York PC 843 Compressor oil pressure problem

[tvrao]

Hi,
Some can help me.
Compressor tripping on oil pressure low alarm after running of some time. its recently overhauled.
bearings, oil pump, valve plates and unloading solenoids are replaced. oil is 5GS, oil screen is in good condition. pressure transmitter is working fine.

suction pr- 80, dis pr-320, oil temp-140, oil pressure at start 40, reduces after some time to 20-25 and compressor trips.
i find oil temp is on higher side(140), could it be a problem? and what could be the other reason for low oil pr

thanks in advance
regards

[tvrao]

hi,
further to the above, i add some more details

when one of the unloading solenoid valve is energized, Oil pressure is maintaining around 40-43. compressor is running continuous however seems partial loading, current is around 54% with one solenoid is unloading.
problem is encountered with all the valves in loading.

[Grizzly]

Hi.
Do a bump test and see if any cylinder discharge Valves are passing.
What Oil level have you in the sight glass?
It sounds as if you have a Cylinder loading gear issue.
140f =60c is high but not at trip level.
when you say the bearings have been replaced, which ones do you mean?
Did you look at the Main bearings?

Grizzly

[tvrao]

Hi mr.Grizzly,
Thanks for writing.
Oil level in the sight glass is visible
Bearings replaced. i.e pump end and motor end main bearings.
the only parts that I didn’t change are correcting rods and pistons.(rings changed)
I didn’t have idea what is this bump test, can you please explain?
Thanks
tvrao

[RANGER1]

tvrao,
I think typo & should be pump test, or basically run compressor, Close compressor suction stop valve, machine shuts down on low suction pressure, close compressor discharge stop valve immediately.
Discharge pressure should not decrease rapidly, but very slowly equalise to suction pressure over at least 5 minute period.
If it equalises very quickly, something leaking internally, like valves& seat, cylinder liner gasket in housing, internal relief valve, if it has one.
Internal leakage causes overheating.
You also need to trace oil circuit & determine where oil could leak if all you bearing clearances were checked & within specifications.
In your case unloaders seem suspect leakage area.
On some compressors a hand oil pump can be connected into oil circuit, pump in oil from drum & see if it comes out in correct, or incorrect places, like missing crankshaft oil gallery plug etc.
Try to simulate

[Screwgle]

Hi tvrao,
Did you manage to fix your problem?
Did you overhaul the compressor yourself?
If I remember correctly there is an oil relief valve which is located on the underneath of the main bearing housing, inside this is a small steel piston & spring, if this is worn this could be the problem?

[tvrao]

Hi,
I couldn't fix the problem completely, however due to compulsions i am managing the show with one of the solenoid valve permanently energized which lead to partial loading. my amb temp is nowadays came down little bit and with partial load, oil pressure is maintained at around 60psi and i haven't checked the oil pressure with full valves in loading again.