i am pumping 50lbs plus, when its in drive and stop sign i loose pretty much all that oil pressure. Give the gas it has no problem picking up pressure.

I am just looking for input and advice in this matter. Thanks for the help again and I hope its a small problem
 
This is a hard one to answer because so many opinions vary when it comes to oil pressure. I have had several engines that ran and lived very long lives that had 8-15 lbs of oil pressure at hot idle.As soon at you tapped the throttle they would jump right up to 30-40 lbs and stay there at anything above idle.One was a fresh 360,, 10 years and still running..These were hydraulic cam engines and the lifters never were starved for oil at idle.So take it for what it is worth.My new 2010 work van has about 8-10 lbs of oil pressure hot and less than 30 running down the road,drives me nuts having to look at the gauge when driving.Do you run a gauge and a light? I ask to see if the light comes on or flickers at idle? some light sending units are set to as low as 2-3 lbs.Sorry for the long post but trying to think of possible problems and cause.
 
The old rule of thumb is 10# per 1000 rpm. I helped my hot oil pressure by using a quality Wix filter instead of a Fram.
 
moper said:
What is the idle speed in gear? Out of gear?
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The oil pressure drops at idle in gear...for example i was sitting at the stop sign for about 8 seconds it drops. I do not have a lighted gauge..but it looks as if the gauge is almost down to zero drives me nuts haha
 
Most likely bearing clearance, flaked cam bearings, wore rods and mains
 
Mr Hemi said:
Most likely bearing clearance, flaked cam bearings, wore rods and mains
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Everything was recently replaced new cam/main/rod bearings. all holes were lined up and everything was put back to standard build.
 
What type of gage is this? Factory electric? does the light come on? Is it a mechanical gage with numbers?
 
what idle rpm in gear?

I have had washed out bearings from a no clean after machining and still had 18-20psi in idle 'hot', grooves so deep and wide you could sail a boat down'em...
 
If it's a stock oil pump, drive it like you stole it. It's fine.
 
moper said:
What type of gage is this? Factory electric? does the light come on? Is it a mechanical gage with numbers?
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I jus upgraded to an aftermarket 10$ gauge from advanced auto parts still reading below 10lbs after sitting a while/

caferacerx said:
and what weight oil are you using? regular or synthetic?
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10W-30 Valvoline conventional..is that thick?


StrokerScamp said:
If it's a stock oil pump, drive it like you stole it. It's fine.
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Its a regular volume replacement.
 
sounds like motor has alot of clerence in the bottom end put a bottle of lucas oil addative in it and see if it inproves..Artie
 
What brand of oil filter? What brand of oil? I'm more inclined to say it's a gage issue more than a problem with the engine. 10psi is fine at idle. But, in ny opinion anyway, it shouldn't go below 10 even at a 600rpm idle speed. You can also upgrade to a 15-40 fleet grade oil. It will help guard better against cam failure and the oil pressure will increase accross the board.
 
Low oil pressure makes me a little nervous. Because it is a newly rebuilt engine, I would pull the pan and put a higher pressure pump in there. I wonder if the oil galley plug in the block (inside the rear main web) is loose.
 
As long as the needle is off the peg at idle, you're good. I every single book whether factory or otherwise, oil pressure spec is not given at idle. It is usuallygiven at 2K. If you have at least 20 psi at 2K, and there are no metallic particles in the oil when you change it, drive it like you stole it.
 
StrokerScamp said:
As long as the needle is off the peg at idle, you're good. I every single book whether factory or otherwise, oil pressure spec is not given at idle. It is usuallygiven at 2K. If you have at least 20 psi at 2K, and there are no metallic particles in the oil when you change it, drive it like you stole it.
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That' pretty much it. With good clearances I can get 10psi turning the pump by hand...
 
Any chance you missed the plug at the rear of the oil galley (I call it the plug inside the plug) at the back of the motor?
 
moparmaniac69 said:
Any chance you missed the plug at the rear of the oil galley (I call it the plug inside the plug) at the back of the motor?
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Then he would have zero oil pressure all the time.
 
I had the exact same problem with my newly rebuilt engine. Great oil pressure while driving when hot, but it would drop below 10 psi at idle. The fix was as easy as doing an oil change and switching to Rotella 15-40. Now the hot pressure is right at 15 psi. Worth a shot.



Correction: Went for a drive today and paid close attention to the oil pressure. Hot oil pressure at idle stayed between 19-20 psi.
 
UOP said:
I had the exact same problem with my newly rebuilt engine. Great oil pressure while driving when hot, but it would drop below 10 psi at idle. The fix was as easy as doing an oil change and switching to Rotella 15-40. Now the hot pressure is right at 15 psi. Worth a shot.



Correction: Went for a drive today and paid close attention to the oil pressure. Hot oil pressure at idle stayed between 19-20 psi.
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I am do an oil change and try it out. I will give you guys an updated status!
 
UOP said:
I had the exact same problem with my newly rebuilt engine. Great oil pressure while driving when hot, but it would drop below 10 psi at idle. The fix was as easy as doing an oil change and switching to Rotella 15-40. Now the hot pressure is right at 15 psi. Worth a shot.
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Agreed. If you don't drive in very cold weather, run 20W-50 conventional oil and a GOOD oil filter - Wix, Mobil1, K&N...

If you run a flat tappet cam, a zinc additive wouldn't hurt. Not for oil pressure, but for cam lobe wear.
 
fourspeed said:
Agreed. If you don't drive in very cold weather, run 20W-50 conventional oil and a GOOD oil filter - Wix, Mobil1, K&N...

If you run a flat tappet cam, a zinc additive wouldn't hurt. Not for oil pressure, but for cam lobe wear.
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I run 20w-50 oil and get 30 lbs at 800 rpm hot in my 340. 70 to 80 ice cold at rpm's and a good 60 lbs and 4,000 rpm and stays there when motor is hot.

Back in the day Mopar said to run 20w-50 for all hp driving, even in the winter
 
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