Hi all,

Didn't trust my stock oil pressure gauge so I set out to install a manual oil pressure gauge today. Installation went quick, BUT I didn't like the results I saw.

At cold idle the oil pressure stays at around 55 psi-at hot idle it's around 15 to 20 psi. The one thing that scared me is that at 2000 rpm cruise I'm only pulling about 25 psi of oil pressure (fully warmed up after 15 or so miles of driving). Should I worry? The engine doesn't make any racket other than a slight valve train noise when warm. You can rev the snot out of the motor when warm and there is absolutely no abnormal noises. This engine only has 76000 miles on it however I really don't know a whole lot about this engines history other than talking to the previous owner who said he changed oil every 4000 miles and drove it to work 10 miles one way 5 days a week for the entire life of the truck. Everyone says I'm worrying too much about it if the engine doesn't make any abnormal noises.

The truck is a 94 and I'm running Mobil 10w30 petroleum based oil with a Motorcraft FL-1a filter.

Someone please respond so I can sleep tonight! Wish I would have never put that stupid gauge on! lol

 

Anybody???

 

I have the factory manual for the 1988 pick up. The specs for oil pressure is

Hot@2000 rpm
40-60 psi


You oil pressure is below spec.
Stop revving the snot of it, it doesnt help!

At this point you have to figure out is it the oil pump or are the bearings worn or both? Or just drive it easy, dont beat it, it may run like this for several 100k without problems.

I would recommend hooking up Snap On tools or any high quality gage to double check the accuarcy (sp?) of the gage you installed

 

No worries. At least not for quite a while. My truck has almost identical oil pressure as yours does with right at 230,000 miles. No noises. My buddies truck has about 25 psi cold and actually shows no oil pressure when hot. It raps pretty hard when first started then has slight rod knock after that. He drives 100 miles a day to work and has for about 4 years. No idea how many miles he has. His speedo quit a few years back. Revving is definately not good with low pressure but low speed lugging can actually be worse. Just watch for a sudden drop in pressure. This would indicate a problem in need of immediate attention. Otherwise keep the oil level where it should be and drive it. You will be absolutely amazed at how long your 300 will last with that kind of oil pressure.

 

before I rebuilt my 300 in my 78 she had 15PSI cold idel about 11psi @2500rpm and 0-1psi at idel hot And other than a slight lift noise it ran fine always started this was about 3/ yrs /4k mile ago and the lifter noise It still has after rebuild so I"m not worried at that was staight 40 wieght Valvoline

 

Thanks for the replys!

I don't rev the truck just for the heck of it (the old 6 never sees above 2100 rpm when I'm behind the wheel, except for expressway driving, which I don't do a whole lot of. Good thing for the Mazda tranny.) I was trying to see if a slight rod knock was present on engine run down-there wasn't. I've also tried to listen for main bearing noises under low rpm and different loading conditions-nothing. This engine doesn't use a drop of oil and keeps the oil very clean between changes. Guess that means it's probably okay.

Just got back from a day long 300 mile "power trip" which included approx. 70 or so miles of high speed (approx 75 mph) expressway driving. Same thing-25 psi oil pressure, and with slightly higher readings at approx 2600 rpm. Pulled into a wayside and took a little listen-no knocks.

 

good luck finding a six with high oil pressure, mins is about 60 cold, then 15 at hot idle. i have 160,xxx hard, hard, miles on mine. I installed a Oil cooler which brought it up about 5lbs at idle and 10lbs highway. I just wanted to install it because of the plowing and offroading i do to make the motor work less.

 

It should be ok. The general rule is as long as you have 10 lb's pressure per each 1000 rpm, you are ok. But that is a sign things are starting to wear a bit. Could be the pump, but most likely the bearings are wearing a bit. My fresh rebuilt 300 does 45-55 all the time. Hot or cold. MK

 

Hi Sheltrow,

Your inline 6 should hit 45 to 55 lb. @ 2000 RPM warm ....
Mine hasn't for a long time, I've got 203000 miles on her now still starts and runs fine a little bearing noise if you use a stethoscope.
I've just got the idiot light in the dash so I bought a oil pressure test gauge from JCW my pressure is about 25 psi a 2000 RPM.
I still drive it daily and would trust it for long trips

1981 F100 Custom Short Box

 

How is your oil level? Also, what viscosity of oil are you running? What about the oil filter? In some engines, if it is clogged, the pressure goes up, but in some it goes down. How long has it been since you did an oil change? Maybe 10w-40 oil would help the drop in pressure when the engine is warm. If that is what you are already running, how about adding a can of STP? Good luck, John

 

Good morning,

I run Mobile 10W-30 petrol based oil with a Motorcraft FL-1A filter. I myself am **** with oil changes changing oil between 1500 and 2000 miles on everything I own, but I'm not so sure that the previous owner was as good-he said that he changed oil every 4000 to 5000 miles. I'm so **** that on this truck (and previous trucks) that I own that I've went ahead and installed an hour meter. When that hour meter reaches 200 hours regardless of the mileage I change the oil. (I use this truck for work and put in many slow or idling hours.) I check oil level on a daily basis.

Food for thought-I went to my buddies repair shop and saw a Chevy truck with a 350 in there, probably a 1998. The man had no oil pressure what so ever, but had ran Lucas in there from day 1. Pulled the pan down and saw probably the grossest thing I've ever seen since I used to work for a septic pumping contractor. The beauty of it is all main bearings plasti-gauged out within spec. The only reason he brought it in was because of the no oil pressure and the lifter clack from hell. Only 43000 miles. What a shame.

 

I would try changing the oil with 10-40 and see if that makes a difference. Good luck, John

 

ever see the test the guy did with lucas oil additives. It actually caused more air in the oil causing a lack of lubricity. I am also **** about my engine oil, don't want to have to repairr too much on my motor. Mine is at the most every 2k. That way i know al the particles in the oil are getting out of the motor.

 

Update!

Brought the truck into the Ford dealer for a very rusty oil pan and a leaking slave cylinder. I told him to (because of somewhat low oil pressure) to replace the oil pump and screen. He said he doubted that was the problem and that he would check the main and rod bearings.

He called up Tuesday morning and said all my bearings rod and main were bad. He said that he didn't even have to plastiguage them. I picked up my truck yesterday and inspected the bearings myself-ouch! Hopefully the new bearings will last as he didn't regrind the crank-he said it wasn't necessary.


My question is this-how can a truck with only 75000 miles ruin the bearings-both main and rod? Its too bad that I don't more about the trucks history the first 70,000 miles or so of its life. The main bearings were wore where the two halves meet and NOT AT ALL in the middle of the halves-the crank journals didn't even touch the middles of the bearings at all! Rod bearings were somewhat better and showed more normal wear patterns, however were still pretty wore. Could this have been a factory mistake by not tourqing the main bearing caps properly?

Oil pressure is much better now and is 35 psi at hot idle and 55 to 60 hot or cold anything above 1000 rpm.

 

Ditto here, 239,000 miles, low oil pressure for 150,000 miles and still running. Now heres how I increased mine when it dropped to below 20 lbs. I put a quart of Motor FLush, idled it like it says on the can, drained the oild replaced filtert and oil. Prssure jumped up to 37 instantly. Running good now.