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Hello, just changed the oil on my 1996 Chevy Silverado 4.3L
I've done this oil change on this truck prob a 100+ times. After this time tho, my oil pressure gauge is reading weird. It's settling high and ending up high. My oil pressure gauge has always followed my rpms, when I idle, it settles, when I am driving, it's rising. I was thinking maybe I got a bad filter? I've changed the oil pressure sensor sending unit a few years back. So its not the original.
Any ideas? I've got all the electrical probes and such to do some detective work.
I was thinking of maybe just changing the oil again and putting another filter on. Cheapest thing to try first.
My first thoughts would be a different viscosity oil would do that or a funny filter maybe. Especially if it happened right after the oil change. If you have an oil pressure gauge tool you can check it with that. Also a couple of other tests can be done at the sensor.
I'm going to change the oil and filter again in a few days and see what happens. I'm letting the truck warm up right now and then see what the gauge is reading.
I don't have an oil pressure gauge.
What tests can be done at the sensor? Voltage drop?
Did you notice that the pressure was still higher at operating temp? Does it over all read higher or is it fixed at a level?
With the key on, the orange wire at the sensor should have power, and it looks like the gray wire should too. The tan wire goes directly to the instrument cluster and the sensor grounds to the motor where it is installed.
If you disconnect that sensor, the pressure gauge on the cluster should go high (high resistance). I'm not sure if there is a resistance table somewhere that says what psi equals in voltage. I'd probably expect 5v on that connector with it unplugged and some amount less than that plugged in. If it seems shifted high, then there could be excessive resistance on the tan wire. I'm not sure if a bad ground there could cause this.
If the wire integrity is good, then either the sending unit is bad, or it's telling the truth and the pressure is higher. That's where a mechanical gauge would come in handy.
Maybe someone else has more ways to determine if it's telling the truth. Maybe applying x amount of pressure to the unit and see if it corresponds with the gauge on the cluster?
If it is very high my first thoughts would be a stuck oil pressure relief but that dosen't really fit with it happening just after an oil change,
I have seen cannister type oil filters explode due to sticking relief valves.
Probably the simplest diagnostic is to spend 25$ or so on a cheap chinese oil pressure test gauge kit that will instantly tell you if the issue is electrical or mechanical alternatively take out the sensor and use air pressure --- even a a foot pump should produce a signal but the sensor body will need grounded
" We're trying to plug a hole in the universe, what are you doing ?. "
(Walter Bishop Fringe TV show)
So the truck warmed up to operating temperature and the pressure returned to normal.
Any ideas? I think I'm going to just forget it about it and move on if its settling at normal once the truck warms up. Betsy has 380k miles all original engine/transmission lol. Had the truck since 30k hehe.
And to your question, was the gauge all over the place or steady, it was steady. It was operating fine, but everything was on the higher side while the engine wasnt yet at operating temperature.
I've never had it be different, operating temperature pressure and non-operating temperature pressure. Thats why I was like WOAH WTF! LOL I got home as quick as I could thinking my truck was going to explode
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