hi all, new to this forum but here goes. recently purchased f150 6cyl. runs great, but when it really gets warmed up 10 or 15 miles or so . the oil pressure guage needle will vibrate all over the dial. all other guages are fine. it will only vibrate at a stop lt. or something when in gear. put it in N and its fine. apply the gas in gear to go and again its fine. happens only when stopped in gear. I don't have a clue. any help greatly appreciated. regards, tony

 

Welcome to the forum! My guess it that oil pressure sensor can't "deal with" low pressure while idleing in gear.

 

thanks hampster, I'll try replacing the oil pressure sender and get back with results. tony

 

Had a buddy who assumed when his oil pressure dropped that it was the sending unit too, he went across the Memphis bridge JUST past the point of no stopping (no more shoulder) dropped again and started knocking. Was knocking pretty good 2 miles later when he got across. Yep the oil pump tube's screen (after the sump in the tube) was totally stopped up. Do you really eant to assume sending unit? Or do you want to drop the pan and check your sump/tube?

 

Leaning toward a problem w/ p/u or pump itself. Although replacing the sender first is a cheap & easier date & may pan out for you. If the P/U is clogged, you probably have a sludge problem systemically. "Seafoam" is your friend! You might very well see a improvement change in gauge behavior after adding it to your oil. If that's the case, it would also mean an improvement in flow.

Or do this:
Connect an oil-pressure gauge in place of the oil sending unit.

Start the engine, ask an assistant to rev up the engine to 2,000 rpm and record the gauge's oil pressure reading.

Let the engine warm up for about 20 minutes, ask your assistant to rev up the engine again to 2,000 rpm and record the gauge's oil pressure reading.


Compare your pressure readings to specifications. Oil pressure should be between 40 and 60 psi at 2,000 rpm, perhaps a little bit higher, with the engine cold. And between 40 and 60 psi at 2,000 rpm once the engine has reached operating temperature. If your readings are out of specifications, time to drop the pan!

 

it's not that the pressure is low or drops. when starting cold the needle will stay at botton for 2 sec or so and spring up to mid-guage or and run there all day long unless you stop for a lt. or something and it then swings wildly from low to high end untill you start off again and its instantly normal. trying a new sender today and will let you know results. tony

 

You're only assuming w/o seeing a PSI gauge read. But a new sender might just solve the problem if not actually pressure related.

 

success, new sender solved all problems. Hampster's 1st reply was right on the money (thank God) thanks all for your suggestions. I'me glad it was nothing more serious. regards, tony

 

I suspected your sender as well...

Ive had the sender act up on other cars too and they all do the same thing.. they 'jump around' -- erratic spikes and wierdness that happens too fast to be the result of engine RPMS...

glad it was only your sender!

It is human nature to think 'the worst' when it comes to beloved cars, but typically it's never as bad as you think (unless has a serious history of nigglect)