I have a 2001 ranger 4l, the oil gauge shows no oil pressure intermittently on cold days.( around 0 degrees) After a minute the needle fluctuates and then reads normal. The oil level is normal. I am using synthetic oil. Is this a gauge malfunction or oil pump or should I worry?
Thank You,
Barry

 

You will hear valve train noise if oil pressure drops below 4PSI, so if you don't hear that when needle is down then it is an electrical issue.

Ford changed to an oil pressure SWITCH in the late 1980's, on or off switch
The oil gauge has a resistor built in, so when switch is Closed gauge needle goes up to a predetermined position, when switch is open needle goes down to 0

Switch is set for 5.5psi oil pressure, above 6psi switch is Closed so needle is up, under 5psi switch is open so needle is down.

Any movement of needle when it is up is from alternators change in voltage as you REV engine, so not oil pressure changes

Usually the oil passage in the Switch on the engine gets clogged up or switch itself starts to fail, could also just be a loose wire on the switch.
Cold oil in the switch gets thick so doesn't show pressure until it warms up.
Oil Gauges do not usually have problems

You have the 4.0l SOHC engine in a 2001 Ranger, 2000 and older used the 4.0l OHV, these are different engines.

But oil pressure switch was in almost the same place on both engines, drivers side just above oil pan toward the front.
Access thru drivers side wheel well, remove lower liner and you can see in to where switch is located

 

Hi Ron
Thank You for your reply. An Update to the oil pressure gauge problem, the gauge now does not come up at all and there is a lot of noise from the engine. I have only run it in idle and 1/2 mile trip. Before this the engine made noise but went away as soon as the oil pressure gauge returned to normal. Now the gauge never returns to normal and the sound does not go away. I am afraid to let the engine warm to normal operating temperature for fear of more engine damage. Do you know what will fix this?
Regards,
Barry

 

Yes, do not run the engine, it isn't a gauge/switch issue if engine is making noise

I would first change the oil filter, could be bad or clogged

Before trying to start:
turn key on
Press gas pedal down to the floor and HOLD IT DOWN all the way
Turn key to START

Engine should turn over but NOT start
Fuel injectors should be OFF

Crank engine over a few times to refill oil filter

Release gas pedal(turns injectors back on)
And start engine

Shut engine off immediately if gauge shows 0 and you hear the noise again

If this doesn't get oil pressure back then you will have to do some disassembly

 

Hi Ron
I did change the oil filter and presto oil pressure returned and noise went away. There was frozen water pieces in the oil that came out of the old filter. We had below zero temps for 2 weeks. Thank You so much, you made my day
Regards,
Barry

 

Good Work

Thanks for posting the fix, it will help others down the road

When it warms up I would look at changing your PCV Valve, it may have frozen up as well which raise the condensation level in the engine, water in the oil
If you take off oil filler cap and look at the under side and see white oily residue thats condensation build up
In some northern areas engines come with heated PCV Valves