The past week, oil pressure has been steadily rising, from the r-m in normal originally, now runs at the L at an idle after start up, the edge of the box under a load, when I put it in gear, and is pegged after a few minutes of cruising at highway speeds. After cruising at highway speeds the pressure does not fall until idling for several minutes. Bought a new sending unit, but can't find it on the block, checked the entire drivers side, and all around oil filter, no wires, no sensor. Have been reasearching, apparently it is a on or off switch, that is activated between 4.5 and 7.5 lbs, but that does not make sense, as the guage is rising and falling with the rpm's. Also had a scheduled oil change three or four days after it started rising, used same brand and viscosity, as well as same filter. Pressure should be higher after oil changed, but it still should be lower than it is. Rest of the guage cluster works fine and accurate. Anyone have a piece of information or advice for me? I dont even know where to start to chase wire gremlins if that were the case...

 

The OP sending unit on the 460 is at the top center of the motor, all they way in the back behind the throttle body. It's possible a PO might have converted it to be a real gauge, as I have done on my '91.

 

Thanks for the input. I replaced the original sensor, and nothing changed. I said f*** it and put a wet gauge in its place. Pressure reads 70 lbs at cold start, 60 when warm and driving, and 40 at a stop and idleing. BEAUTIFUL, especially for 163k...

 

so even after replacing the op sensor, you still got a low reading? and what you did was replace the electrick sensor with at "wet" one and the oil pressure seems to have been good all along?

im having same "low" pressure problem and dont want to throw money and parts with out fully understanding it first. my problem started right after a oil change, which im partially blaming on a small STP filter compared to the size filter was there prior to oil change.

if this doesnt work the op sensor seems to be the next thing to look at. can you please tell me what brand u used, and where to replace it???

 

the factory guages are usually fancy idiot lights, i always replace them with an aftermarket direct reading guage. the oil pressure sending unit is on top of the block by the firewall in the center on a 7.5l 460

 

What did you use for a sender? Where did you get it? What was the part number?

 

I don't know the part number, I just asked for a sender for an '87 460. The '87 had real gauges. Be advised you must also put a jumper across the back of the gauge to bypass the 20 ohm resistor.