I have bragged about my 5.4L too much I think. It has 220,000 miles and a lot of mods. It has been used HARD! It is now dropping oil pressure at idle when the oil gets hot. It does have a dail on the dash but no numbers just a good range and at idle it will drop to nothing and the red warning light comes on. I watch for it and don't let it stay there. I just touch the gas pedal and it will return. If I am stopped in slow traffic I hold the brake and give it a little gas.
I know it doesn't need much pressure at idle but I don't know what it is really doing without numbers on the gauge. I have had engines do this before without any problem and as long as you stay on top the gauge they have run for years more.
The question is just how worried should I be about this in this 5.4L and what does it say is in its furture? I was getting ready to change the cams and spend more money on it, but I don't know now? Is there an oil treatment that will help? If I don't do the engine upgrades I planned because it is about to blow up and it runs for two more years like this than I will be pissed off.
Just hook up a mechanical oil pressure gauge and find out where you are at as mentioned above. Then make plans from there. With 220K of hard miles you need to know what she really is doing before you start throwing money at it.
It could be that you need to switch to 10w30 oil, at this point the clearances may be opened up to where the 5wxx isn't filling the gaps anymore. But you really do need to see what's really going on first.
OK I found a gauge around the shop to see what the pressure really is, I only got one problem now. WHERE is the damn sending unit at on this 2001 SD 5.4L??!! If it was a snake I am sure I would be dead by now but I can't find it. I found it on my 2005 F150 5.4L, but they are different. I fell stupid to ask but I can't find it!
OK I found the sending unit now I have a new problem. I have to unplug the wire off the top of the sending unit before I can remove it. With the headers in the way I cannot see it and am operating on fell alone. I don't want to break it and I can't fell how it unsnaps. Any help please?
OK I know what is in my 5.4's future. A slow death! So, I am going to put it out of it's misery.
I used it a lot this past week and it is going down hill fast! It won't hold oil pressure for long at all at idle. Worst, it is knocking HARD out the bottom end. When I have a load of some kind on it the knock will quite up. But when I am just cruising on level ground I can hear the crank and rods slapping hard. It's a goner!!
I always hoped I would send it out in a blaze of glory at 7000 rpm in a mud pit, but I can't bring myself to do it. I am going to DRIVE it to the best engine shop I can find that knows how to build a Triton motor and tell them to give it back to me with 400hp+. Hopefully they can use the block and maybe some more of it and save a little money.
I never even got the pressure guage hooked up. I don't need it to tell me any thing when I can hear it!! It's sounds like a PSD, HA, HA HA!!
it could just be ur oil pump drive rod. same thing happend to my brothers 90 mustang, we could only find like half of it when we took the motor out lol. but same thing as you, at idle almost no oil psi and justy give it gas and it go up.
but hate to say it, it may be to late from the sounds of it