93 Navajo Oil Pressure

[mezrein]

Hey guys, Ive posted about this in the past, but this time its really concerning me. Attached is a picture of my gauges and you'll notice that my oil pressure is, atleast in my mind, very very low. Engine temp is not really all that high and I have no check engine or check oil dummy light on for what its worth. I changed oil first week in July, standard 5 quarts of 10w-30 non-synth with a K&N filter. I know I have some smallish oil leaks, nothing that leaves a lot of oil on the driveway, just a couple drops here and there. The current picture is of the gauges at idle, but even while driving on the freeway at 65 it was around the same place. I have also swapped out the oil sending unit about a year ago when I posted about this before thinking it may have been bad. The gauge still functions near as I can tell, since I noticed it this morning I watched it while doing a hard acceleration and it went up to almost half way between low and high. Again, engine seems to be running just fine, not getting hot and not really burning oil all that much. Just really concerned about it since Im now driving 380 miles every week as apposed to closer to 150 miles every week.

Thanks!

 

[the_don]

Thats a sign that the bearings and oil pump are starting to get some wear on them. if your really worried about it you can connect a mechanical oil pressure gauge to verify the pressures you can also start running a little heaver oil say a 10w40 and see how the engine tolerates it.

 

[mezrein]

sighs... bearings sound expensive.. How much do oil pumps run? Im hoping that the pump is easily accessible after removing the oil pan?

 

[the_don]

the oil pump itself is not that much about $65-$120 bearings are not that much by them self but in order to replace the pump the engine has to be pulled due to clearance issues between the oil pan and crossmember, an experienced person with a properly stocked tool box can have the engine out, replace the pump, main bearings and rod bearings and back in within a weekend, personal i wouldnt try it on a dd if i had to be at work friday and the folling monday

 

[natenkiki2004]

Everybody's forgetting that the dash gauge is a dummy gauge. Anything over 5PSI and it shows pressure in the dead middle. The ONLY reason it deviates from middle is due to wiring or the gauge itself. Mine will deviate while driving even if RPMs don't change. I've checked my pressure with a real mechanical gauge and it's plenty within spec. If that was a real gauge, it would show high until the engine warmed up then lower at operating temp as the oil thins out.

Even if you did have low oil pressure, it'd be time for an engine overhaul. A new oil pump wouldn't fix it, you'd have to do all new bearings on the connecting rods & mains. At that point, you may as well do a rebuild.

If you truly are concerned, get a mechanical gauge. If you indeed do have low oil pressure, that's a tough call. Higher weight oil may not have enough flow at the top of the engine, then again having low pressure probably won't give you the flow of regular oil either.

Really though, I wouldn't worry about it. Even if the gauge is right, there's nothing short of a rebuild that you can do to truly fix the issue right. Just drive it and use a quality oil.

 

[mezrein]

Really I have to take the engine out to get the oil pan off? Sighs.

 

[mezrein]

Ok everyone keeps mentioning the mechanical gauges. How much are they, and how do I use them? Lol

 

[the_don]

i think i got mine for about $30 from napa. if your just using it for a few then you can remove the pressure sender and connect it there but for a more permanent install the you need to install a "tee" between the pressure sender and the block then connect the gauge there.

 

[mezrein]

Ya my brain already went to a more premenant solution. Trying to figure out how I can mount it inside the car as well.

 

[mezrein]

Also, what is optimal oil pressure for the 4.0?

 

[2stroke]

According to ford, anything over 5psi is just fine. In reality, I like over 15 psi at a hot idle. 5w30 should be fine year round, but even here in MN, oil pressure gets very low during the summers. I run 10w40 in the summer, 5w30 in the winter. That way the oil pressures are the same year round.

 

[natenkiki2004]

My spec book lists 40-60 PSI hot at 2,000 RPM with 5w-30.