TR3driver
Great Pumpkin - R.I.P
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Years ago, while I was overseas, the wife called to say the oil pressure gauge in the family grocery-getter would rise just a little when the engine started, then fall back to zero. Had her take it to a local shop, who told her the engine had to be replaced immediately and likely wouldn't even make it home otherwise. He also said the car wasn't worth even a used engine (which was probably true at his rates).2wrench said:Hope and ignorance says to do the small, easy and inexpensive stuff prior to ripping
into the bearings and the like. Wouldn't I feel beyond ignorant...
Couldn't afford a new car at that point, so when I got home I promptly dropped the pan (which on that car meant also disassembling part of the frame and front suspension). Oil pump pickup fell out in my hands, so I assumed that was the problem, stuffed new bearings in and buttoned it up.
Imagine my surprise when the oil gauge did exactly the same thing! Sure enough, bad OP sender; the diaphragm was leaking oil into the chamber where the variable resistor lived. At startup it would take a few seconds for the oil pressure to equalize, so the diaphragm would deflect and cause the gauge to rise, but once the pressure equalized across the diaphragm, the gauge would read 0. And the ONLY external indication of the problem was a ring of oil around the terminal.
So I'm a real believer in checking the easy stuff first, even if it is unlikely. (Not to mention not trusting "professionals" to know a bad engine from a bad OP sender.)