compair road compressor help please

by kirk hardiman
(lincolnshire uk)

>COMPAIR ROAD COMPRESSOR Perkins prima 500 series engine, new head gasket. Starts and runs and revs fine. Cold start speed controller solenoid bypassed due to engine coolant temperature sensor and or wiring fault, but speed control valve pressure checked with no leakdown and operates.

engine will only start with air cock open and must be run for approx 60 seconds with tap open or engine cuts out if cock shut even when warm.

after this time when air cock shut engine revs down to idle as it should and ticks over with 100psi in receiver and no air from safety release suggesting unloader is functioning.

however when air cock opened full bore engine labours to pick up speed for approx 5 seconds before reving. if air cock opened partially engine labours then cuts out. unloader diaphragm has 3 splits approx 1/8" inch long in side wall. would this cause the unloader to open excessively for the air demand/ engine speed causing engine cut out? Would be really grateful of any help


kirk skegness lincolnshire englank uk

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