Oil pressure drop

[X-North]

I have a oil pressure drop suddenly sometimes when you look on the gauge it point on the M of normal and suddenly it go to the O. after a couple gas pedal press it go back to the M and stay there for a lot of miles and go back to the O again. It have only 3000 kms oil change is it possible that the cheap Fram cph8 filter do that or thats something else???

thank you for your advices

 

[awood]

You'll find more info than you'll ever want to know about the oil pressure indicaton system by doing a search on this forum. The short answer is, when it goes to zero...and if your engine still sounds normal, that suggests that your pressure is actually still okay. You will likely have a bad oil sender. There's other issues with the gauge and/or resistor in the circuit, but those are somewhat rare. To simplify things, just throw a sender unit at it. If you still have a problem, then check the wiring. The sender unit should be directly below the power steering pump.

There's a metal "stand-off" that the sender mounts to. It goes between the sender and the engine block. It might be a good idea to clean it out, as there's likely some oil sludge in it.

 

[awood]

I just re-read your posting. It looks like it doesn't drop to zero, but rather it drops to the O in the word "normal" on the gauge. The sender is nothing but a switch...on or off. If the needle fluctuates, there's a resistance fault in the circuit somewhere, likely the sender unit itself.

 

[X-North]

ok guy. to clarify more ...the sender unit is new. the metal part between the block and the oil sender i took it out because it was so rusted so i put the sensor directly on the block. it began 2 days ago the oil drop but still ok. i will look at wiring diagram and probably rebuilt the wiring from the dash to the sensor. i use a Fram cph8 oil filter and 15W40 oil....the oil have now 3500 kms ...maybe thats becuse the 15w40 become thicker of the fram filter become clogged at some places...dont know...so i bought a new oil filter and will only change it remains the oil in the enine to see if the pressure will be better. if thats the problem i will change the oil company filter.

 

[awood]

Going off my memory here...all the sender (switch) does is supplly a ground at about 7 psi oil pressure. That's not very much! When the ground is made, a full 12 volts would be applied to the gauge and it would read full scale, except along the way there's a 20 ohm resistor that provides a voltage drop. This brings the needle on the gauge down to some mid-range value that would look something like a normal pressure reading. I've had my instrument cluster off (for other problems) and I've seen that resistor soldered on the back of the cluster.

Try this...just unplug the wire going to the sender and jumper it to a good ground, anywhere on the engine. If you have a normal indication, then you have a faulty sender, even though it's new. If not, you have a resistance fault in the circuit somewhere. If you had an actual pressure problem, then the pressure would have to be hovering right at 7psi, which I would think would be VERY unlikely. To make absolutely sure, you'd have to purchase and install a direct reading pressure gauge.

All this, of course, assumes that there's been no modifications to the circuit!!!

 

[Maniak]

Here is a good thread about the oil pressure gauge on the 1st gens explorers..

http://www.explorerforum.com/forums/showthread.php?t=14894&highlight="fake+oil"

In short...
Stock, the gauge only has two readings.. Normal and no oil pressure.. Anything in between is just electrical changes (battery voltage, dirty ground etc).. The gauge shows normal at anything above 7psi.

~Mark

 

[X-North]

thank you guys!!!!! I changed my oil filter only without changing the oil because it had still 2000kms to do and the pressure goes to the M of normal again. For my part the diagnosis is....Fram sucks!!!!!

 

[mikeinri]

I'm not here to defend Fram, but I've used plenty of them over the years, and have over 275,000 miles with no issues.

Not sure that this would cause a pressure problem, but why are you using 15W40? I use 5W30 (which is recommended by the manual), again, never had a problem.

I just hope you don't have a real problem somewhere that's being overlooked.

Mike

 

[X-North]

I am using 15W40 because i have to do long roads...i use thicker oil that will not shear under higher eat...like all industrial fleet do.

 

[quicklook2]

fram filters do not work well on fords, most of the time, always exceptions.

that oil seems a little thick for an explorer.

 

[X-North]

i will change for "Giganto" napa/wix gold filter and high mileage 10W30

 

[ezeedee]

fram is ftl. i wouldnt use one if i got a truckload for free.

and holy thick oil batman! 15w40? i still run 5w30 in my explorer, whats your reasoning for running so thick?

 

[X-North]

Like i said earlier posts...i do a lot of roads and uphills so i use the same oil as industrial fleet Shell Rotella 15W40

 

[X-North]

How much voltage do you get from the oil pressure wire when you ground it to the battery? and if you plug it with a jumper directly to the battery will it stay in the middle on NORMAL or it will go absolutly to the right?