The Stovebolt Site Forums The Shop Area Engine Shop Oil pressure up in overdrive

56 3100 235 column shift w/overdrive. My oil pressure fluctuates 30 to 55 when I drive in overdrive, but stays steady 30-35 driving not in overdrive. I never noticed this happening before, maybe it's always been that way, but Is that normal? Can't imagine that driving in overdrive would have that kind of affect.

Dale

It wouldn't have effect on the oil pressure itself. If the gauge is electrical it could effect the operation of it. Could be a bad ground between the engine & body or the instrument panel. If it is a mechanical gauge I can't imagine how it would effect it. Hook up a master gauge & try it.

Well your foot doesn't have a constant pressure, the terrain is a constant variable. The best move I ever made was to install a Vacuum gauge, completely changed how I drive my '49 1/2 ton with a '69 3sp+od. I spend MUCH less time in od, I just pay attention to 'the green zone' the area of greatest efficiency.

Well it looks to me like I have a mechanical oil gauge. Tube travels from a combined oil filter hose/oil gauge tube fitting at the base of the engine to the oil gauge. Don't have a "master gauge" and a quick call says flaps don't carry them either - kinda laughed at me "old school" he said, "try Snap On". Must be a specialty tool? Unless I'm missing something (entirely possible) and that oil gauge is still somehow electrical (it does seem electrical would be the only way the reading would differ od to not od, as you said). So I will start checking ground wires again. Have had that trouble in the past. Thanks for the help! Dale

You know Cosmo, what you say makes a lot of sense. I am not overly fond of OD unless I am traveling farther and want to go faster. For that it's great. Around here locally, most of my driving is just local speeds, and I like the feel of the engine helping me slow down when I'm off the gas pedal. Don't know why, I just do. Lots of vacuum gauges out there though. Are any of them better or all pretty much the same? Only want to do it one time so should get a good one. Thanks for your thoughts ---- Dale

The joke is on the guys at the FLAPS! The gauge Cosmo is referring to is simply an aftermarket mechanical gauge- - - -I'll bet they have one right on the shelf! Just disconnect the line going to the dash from the T fitting on the side of the block, plumb in a new gauge line temporarily, duct tape the gauge to the windshield wiper, and go for a test drive. Then check to see if the pressure reading is the same with the new gauge!
Jerry