LOW...L0w...low oil pressure

[diezelcrazee]

This is on my 89 f250. I noticed my idiot gauge would go to zip and the check engine light come on at any rpm under 1000. So I put my Autometer check gauge in the sending unit oil galley on the back of the block. 1000 rpm reads 2 lbs , 1500 rpm is 8 lbs, 2000 rpm is 15 lbs and 2500 rpm is 20 lbs.

The truck isn't rattling or knocking (yet). I know about the oil pressure regulator in the filter/cooler head. Anyone ever seen that stick open, which I think would allow most of the volume/pressure from the pump to bypass???

I guess the other option is oil pump and bearings...

Any ideas are welcome! Thanks

 

[Devon Harley]

Check oil level our oil pumps usually don't go out

 

[smokinpipes]

I assume your autometer check gauge is a mechanical unit? If so, I would check the bypass valve (as you stated) for something lodged into it, or a weak feeling spring... all else, mains or pump. Though as stout as the oil pumps are, I've never seen one give up the ghost.
Dumb question, oil level okay? Been changed recently?

A test to see if the internals are tight, change the oil and filter and put two gallons in, and see if the pressure increases, if not dump in a two or three quarts of Lucas and see if that helps. If it does, something is loose, if not... well....
You could take the approach of my father.. "Ahh Effit... Just run it; when it breaks you'll know what was wrong" ... THOUGH...This apple fell far..FAR from the tree

If the gauge is electric, replace the electronic senor. Cheapest, easiest fix and see what happens then.

 

[diezelcrazee]

My check gauge is a mechanical, have it threaded directly into the oil galley. It is full of oil according to the dipstick, I had thought about changing the oil/filter, but its not really thin and runny like diesel would be. I would think it would be obvious if that were the problem, and the oil on the stick looks like the viscosity is about right.

I guess its hard for me to think pump and bearings, seems like if that was the problem it would have more than 2 lbs at idle.

Thanks

 

[smokinpipes]

I suppose it could also be a plugged oil pickup screen? I'm just throwing ideas out there because I agree with you; it's an odd one indeed.
Does the oil pressure rise quickly to the lower pressures? Or does it slowly climb to them after some time has passed?

 

[Devon Harley]

Maybe the filter is bad and plugged or fell apart inside i've heard of that but not expierenced it before.

 

[rhkcommander]

have you tried any oil cleaning products? changed oil types?

I've heard you can clog up the passages with gunk if you suddenly switch over to synthetic or use a cleaner.

 

[NO_SPRK]

is there a external oil pressure regulator... sorry i have no idea how the oiling system works in these engines

 

[Dave 001]

If so, I would check the bypass valve (as you stated) for something lodged into it.

x2......pull the oil cooler assembly, disassemble it, and have a look. FYI the pressure regulator assembly is staked in and "not serviceable" according to IHC. But it is still visible and you'll be able to see if it's stuck open or not.

Just to ease our minds, test your Autometer gauge with your (or a buddy's) air compressor. It's not impossible that the sending unit is bad as well as the mechanical gauge. My brother-in-law (working on a dirt driveway, the closet auto parts store 30 miles away) pulled the oil pan on his Toyato car to replace the oil pump, inspect the screen, etc. Turns out the only thing bad was the sending unit!!

Dave

 

[Dave 001]

Maybe the filter is bad and plugged .....

Even a 100% plugged oil filter will not cause his problem.....that's what the oil filter by-pass valve is for.

Dave

 

[diezelcrazee]

I suppose it could also be a plugged oil pickup screen? I'm just throwing ideas out there because I agree with you; it's an odd one indeed.
Does the oil pressure rise quickly to the lower pressures? Or does it slowly climb to them after some time has passed?

I hadn't thought about the pump screen, good call on that. Pressure rises right along with the rpm, no delay.

Maybe the filter is bad and plugged or fell apart inside i've heard of that but not expierenced it before.

Thats a thought, but they have a filter bypass in the filter head, is supposed to open if the filter plugs. Guess it could be stuck as well.

have you tried any oil cleaning products? changed oil types?

I've heard you can clog up the passages with gunk if you suddenly switch over to synthetic or use a cleaner.

Havent done any of that, I just bought the truck about 3 months ago, havent changed the oil. Been fixing stuff ever since, first it was the IP shaft seals, then the speedo drive gears, then I noticed the rearend leaking (havent fixed that yet), then I noticed the oil pressure.....

x2......pull the oil cooler assembly, disassemble it, and have a look. FYI the pressure regulator assembly is staked in and "not serviceable" according to IHC. But it is still visible and you'll be able to see if it's stuck open or not.

Just to ease our minds, test your Autometer gauge with your (or a buddy's) air compressor. It's not impossible that the sending unit is bad as well as the mechanical gauge. My brother-in-law (working on a dirt driveway, the closet auto parts store 30 miles away) pulled the oil pan on his Toyato car to replace the oil pump, inspect the screen, etc. Turns out the only thing bad was the sending unit!!

I have another gauge, I'll try it as well. I'm a firm believer in making sure before u go and fix stuff that aint broke! If my gauge checks out, looks like I might be pulliing the oil cooler...

Thanks agian

 

[racer30]

If your oil pressure is low and dynamic to engine rpm you probably have a stuck open pressure regulator. Once your regulator "sticks open" you won't have enuff pressure to wash the debree out. You need to pull your oil cooler off and look in the regulator for a chunk of silicone or something blocking the valve from closing. Drop the coolant and oil. I have heard that jacking up the engine and removing the engine mount can give you more room to get the cooler out. but I havent had to do this in a truck. I R&Red one on a buss chassis one time but there is no side mount on a industrial application. Good luck

 

[jaluhn83]

The oil pressure gauge tap on these is at the far end of the oil system, so 2 psi there doesn't mean necessarily that the bearings are starved. It's not good, but I wouldn't say you're sol yet.

Oil flow on the IDI is through the pump at the front of the motor, then out through the oil cooler fore to aft. The aft header (the one the filter threads onto) has a pressure relief valve and a filter bypass valve internally. From there it goes to the main bearing galley and to vertical passages that connect to the lifter galleys and up to the oil pressure fitting.

 

[diezelcrazee]

x2......pull the oil cooler assembly, disassemble it, and have a look. FYI the pressure regulator assembly is staked in and "not serviceable" according to IHC. But it is still visible and you'll be able to see if it's stuck open or not.

Just to ease our minds, test your Autometer gauge with your (or a buddy's) air compressor. It's not impossible that the sending unit is bad as well as the mechanical gauge. My brother-in-law (working on a dirt driveway, the closet auto parts store 30 miles away) pulled the oil pan on his Toyato car to replace the oil pump, inspect the screen, etc. Turns out the only thing bad was the sending unit!!

Dave

I changed out my test gauge and hooked up a new out of the box mechanical one, and the best I can get out of it is 25 psi at 2500 rpm, 2 - 4 lbs at idle.

If your oil pressure is low and dynamic to engine rpm you probably have a stuck open pressure regulator. Once your regulator "sticks open" you won't have enuff pressure to wash the debree out. You need to pull your oil cooler off and look in the regulator for a chunk of silicone or something blocking the valve from closing. Drop the coolant and oil. I have heard that jacking up the engine and removing the engine mount can give you more room to get the cooler out. but I havent had to do this in a truck. I R&Red one on a buss chassis one time but there is no side mount on a industrial application. Good luck

Ok, I took the oil filter off and I can see the regulator valve. I think it is stuck open, but not sure from this view what position it is supposed to be in. Should any of the hole in the valve be visable? I gently pried on it and I can't move it any to the left (as seen it the pic). I can move it a little to the right, but not far enough for the steel ring to touch the right side. It just seems to me that the steel ring should be against the housing on the left. Does anyone know from looking at this pic if it is stuck partially open? Anyone doing an oil change and could take a look at the position of your valve..... Sorry for the not so great cell phone pic...

Also, the filter bypass disc and spring (not shown in pic) are gone. From what I have read that shouldn't affect oil pressure, but it would allow oil to bypass the filter, correct?

Thanks alot for all the replies and help, much appreciated!!

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[Dave 001]

Also, the filter bypass disc and spring (not shown in pic) are gone. From what I have read that shouldn't affect oil pressure, but it would allow oil to bypass the filter, correct?

I may miss-understand you your comment so bear with me.......There is no by-pass valve or spring in an IDI oil filter. The oil filter by-pass is located in the oil cooler header.

I have a 7.3 apart at home.....I'll look at the oil filter mount when I get home and report back.

Dave