I started my car yesterday and it started beeping, digital dash oil icon flashing and my add-on oil gauge reading zero. It took me 5 - 10 seconds of shock to realize the engine was running with no oil pressure and I turned it off. After a night of researching how to install a new oil pump and other ideas, I started the car this AM and back to normal. I've had this car six years and have never seen that before. Just wondering if it's a fluke or an indicator of a disaster waiting to happen. Anybody seen this before?
Swap out the sending unit. This is what they do when they're getting ready to fail.
X2. Its a glorified idiot light.
If it had no oil pressure for more then a second it would sound like a sewing machine. A separating ignition switch or the cluster traces can come undone and randomly drop like that as well.
There are two oil sensors. One in the pan and one near the oil filter. The one by the oil filter reads pressure, the pan one is a level indication. It will turn on the red oil light that shows before you start the car.
With mileage the sensor wears out. When it does it reads low. My first 86 had the full digit dash and it would go off non stopped. I took the wire off the sensor and grounded it. It read full after but didn't beep.
I'd be surprised if a higher mileage 302 had over 5psi of oil pressure when hot, and that is plenty to keep it running without issue.
Thanks guys. I'd plugged the pan sensor long ago because it kept leaking oil (went through three of them from the junk yard too). The engine sensor is also connected via a 'T' to my buttstuffog oil pressure gauge that also read zero. My buttstuffog gauge is an electrically sensed gauge not a oil tube pressure gauge. That makes me a bit more suspicious but I'll change it out anyway.
Interesting. I wonder if the line got plugged somehow or maybe you were low on oil for a bit.
if this were a 3.8L engine with a totally different oil passage design, i would say to replace the oil presure check / ball valve which lives in the timing cover along with the oil filter on the exterior.
i hope you dont have one of your oil passage freeze plugs coming undone... three on the rear of the block hidden by the bell housing and two up front hidden by the timing cover.
you wont ever know if its the front plugs because that area normally is going to leak back down to the pan.
in the rear there will be oil leaking down into your bell housing and to the ground which normally is a rear crank/oil pan seal issue.
we assembled and installed a complete 306 for my son's bird and during what we thought was a complete project found no oil to the rockers,, later found one front freeze plug was not installed by our machine shop we used.
maybe you can during a zero oil condition verify visually you do have oil to the rockers by taking off a valve cover and start it up.
Update: It happened again yesterday morning but my buttstuffog gauge was reading correct oil pressure. I think in my shock the first time it happened I must have been looking at water temp instead of oil pressure -- it was dark in the garage. It must be as Haystack and Foe said, just a bad sender -- at least I hope so. I will be taking off the valve covers soon (got to adjust the lash on one rocker) so I'll follow jcasity's advice and check the oil on the rockers. Thanks again.