I have a 03 D2 4.6l engine outside the VIN Range with 98k. The past few days, when I start up the oil pressure light stays on past the self diagnostic time. It goes out after about 30 seconds or so. There are no engine noises or taps. It does not come back on at any point after startup, during idle, acceleration or slowdown. Recently changed the oil with 5W30 Pennzoil synthetic blend.

Any ideas?

Thanks in advance of the wise advise.

 

What viscosity oil had you been using before changing over to that lightweight blend?

 

The synthetic is not a good choice for these engines. You need a good diesel oil with a higher zddp content. Rotella is the primary choice around here. They also tend to like a heavier weight than recommended. I personally mix (50/50) Rotella 5w40 and 15w40 which gives me a good 10w40 synthetic blend. Also gives me enough zinc and sits me in the oil weight sweet spot.

It's also possible you're starting to have oil pump issues. The VIN range doesn't matter; they all suffered. If it's never been replaced then I would recommend you replace it as well as the timing chain. If that's a bad oil pump it needs to be changed ASAP before it scores the front cover, if it hasn't already. If it has even lightly then you'll also need to replace the front cover.

Alternative options are excessive slop in main and rod bearings, walked cam bearings, and clogged oil pickup tubes. That said you'll have to drop the oil pan to repair any of those and by that point you might as well replace the oil pump anyway. Dropping the pan is the hardest part IMO. If you need it, I've got a really detailed write up that you can find in the link in my signature.

 

Your oil is too thin. Go back to something thicker.

The Rotella mentioned above is a good suggestion, though I don't mix mine...

 

What he said... and do you have a 'mechanical' oil pressure gauge to monitor oil pressure? It is one of the must have's when it comes to the 4.6 liter. This aftermarket mod in addition to an Ultra Gauge or other type to monitor water temperature give you a better idea of when you are entering the danger zone. The dummy lights are 'almost' too late and could cost you big money.

 

Before he gets worried to death I'd take a step back & do the easy stuff first. First thing I'd investigate is the oil pressure switch itself. I can't count how many vehicles I've owned that had an oil light stay on longer at startup or randomly flash. Each time it was from an old leaking externally (thru the sensor itself), partitally clogged, or completely INOP/clogged sensor.

My 99 started to have an oil leak that was pretty severe, but hard to locate, then the oil light would stay on longer at startup (with no tapping). Inspected the oil pressure sensor and bingo leaking externally. 99-00's will have D1 type oil pressure sensors. 01-04 have a different style.

Replaced it & good to go! I'd use Rotella 15/40, larger oil filter, and inspect your oil pressure sensor before diving into the engine.

One easy way to tell wth is going on is by listening to your engine at startup. Is it ticking/knocking when the light is on & does the sound change when the light goes out? If it does then yes you have a pressure issue, if not it's probably the sensor itself.