vipergtrdj

Curious what everyones opinion is ....
500 miles on rebuilt lq4, ported and shimmed oil pump, delete bypass in pan, new oil pressure sensor, new oring (double checked after assembly to make sure it wasnt pinched). Before rebuild the oil pressure was 20psi idle, 40psi WOT. Now it's 50psi idle, and stays 50psi at WOT according to factory gauge. I haven't put a mechanical gauge on it to confirm readings yet. Plan to do this weekend.

What would cause it to stay 50psi regardless of rpm?

1FastBrick

iTrader: (17)

Sounds like a stuck bypass in the oil pump.

MikeGyver

iTrader: (5)

My opinion is that the spring in the pump opens at 50 psi, because it seems like if it was stuck open, the bypass would act like a fixed orifice and oil pressure should vary with engine speed.

vipergtrdj

The spring for the bypass opens at 50psi ? Can I get to the spring by dropping the pan? I cant remember.

kbracing96

iTrader: (26)

You rebuild the motor, your clearances are tighter needing less oil volume, the oil pump is ported so it's flowing more. So it always out flowing what the motor can uses at idle and at speed. It's just alway in some form of bypass witch is 50psi. I don't think there is anything wrong with it.

vipergtrdj

Even when its higher rpms , say 5k or so, and it stays at 50psi. That sounds fine ? I've read others with ported and shimmed pumps hit 65 to 70psi. I just find it odd that higher rpms is same as idle.

vipergtrdj

Threw 2 different mechanical gauges on it, an Autometer and this no-name gauge both registered the same. Looks like warm idle is roughly 35psi, at 15seconds in the video at 5000rpms it hits 75psi at the fitting by oil filter on the pan. So I can only imagine the oil pressure sensor is bad or the gauge cluster. Anyway of testing the cluster or sensor ?

1FastBrick

iTrader: (17)

Cluster can be tested with a Tech 2 or equivalent Bi-directional tool.

With the same tool, you can also watch sensor input.