oil pump

[bigman1]

Hi,i have had a lot of trouble with the oil pump on my perkins 4107,the oil relief valve stuck open twice,removed it and came o the conclusion that the spring was weak(very old engine)so i made a 3/8"long spacer to increase tension,fitted it to engine hey presto no oil pressure,removed it ,made drive shaft with 1/4"tang to fit slot on pump shaft to drive pump with power drill fitted pump in vice,lots of oil pressure,so now i have pump with oil pressure on bench and none in engine,iam realy pissed off wish i could afford a new engine.Any ideas.Ronnie.

 

[tinkicker0]

adding a spacer alters the preload, it does not alter the spring rating.

 

[gordmac]

It will alter the pressure the valve opens at though. Is the valve seat passing oil? On the competition and road engines I used to build I blocked off the filter bypass valve. How did you measure the pump pressure when you tested it out of the engine?
A pump doesn't in itself generate pressure it generates flow, the pressure comes from the resistance to flow from the pump. If you have flow but no pressure then you have a leak somewhere just after the pump.