Hi guys,
A little help please. Went to Advance Auto tonight to get some trans fluid. Came out and started the truck up no problem. Check gauge light went on. I look over and the fear of god went through me!! No oil pressure on gauge. I idled the truck home(less than a quarter mile) and shut her off. Seemed to run fine though. If I wasnt getting any oil pressure as the gauge was showing, wouldnt the truck not run at all because the injectors wouldnt fire? I am hopping it might be a sensor(EOP), but I dont want to spend the 35 bucks if its something else. Any help appreciated.
As Robin pointed out, it most likely will be a sensor or gauge problem.
There are certain times when a LPOP is failing or becoming weak, and can provide enough oil to run the engine and supply the HPOP. At the same time, the HPOP is pulling so much oil, that the rest of the engine is suffering from lower than normal lube oil pressure. It's rare that it happens, but it's possible. Usually happens more often with a weaker LPOP and running a very strong aftermarket HPOP setup, since those use more oil than a stock HPOP would. There have been instances where people have made WOT runs with a weak LPOP and aftermarket HPOP, and have seen engine lube oil pressure drop to nearly zero!
Basically, you'll need to verify the oil pressure sensor and gauge is working. If those are in fact good, then you have an LPOP problem. Engine lube oil pressure has to drop pretty low in order for that dash gauge to drop (assuming the gauge and sensor are working properly). That dash gauge is almost like a dummy gauge, since it has such a wide "normal" range.
__________________
Curtis
2002 F-250 PSD
Best time: 15.3 @ 86.8 MPH at Bandimere - 9/10/08
I'd say you're safe. No oil pressure means the injectors won't fire in almost all conditions. For those oddball situations we have Curtis. Now if you will excuse my hijack.
Quote:
Originally Posted by Pocket
There are certain times when a LPOP is failing or becoming weak, and can provide enough oil to run the engine and supply the HPOP. At the same time, the HPOP is pulling so much oil, that the rest of the engine is suffering from lower than normal lube oil pressure. It's rare that it happens, but it's possible. Usually happens more often with a weaker LPOP and running a very strong aftermarket HPOP setup, since those use more oil than a stock HPOP would. There have been instances where people have made WOT runs with a weak LPOP and aftermarket HPOP, and have seen engine lube oil pressure drop to nearly zero!
I can see how this would be possible, but it seems like the stars would have to be aligned just right for that to happen, since just a hair more demand ICP would result in noticeable power drop off.
This sounds more like an improper upgrade (not addressing an improved LPOP) than anything else. Have you seen a consistent line of mods that esulted in this situation? At what point is the upgraded LPOP something that should be included?
I can see how this would be possible, but it seems like the stars would have to be aligned just right for that to happen, since just a hair more demand ICP would result in noticeable power drop off.
This sounds more like an improper upgrade (not addressing an improved LPOP) than anything else. Have you seen a consistent line of mods that esulted in this situation? At what point is the upgraded LPOP something that should be included?
No you are correct, it's rare, and things would have to be just right to have this happen (stars in alignment, fingers and eyes crossed, stick out the tongue, turn 3 times, clap your heels together, and say "there's no place like home").
Because it's rare, it doesn't consistently happen with any particular mod. The only thing that can be seen on a more regular occasion is a slight drop in oil pressure with really big aftermarket HPOP oil systems. On my truck with twin pumps, I'm willing to bet that I can get engine lube oil pressure to drop slightly on a WOT run. However, my dash gauge won't budge, so it's not dropping enough to raise any alarms or concern (at least for me).
If the LPOP is bad, and it's pumping just barely enough oil to keep up, a majority of that oil will be sucked up to the HPOP reservoir simply because it's the path of least resistance. Whatever is remaining will go to engine lube oil, which would account for the drop in lube oil pressure, yet still have the engine running.
But, it is a very rare occasion, and the LPOP has to be pushing out just the right amount of oil to make that happen. Enough to keep the HPOP happy, but not so little that the engine stalls. For the OP, first thing is to check sensors and gauge, and make sure they are accurate.
And I probably dropped the hammer too soon by mentioning that as a possibility earlier. Easy stuff needs to be ruled out first.
__________________
Curtis
2002 F-250 PSD
Best time: 15.3 @ 86.8 MPH at Bandimere - 9/10/08
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