Sump pressure

I was busy putting the upper and lower sump back on my engine last night and was wondering is the sump is under the same pressure as the rest of the engine or is a small percentage of the engines oil pressure or even has non with it being really an oil collection bowl.

Seems the oil is getting sucked from the sump via the oil pick up and the oil drain hole/return hole is so big i would have thought the pressure would be minimal.

Any views or information on this guys and girls.

you get crankcase pressure, i'd imagine it'd just be the same as the pressure you get when you remove the oil cap with it running. So yes, same as the rest of the engine I'd imagine.

There is no oil pressure in the sump but there will be gas pressure, caused by ring blowby and vented by the PCV system.

so what sort of gas pressure can be produced within the sump.

In theory there should be negative pressure when the engine is running due to the PCV valve, if its working correctly.

I have measured for pressure using a reasonably sensitive gauge attached to the dip stick aperture, and the result was no positive pressure recorded.

I will also point out that this was with uprated UK twins, running 1.2 bar,on a sound engine, never got around to trying it with my single.

without sounding stupid what is the pcv valve and where is it located.

PCV is Positive Crankcase Ventilation. It's a whole "system" like the oil system, cooling system, etc etc.. There is a valve or two in the system and these can bung up, causing problems.

Everything you could want to know about PCV is here:

http://www.mkivsupra.net/vbb/showthread.php?t=46158

-Ian

Positive crankcase ventilation valve, and its located in the right hand cam cover,and is attached by a hose to the plenum, it functions this way.

When the engine is running and under light load/cruse (off boost) there is a vacuum created in the plenum, this sucks any oil vapour and blow by [gas etc] from the combustion process into the intake and is burnt,

Once the engine is on boost there is a flap valve inside the PCV valve and this then shuts under the positive pressure so nothing enteres the engine.

Once there is positive boost the ventilation is taken care of by the vent in the other (left hand) breather in the corresponding cam cover, which is vented into the turbo intake which on boost is also under vacuum.

This is without the added complication of the evap system;)

cheers guys much appreciated.