What does it mean when u have a little oil leak and your oil light only comes on when your car idles

You need to find out why you have low oil pressure. It is normal that as engine rpm's increase, the oil pressure will rise- the oil pump is moving oil faster. Even though your light goes out, you could still have critically low oil pressure. There should be sufficient pressure at idle to keep the light off. The light will come on when your oil pressure is almost nil- I believe for some it's as low as 8 psi. Normally, oil pressure at idle is specified anywhere from 15 to 40 psi. You would have to check specifications for your Expedition. To verify oil pressure, hook up a mechanical gauge at the oil pressure sending unit on the engine block. Check with a local shop.

The causes run from easy, simple to budget busting ruin. Low oil level, wrong grade oil, real old oil, oil leaks, internal oil leaks, worn oil pump, worn crankshaft bearings. It was pretty common on older very high mileage cars to have a fluttering oil light at stops and idle. It was time for a rebuild, or time to look for another car.

How's the motor look around the valve covers,just because the oil light comes on doesn't mean the only problem is low oil,could mean low oil pressure,which is caused by many reasons.

the sound might be coming from the tappets.

Your problem is not the oil pressure sensor, it's because your idling is going too low. If you raise the RPM slightly the light goes out. 650rpm is a little low. I think your car has an Idle control valve ... or look if it has an Idle position sensor. I suspect you have an issue with that.
Hope this helps.

Sam

Oil pressure is always lower at idle speed.I'm guessing you have high mileage.If your oil light is not coming on in drive at idle with the engine cold,but it does when hot,your bearing clearances are probably getting a little loose.Try using one quart of Lucas oil additive in place of a quart of oil at your next change(or just change it now).This stuff is thick and stringy,it helps the oil cling to surfaces.(if there is no change after this,you could try a new oil pressure switch-it's cheap enough.I actually had the switch on my 95 dakota leaking a LOT of oil at high pressure/RPM,which affected the reading).

A car cannot idle when you are driving, the term "idle" is only used when the car is stopped and motionless. You mean the the car's RPM's are at 2000 when driving at 40mph. The RPM's are normal at that speed and you cannot change it unless you change the gear ratios inside your Transaxle.

The smell you are referring to may be a oil leak of some sort, you may need to look on the ground after you are parked awhile and see if there is fluid leaking and try to determine what type of fluid it is so you can trace what component is leaking.

oil pump

look for the oil light switch ,then see if it has a rubber boot over it ,if it has pull it back and see if any oil inside the boot .If their is renew the oil light switch its leaking a little and the oil inside the rubber boot is causing the light to come on

Since you are going to check the one way valve and cleaning the filter too, I would recommend to check the intake air filter and clean it throughly. After that use carb cleaner to free up the nozzles of the injector valve . If the engine sound better after using carb cleaner, add some into the fuel from the fuel filter or pump, whichever one has easy access, and gun your engine in short bursts, after which it should run better.........sodeep

there ia a seal/oring on the dist shaft it should not leak that bad look for a sensor near by wash with brake cleaner let idle and wash let me know ok tell fix ya bout me