How much oil pressure will a motor run on?

[skeeter_29m]

I have a 1992 2.9. It has plenty of power. It don't use any oil. It don't smoke,but it does tick in the heads like my others in the past. My factory gauge runs on the M in Normal until I drive it harrd for 30-40 miles and when I stop it flickers and drops to nothing. But if I barely give it gas it comes back tho M. I put a gauge on it that shows psi and it starts out running down the road @2500 RPMs 25 psi and as it heats up to operating temp it drops to 5psi. I run 20W50 Castrol with one qt. of Lucas. How long will it run? I have been driving it 90 miles round trip to work and it runs fine. It don't make sense how it could run so good. Thanks

 

[Big Jim M]

That is near the minimum pressure. I wouldn't put it in a bind where it was using all the skinny pedal and not gaining speed...I'd shift gears and allow it to run free'r.
When under a strain the rod bearings squeeze out their oil first causing rod bearing failure.
I'd also set the stop on the TB so it would idle just a bit faster and not drop off it's pressure.
Big JIm

 

[IMenriched]

That is near the minimum pressure. I wouldn't put it in a bind where it was using all the skinny pedal and not gaining speed...I'd shift gears and allow it to run free'r.
When under a strain the rod bearings squeeze out their oil first causing rod bearing failure.
I'd also set the stop on the TB so it would idle just a bit faster and not drop off it's pressure.
Big JIm

Agreed^ +1
5psi of oil pressure isn't very much....once oil pressure drops below 7-10psi..usually spells a short life for the internals of a engine.

 

[BeaterMan]

yea the spec on oil psi is 20psi at idle and 55 @ 2000rpm, so i would say thats way too low. to me, it sounds like something in your bottom end( ie. main/rod bearings) are getting or have excessive clearance due to the fact that when ya rev it up the oil psi goes up. That engine is not destined for long with that problem. id be a lil weary driving that 90 miles a day.

 

[robertc1024]

Man - I'd think about using a lower oil weight. Between the 20W-50 and the Lucas, that stuff's like Kayro Syrup. according to my manual, I'm supposed to be using 10-W30.

 

[chazzone]

Yeah, the heavy wt oil AND Lucas sludge is simply eating your engine at start up.

Ford recommends that the Cologne motors run 5W-30 in all temps, and 10W-30 at extremely high temps.

I use 5W-40 Rotella, might be a good option to try and see if your pressure comes back up.

 

[Big Jim M]

Yeah BUT!

Yeah, the heavy wt oil AND Lucas sludge is simply eating your engine at start up.

Ford recommends that the Cologne motors run 5W-30 in all temps, and 10W-30 at extremely high temps.

I use 5W-40 Rotella, might be a good option to try and see if your pressure comes back up.

Ford specs don't include extreemly WORN engines.. That 50W he's running is barely able to keep up pressure.. Going to a thinner oil will wipe oput his bearings..
Big JIm

 

[piotrsko]

series of comments:

have you run a mechanical gage on it to see WHAT exactly the oil pressure is?

can the oil pressure gage read anything AFTER the engine stops , and for how long? Ie dump the clutch at idle but don't turn off the key. hard to do in an auto tranny.

How many miles on the engine? what does the inside of the exhaust pipe look/feel like? are the plugs nice and clean or gooey on the electrode?

I'm thinking bad sender, no or low coolant, 20-50 ought not be too thick, but I've been wrong before.

If the bearings were that bad, it should smoke all the time.

 

[chazzone]

Ford specs don't include extreemly WORN engines.. That 50W he's running is barely able to keep up pressure.. Going to a thinner oil will wipe oput his bearings..
Big JIm

It's the 20W that's the problem, along with that Lucas crap.

5W-40 is not all that much different in viscosity than 20W-50 once it reaches operating temp, but while it is warming up, he is eating his moving parts alive.

If he has to have a 50wt to get any pressure, the motor is toast already, but there are 5W-50's available that would be a better option.

 

[BeaterMan]

If the bearings were that bad, it should smoke all the time.

as long as the motor has no blow by and the rings are somewhat good, it wont smoke even with bad lower end bearings. it mite start knocking real bad here soon tho.

-skeeter_29m you could try and put regular oil in it but that will more than likely be the end or near the final stand of you engine. If it were me, i'd start looking for a good replacement

 

[RangerJ]

I have a 1989 4x4 Ranger 2.9 auto. I had the same problem with mine. I had the oil pump and bearings and a crankshaft kit etc. Mine is doing real well now.Hope this helps