Oil pressure goes down when engine warms up... 2010 diesel

[bingles]

My last post was not correct bad information oil pressure is same at front and rear of block.
Here is what is happening, after engine warms up (not hot just warmed up) the oil pressure drops to about 15psi at really low idle and 20psi at faster idle at about 2000 rpm's it goes back up to 30psi.
When engine is cold I get 38 to 40 psi front and back of the motor.

I understand that the oil gets thinner due to heat but is the correct.
additional information:
I have 3 used oil pumps I checked the gear spacing to oil pump wall sides and top, it was within spec. I did not check between the gears. The regulator has the best of the three oil pump springs, best plunger piston, and 6 washer behind the spring.

I am not an engine expert so I need to know if this is normal behavior.
Thanks for your time.
Brian

[CHA011]

Only stating my expeirenence and often to busy for dialouge. I had three engines apart and here goes. Since you have the oil pan off, measure #1 rod bearing, you will find it worn about .008.. Put it back together for now, remove the valve cover and inspect the CORK end plugs in both ends of the valve rockershaft. You will find them gone, I replaced mine with metal plug with O rings..
Recheck oil pressure, I speculate you will be find, moderate use for awhile. The complete fix is engine rebuild with .010 over size rod bearings, the worst is #1 rod coming thur the block called a window you do not need.. with luck jerry

[bingles]

here is what I know about the engine it was rebuilt, I checked main and rod bearing they was brand new, I didn't measure but crank journals looked great. I didint take rocker arm asym apart, probably gonna have to check that.
I am thinking of adding a new washer on oil pump. All gaskets and pistons are new as well. I did adjust valves to spec.
not looking forward to pulling valve cover better safe then sorry I guess.
every thing I checked on this motor looked good or new so I pretty much left head alone, I was able to spy through head and see head gasket was brand new. Oh one thing I noticed they made a mistake on was no vave seals on intake.

[JD440ICD2006]

What type of oil are you using?
Oil getting thiner when it is warm is not correct IF you are using a multi weight.
For instance, the 15w-40 that I use in my JD 730D is 15 weight when cold, but thickens to around 40 weight at operating temp. The magic of science and polymers but it is true.
Good luck, could be as simple as the type of oil or as complex as a failing oil pump, worn crank bearings, etc.

[bingles]

I assumed oil still got thiner when warm thanks tip.
I was running 15 40 just filled it sunday.
I think I am going to just add washer to the oil pump pressure reg. Since all bearing in the short block are new. When pull oil pan I will measure the crank journal make sure they put right size bearings. If washer doesn't fix it and bearings are right size I will check head rocker arm asym. Should have replaced all that anyways.

[bingles]

I assumed oil still got thiner when warm thanks tip.
I was running 15 40 just filled it sunday.
I think I am going to just add washer to the oil pump pressure reg. Since all bearing in the short block are new. When pull oil pan I will measure the crank journal make sure they put right size bearings. If washer doesn't fix it and bearings are right size I will check head rocker arm asym. Should have replaced all that anyways.

[mnwoody]

Cam bearings and worn camshaft can also reduce oil pressure.

[bingles]

I don't understand why it's so high when cold and only drops to 15psi after warmed up that's at a real low idle, it goes up to exceptable range when rpm is increased. My tach doesn't work so I don't know what rpm I am for sure, but when I say low idle it's just a little above dying.
I am still thinking it's an oil pump issue.

[bingles]

excuse my stupidty for a second...
here is a thought, since metal expands when heated if it was bad bearing wouldn't pressure be less when the steal was cold then when hot. Also got to remember all new bearings and journals looked flawless.
I have all the parts to rebuild rocker asym seems like most likely suspect besides oil pump.

but I will surely check everything while oil pan is off, I won't be able to check cam bearing, but they was new.

[JD440ICD2006]

Other things to check. Plug in a calibrated oil pressure gauge to see if readings are similar. Many oil pressure gauges are not accurate, even though the needle moves up and down with engine speed. If it is a mechanica l gauge with oil line, make sure the line is not bent or crimped anywhere. If it is electric, a loose wire can make some crazy readings.
I suggest never running any engine slower than what the designed idle speed is.

[440 iron popper]

Just a tought. What gauge did you use to make a diagnostic on that? The gauge on the machine or a calibrated gauge. I test a lot of genset engines on load in a year. When I'm in doubt about any pressure, I use a calibrated engine pressure kit and of often the gauge on the machine is inaccurate. That was also the case for my second 440.

[JD440ICD2006]

440 iron pooper,

"great minds think alike" LOL

[440 iron popper]

440 iron pooper,

"great minds think alike" LOL

Hehehe jd440icd2006, A kind of keyboard speed contest!!

If the internal components of the engine show no wear and are on the specs, Why the oil pressure would drop? I learned flying a bit with a cessna 172 airplane couples of years ago... No gauges are really trustable! That eliminated, go to the mechanic side of it. Lack of oil shows quickly on bearings usually.

[440 iron popper]

double post...

[bingles]

I Have a dash mech gauge mounted to front of block and a brand new hand held mech gauge attached to rear of block behind injection pump. Both track eachother exactly. Same readings on both.