View Full Version : Oil pressure needle jumps.

04-29-2017, 03:02 PM
22 Classic with stock 1996 Gen 6 502 Mag. Oil pressure alarm going off at about 25psi at 2000rpm. Sounds like plenty of pressure to me. New VR1 20-50 right at full line, new Wix filter. Pressure at 25-40psi which sounds good but needle jerks back and forth from 25-30/35 for seemingly no reason. Sender issue? Running great, no overheat, no steam, all else normal.

Did it late last season and now on this first run this season with new oil.

Thoughts appreciated..


John C in PA
04-29-2017, 04:34 PM
Loose wire on instrument or sender. Maybe sender going bad.

John C

Kenny n.
04-30-2017, 12:28 PM
Some times the oil sender ruptures internally. Remove it and if it feels heavy that is a good sign. As said before first check the back side of the instrument panel for loose wires even on the ignition switch.

04-30-2017, 01:11 PM
Your gauge and alarm will not use the same sending unit. The alarm will typically use a pressure switch and not a variable sending, like the gauge.
If your gauge is fluctuating and your alarm is going off, my guess is your sender and switch are working fine so you may need to look elsewhere.

25psi is enough pressure and should not trigger an alarm, but if your gauge needle is swinging, your pressure very well could be dropping much lower than that, if it happens too quickly for the gauge to respond.

With 20/50 I'd expect the pressure to be higher. Not sure where I'd start to look. Because everything was ok when you put it away and all you did was an oil change, maybe you got a bad filter??

EDIT: Reread your post and it sounds like this was happening at the end of last season before the oil change also. If that's the case, then it sounds internal to me. Worn pump, loose pickup (sucking air where it mates to the pump), or worst case worn bearings.
To completely rule out the sending unit(s) I'd pull out one off them and install a mechanical gauge and see what it reads, then go from there.

04-30-2017, 01:30 PM
Engine wiring harness for 502. Note: The pressure switch and sensor is labeled incorrectly. "Switch" is for audio, "sensor" is for instrumentation.

I have the entire service manual in pdf, if you want a copy. (I'll need your email, as I can't send it through donzi.net)