Just picked up a 1998 F-150 Supercab 2wd Automatic. Runs great... But now I have the dreaded flucuating Oil pressure needle. I see that this is a common problem. I have changed to oil today and this is seaming to work. I have ordered the sending unit and it should be here Tuesday. If i have to replace the oil pump. Do I need to pull the timimg cover and camshaft and all that other crap. Or is that just on the 4.6 and 5.4? I have an Chiltons book to 1997 and it says I don't need to but is the 1998 different? Knowing my luck it is. Thanks for looking.
The 4.2 is fundamentally the same from introduction throught final production.
Some differences in intake setup, elimination of a temp sending unit, a change over to electronic throttle body, that type stuff. But, the long block is pretty much the same across all years.
The book you have should closely match your model year in that regard.
hi,the oil pump is on its own and easy to remove. take care when removing as the drive spindle is thin and has been know to break.
sorry but i have to ask, was there any sign of antifreeze in the oil when you did the change because i also found doing the oil change made a difference but later contamination with antifreeze made the pressure gauge fluctuate again. bokker.
The oil was very thin(I thought). It seamed to run off the dipstick. I saw no trace of water in the oil. I know in the past I have had water in the oil and the oil looked milky gray. This oil had good color just thin. I replaced it with 10w30 instaed of the reccomended 5w20. This seamed to helped the oil pressure. I think that the Oil Pressure Guage may be an actual guage instead of an idiot lite with a needle as some on here have described. I think this because at the time when the oil pressure was "bobbling" around. I could make the actual Red Oil lite come on if I turned on all the accesories(Lights, Radio heater etc) and steared the wheel back and forth to lower the engines RPM even more than holding it in park. If this was a glorified idiot light It should have just dropped to L instaed of bobling around just above it. Just my thought.
hi, please to hear no water in the oil. if you are looking at a standard dash it is a light that comes on when the pressure drops below 7 or 8 psi . you may here the hydrolic lifters clatter if the pressure drops off for a while. sender unit may help to see the back of this problem.
a machanical gauge is all ways piece of mind. bokker
When the oil pressure would drop on the needle it would not completely "Flatline". It would dance around up above half but not where it usually sits at 3/4. If I turned on all the current drawing accercories, and turned the steering wheel back and forth to load the engine via the power stearing pump. I could cause the needle to drop even lower approximatly 1/4 above L. It would dance around that point following the engine's RPM's. Also at that point the actual Idiot Light would pop on and would also throw a check engine light. If I stopped moving the steering wheel and turned off all the accerocories, and put it back in park. The Red oil light would go off and the needle guage would return to its normal position about 3/4 the way to H. The Check engine light stayed on. I did not check the code at that time. I changed the oil and ran it for a couple of days. After about 70miles or so the check engine light went out. I guess what I am saying is that how can an glorified idiot light dance around and different levels. Its bianary it ethier on or off. This is why I believe that this guage is an actual guage. This would also explain why there is an actual Red Oile Pressure Light in the left side if the cluster. I appreciate all the info and I hope I am not beating a dead horse.
hi, well i think you may have a good point and i have just taken for granted the switch operates the needle pointer in a general form, display or not. interesting !
i fitted a machanical gauge for piece of mind and having 2 pressure switches fail it left me with know doubt that the oil pressure was correct. bokker.
It does puzzle my puzzler. I purchased a new sending unit and it is huge. It looks like the one I have on my 1970's 302ci. The one on the 4.2 is relatively small and I will have to do some modification to make this one fit. I will probably just T it and run both at the same time.
hi, i have since checked the gauge in the dash against my machanical gauge and it simply does not represent the oil pressure. it was worth a look, bokker. ps good luck with the new sender and let us know how things go.
also, you can put the trip meter in TEST mode and it will give a digital reading of oil pressure that will allow you, at a minimum, see if the digital data, corresponds to your analog gauge data / idiot light.
I read the article and it was interesting but does not answer my question. If it is a glorified idiot light. When the oil pressire drops enough to trigger the actual Red Oil Can Display Light in the upper left side of the panel, the glorified "guage should be reading L(or nothing). But it doesn't. It flucuates along with the engines RPMs somewhere between Low and the middle position. This tends to make me believe its and actual guage. Freakin' confusing
I've got the same problem with my 4.2 v6 in a 1998 E-250. I do not believe my oil pressure gauge is the "idiot gauge" because it too fluctuates with low engine idle speeds. I originally thought the problem was due to my oil pump, so I bought and installed a Melling replacement oil pump. The oil pump also includes a separate replacement spring and installation instructions. Here's the kicker: the spring is housed in the timing cover, so you have to take off the timing cover to replace it. My understanding is that the spring is a pressure relief valve and it can get stuck in the open or parlty open position, causing the lack of oil pressure at low idle when the engine is hot and the oil has thinned.
My original temporary fix has been to give it a little gas when at idle and in drive, but this sometimes causes an error code to be thrown (I think, but am not sure, it's 1506 - something like engine can't control idle speed - because I'm giving it the gas). My other temporary workaround has been to just put it in neutral, which keeps the rpm's high enough for adequate oil pressure.
My van doesn't have a tach, so I can't easily tell the idle speed in drive (the van does not have a digital odometer / tripmeter, so I can't use the digital dash method). I am wondering if I can increase the in gear idle speed so I have decent oil pressure until I can tear apart the engine. With an EFI engine, idle speed must be controlled by the PCM, so I wonder if in gear idle speed is a separate set point or parameter apart from in neutral idle speed. I don't want to change the "nonadjustable" butterfly valve screw because then my neutral idle speed would be excassive, and it might lead to other problems and error codes being thrown. Any thoughts / suggestions until I can do the real engine work? TIA
hi, if the oil pressure relief is stuck try moving the ball against the spring pressure to see if it will seat correctly when it pushes back. the ball can be seen thru a drilling in the mounting face that the oil pump fastens too. my money is still in the sender being faulty. bokker.
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