hello all,
got a 2000 ranger with a 4.0 ohv and recently has been rumbling on startup but goes away within 10 seconds. this seems to only happen when the truck is parked sideways on a hill because that's how i park at work and its only happened when leaving there. started asking around and have been told that the oil pump is having a "lose of prime" . got the flickering oil pressure gauge as well so the pressure always reads a little low most the time. after the rumble starts it has been reading lower than usual so maybe I'm getting low oil pressure? any feedback is appreciated.
Thanks

 

Check oil level, of course, if parked at an angle the oil pick up screen may be uncovered but ONLY if oil level is low

I would change oil filter just on speculation if this is a new issue, and of course add a bit more oil after changing

The oil filter should prevent drain back of the oil in the main passages when engine is off

Do the "Clear Flooded engine" before starting, I do this every morning on my high mile 4.0l, so it doesn't start dry
Turn on key
Press gas pedal down to the floor all the way and hold it down<<<this turns off fuel injectors
Now crank the engine, it should NOT start(no fuel), but oil pump will be pumping oil
While cranking count to 5 and then release gas pedal
When you release gas pedal injectors will start up and so will the engine

The oil pressure gauge is run by an ON/OFF switch on the engine, so its either 0 or "normal", 5psi pressure is the setting, so above 5psi gauge goes up
Any movement of the needle in the normal range is from the whole trucks electrical system, not the oil pressure
But the switch/sender can get worn out and cause needle to move around, so may be time to replace that switch on the engine
Drivers side of block toward the front, has a stand off fitting, and a 1 wire plug in, make sure the threads on the fitting and switch are clean, thats the switches GROUND so very important that it has a good ground to the engine block

 

checked the oil yesterday and it was at the proper fill level. thanks for the "clear flooded engine" trick. ill try using it at work to help prevent this from happening. I am going to replace the oil pressure switch today. i have replaced the switch last spring because the gauge did the flickering last winter as well and through the summer the gauge worked just fine. seems like when it gets down to winter temps the unit fails. I know its a common issue on these rigs but that common?
Thanks

 

No not THAT common

If you use "sealing tape" on the threads MAKE SURE you leave some bare metal at the lower end of the threads so they get a good ground, an intermittent ground will cause the flickering of the gauge

And "new parts" at not as reliable as they were in the past, unless they are Motorcraft parts they were NEVER tested before being shipped, yours were the first human hands to touch them, lol.
So "grain of salt" on trusting "new parts" made by 3rd parties, we WANT cheap, so we get cheap

Test Clear Flooded engine ahead of time, if engine does start with gas pedal down all the way then you have a stretched throttle cable, easy fix for that and you will get full throttle back
You just need to add a zip tie to the end of the throttle cable above gas pedal, this shortens the cable

Google: Ranger throttle cable mod