Another Sabroe SMC112 oil pressure problem

[Neville]

Hi, im having a problem with a smc112 on start up has good oil presure 4.5bar, on loading this presure drops to about 3bar (Dif) and slowly drops until it trips the Oil Presure safety, have changed oil and checked that oil not running hot.
Can anyone shed a bit of light on the matter

[Grizzly]

Have you tried adjusting the oil pressure regulating valve, if so does this do anything?
Just guessing at this stage and wondering if the ball bearing has picked up some crud on it's seat?
I assume at this stage you have yet to check the mechanicals?
There are lots of differing options as mentioned by the guys above.

I had one recently where the oil filter canister had rotated enough for the strainer element to be half in and half out of the oil.
Resulting in fluctuating oil pressures particularly upon loading.
Cheers Grizzly

[Josip]

Hi, Neville :)


Hi, im having a problem with a smc112 on start up has good oil presure 4.5bar, on loading this presure drops to about 3bar (Dif) and slowly drops until it trips the Oil Presure safety, have changed oil and checked that oil not running hot.
Can anyone shed a bit of light on the matter

There are more on RE forums about similar problem as yours. Please try to search for SMC, oil pressure etc...

You did not give too much info regarding ... oil filters, running hours-years;) .... general info about compressor Mk? ... we have to guess all about and this will take too much time and sometimes leading in the wrong direction ... maybe you can update your description ....

Best regards, Josip :)

[Neville]

Thanks for the response, I have opened the crankcase and checked oil filter canister as well as removed the presure relief valve and stripped and cleaned it and adjusted the oil presure relief valve it did pick up the presure a bit. The compressor is a MK1 will have to get back to you about the running hours, I do suspect the loader solinoids could be bypassing to the return to the crankcase or the loader assembly leaking or there could be just too much clearence on the crank gernals, anyone had problems with the unloader three way solinoid valves bypassing?

[Grizzly]

I have in the past had the situation were the wear on the crankshaft journals had reached the point where.
The oil back pressure through the bearings was sufficient to maintain oil pressure until the comp started to load and then the oil pressure just failed.
So you are correct you could indeed have excessive wear.
Cheers Grizzly

[RANGER1]

Neville,
Assuming oil in crankcase is not foaming you could also have a weak/worn oil pump as well.

If loader solenoids are leaking compressor may not load up propery, but of course possible.
Pump should be able to handle it though as if all solenoids energized/unloaded , which is normal on start up.