driving 300 around with no oil pressure.

[MintFord]

I picked up the '90 F150 thats in my signature pretty cheap a few weeks ago. I was suspicious of the oil pressure gauge because it never dropped out of the normal range with the engine off, but being my impulsive self I had to have it I think someone moved the needle. It didn't make any odd noises. I put a mechanical gauge on it and it had 30psi cold and 0psi hot at idle, about 5-10psi hot at 2000rpm and up. I cut the bottom cover open on the oil pickup screen and cleaned all debris from it, put in new main and rod bearings and an oil pump this weekend with only a 10psi cold improvement, no better hot. The journals looked good. The only noise it makes is some very light lifter noise after it warms up. It runs quite well. I assume the only thing left that can be bleeding off the oil pressure is worn cam bearings, or maybe an internal crack somewhere in the block casting. I found a local truck junkyard that has a few non-smoking good oil pressure 100,000 mile + 300s complete from oil pan to throttle body for $400 to $550 with 30 day warranty. Thats the direction im leaning. I've been driving the truck full throttle everywhere I go this week (over 200 miles) and it doesnt get any worse. My two questions are, What would you guys do if you were in my shoes? and strictly out of curiosity, What's likely to happen to this engine if I continue to run it? I'm guessing maybe the cam will lock up, or bend a pushrod when a lifter collapses? I'd like to run it to death and see, but don't really want to be stranded somewhere. One customer at work said he had a 300 drop oil pressure at 300k miles and he ran it up to 400k before it blew up.

[srercrcr]

I'd try another mechanical guage.

[MintFord]

I forgot to mention that after hooking up the first gage, I tried another mechanical gage along with a different tube that reported the same sad news I also tried blowing compressed air into the sending unit port hoping there was a blockage. I'm extra pissed off because I specifically searched for a 300I6 truck because of their amazing longevity. I sold a 170k mile 2wd 300I6 F150 that ran like it was brand new and had a constant 50 psi of oil pressure, to buy this piece of crap. If it weren't for the fear of it quitting out in the woods while offroading, I'd be happy to drive it to death. If its still running when I buy a replacement motor, I'm going to hold it to the floor until it "pops" (I'll try to make a video)

[Grogtronics]

Did you replace the oil pump with a high flow oil pump? The high flow pump will compensate for the worn out journals in the engine and still get the oil to the nessasary parts in the engine.
My oil pressure was about 30 before I replaced the pump and the main and rod bearings but afterwards it was back up to 60psi. the high flow pump drops right in without any modifications.

[85e150six4mtod]

If the lifters aren't complaining and the mains aren't starving, and there is oil up top, I'd guess it would run a looonnngg time. No sense blowing it up though. Cam won't lock, but the lifters will clatter real bad then you might sieze a rod and window the block. I'm more into fixing than blowing up these days....

[MintFord]

Thanks for the advice. I used a stock oil pump since i put in new main and rod bearings. Since it made it through this week of abuse, I guess I'll run it a while under more typical, more gentle driving conditions. It'll be a testament to the durability of the 300 to drive it with no oil pressure for the forseeable future. I doubt most other engines would hold up at 0psi for more than a few minutes. I'll update periodically on how she holds up in this experiment. I would enjoy rebuilding it, if machine work wasn't so expensive. I paid $500 just for the machine work on my 302.

[Ford_Six]

A possible source of low oil pressure is the oil gallery plug behind the timing gears. If this little allen head pipe plug is left out, the lifter oil passage just dumps out onto the timing gears.

[80broncoman]

Originally Posted by Ford_Six

A possible source of low oil pressure is the oil gallery plug behind the timing gears. If this little allen head pipe plug is left out, the lifter oil passage just dumps out onto the timing gears.

Very true and the oil will run right back in the pan.

[johnboy427]

I had a 360 that always read 0 at idle but still held about true to the 10psi per 1000rpms rule and it never gave me any trouble. Change the oil out for some thing thicker I run Rotella 15w-40 diesle oil in my 300 and see if that helps at all I have never owned a 300 that really liked 10w-30.
-Johnboy

[OldMetal]

This is just a thought but I would try to fix the engine instead of seeing how long it would go, at this point it probably is rebuildable.

[MintFord]

I have the remainder of the rebuild kit that I bought to get the bearings and oil pump. I suppose I could just remove the cam to inspect the cam bearings and check the oil gallery plug behind the timing gears. If the cam bearings look bad I could pull the motor, have the cam bearings replaced and install the new cam, lifters and timing gears.

[4x4 Bart]

Save money, run thicker oil, try a good brand of 40 weight and a bottle of Lucus. Then check your idle pressure, if you have 5 lbs. your good.

[80broncoman]

After you remove the timing cover just yank the distubtor out and run the oil pump with a drill and look to see if you have any oil at the front.

[Pelican]

Remember, the oil pump really only creates oil flow. The true PRESSURE forms when that flow is forced through restrictions in the oil passages. Like another member said, try running a heavier oil and see if things improve. Even if the pressure doesn't rise, the heavier oil will at least cling to the components better and somewhat help the situation. Or, swap out for a high flow oil pump, which should allow the engine to build more pressure. If THAT doesn't work, I'd start where another member mentioned; Inspect the oil gallery plugs and make sure it's not just dumping back into the pan.