The other day my oil pressure game went to low. and you can tell it's not getting oil because you an here it in the motor. Sometimes when i first start up the truck it had oil pressure just fine. After driving for 10 or so minutes it drops to nothing. But if i shut off the truck and start it back up it goes right back to normal.
I'm not sure just when Ford went from a "real" oil pressure gauge to a idiot light with an analog readout, but it probably was late 80s for the truck lines. If there's a button type sender at the oil pressure output port, it's a fake gauge that closes a switch around 7 psi and then reopens it at say, 5 psi. Put a mechanical gauge on the oil pressure port and see if the readings are consistent with the factory "gauge". If so, you have problems, ranging from a dirty sump (oil pickup screen gets clogged) to worn main bearings or crankshaft. If not, it's the gauge itself, the sender, or the sender wiring.
No, they had idiot lights back in 1949 or so; I'm talking about the fake gauge that's driven by an on-off switch like the idiot light, but appears to be an actual needle-type gauge. That piece of trickery didn't happen until the late
1980s on Ford trucks, and Ford-made cars with apparent gauges in the early
1990s.
Well I have an '82 pickup or bronco, or an 89 pickup, take your pick, with a factory idiot GAUGE, not the light! If you need a picture the gauge and it's sending unit, I'll gladly post if on a binary Usenet group for you. I don't have my 71 truck anymore, The oil pressure gauge in that one may have been after market.
Check the sender on the '89. It's most likely the button-type, and the "gauge" in the cab is a fake. If it is a button (snap-switch) sender, look at one of the Ford truck websites for a how-to conversion to a real gauge, or if it doesn't bother you, do nothing.
With the audible noise, likely the gauge is NOT lying to you. As another poster told you, probably sludge is being sucked up to the oil pump pickup screen & causing engine to starve. Shutting off engine allows sludge to 'fall away' from the screen & let pressure go back up when you next start it--then the cycle repeats. Some will say to have pan removed, remove & clean/replace screen/oil pump/oil pan. Much quicker, cheaper, and quite effective procedure would be to drain oil on Friday evening. Replace plug. Pour in 4-5-6 qts.--equal amount to # of qts of oil it takes-- of carb cleaner (the kind that is used to soak entire carbs in). On Monday evening, drain oil pan COMPLETELY. This brings out now-diluted sludge along with the carb cleaner which has now washed the pan & oil-pump screen and to some degree, the pickup tube. Replace plug & refill with oil and change oil filter too--just to say you did. Drive truck for few minutes until it reaches full operating temperature, bring it back and change oil & filter again IMMEDIATELY WHILE STILL HOT. Problem solved! It works, I know, 'cause I've done it several times! Donate $ saved to your local church/charity. s
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