/ What does "oil - low pressure" light mean when it just barely starts coming on? #51
- Feb 19, 2011
- Bolton, MA
- 1983 Ford 1700, 4WD, 770 Loader, Woods backhoe, Woods brush hog,etc.
Hi JC.several things could cause it.
1- Your oil sender unit is defective or close being defective. Sender is a normally closed switch by action of an internal spring. Upon start up, it maintains a closed circuit hence oil light pressure illuminating. As soon as pump start pumping oil, then the oil pressure will opens the switch and then oil pressure light will go out indicating pressure. Now this is for only "idiot light". The sender could also have a variable resistor, calibrated to digital or analog(needle) that actually shows pressure. This one is more preferable but mainly used on some automobiles more so than tractors.
2- If your oil level is low and you are in an incline (up or down) then you oil pick up tube and screen might suck some air while pumping, causing the pump to cavitate a bit, not making pressure and illuminating the low pressure light. A partially clogged screen can cause that and to clean that engine pan needs to be removed.
3- There is a very low possibility that your gear driven oil pump is damaged or has some restriction. This is very seldom a root cause but there is a possibility.
4- Check for loose wiring at the sending unit and also check all the fuses. Also check the connection at the back of tachometer.
By the way, I had to change my oil sending unit once 15 years ago. It was stuck closed.
Coming back to this original post topic of the "oil pressure" light flickering under load. Just to confirm, (I'm 99% sure but need to confirm), the idiot light in my tach/mph is for when the oil pressure is too low, correct? I just changed my oil with Rotella & new filter and made sure the dipstick confirms proper fill level, which it does. Almost immediately, the oil pressure light is beginning to flicker when it takes on even a moderate load. I drove sideways across a gentle slope, so the machine was tipped mayyyyyyybe 10-15 degrees. It is hot as you know what out... Just weird that having owned this machine for about 10 years, I've never seen this issue.
I would have thought if the wiring or sending unit or any part of the overall apparatus was bad, it would either work or not work - not gently in between. Any thoughts/ideas?