Engine dies at 5 bar

[fluxcored]

Hi all,

Got a petrol engine driven compressor for free. The unit is close to 30 years old. I've plugged all the leaks and replaced the oil in pump and engine.It is quite small but adequate for my modest needs.

It has got a CDI Genie Mark II unloader valve with a safety valve.

Problem is the engine runs fine but at 4 bar it starts to struggle. Close to 5 bar it dies. I can coach it to 6 bar if I play with the throttle. At those pressure levels I'm unable to get the engine to start again and have to release some air. At below 4 bar the engine will fire up again.

I'm unable to properly identify the engine which makes it even more frustrating.

Any hints will really be helpfull.

 

[bawjaws]

possibly that the engines piston rings have word down with the amount of use its had over the years which equals to low engine compression = low power, so check for that

 

[fluxcored]

Thanx, did'nt consider that option - will investigate.

Appreciate your reply.

 

[dinkystu]

Fluxcored have you got a non return valve between the compressor and receiver? I had the same problem with an electric motor blowing fuses...fitted n/r valve =problem solved HTH Stu

 

[fluxcored]

Dinky, I think it's built into the unloader valve - http://www.cdivalve.com/products/continuous/continuous.htm

I think you've just given me food for thought - the non-return/check valve restricts air flow only in one direction so that the engine/motor operates less stressfully. From what I can google.

Does this mean that no pressure will exist between the unloader and the pump?

If true and if my check valve is shot then my system will behave as it currently does - essentially you being correct.

 

[dinkystu]

From looking at the website it has a built in n/r or check vave which as you rightly say allows the motor to work less stressfully the unloader should release the pressure in the discharge line from the pump allowing esay start up. It sounds like the unloader or check valve are not operating correctly leaving pressure in the line from the pump thereby stopping the engine turning over. That would also explain why if you release air pressure it starts. Stu

 

[fluxcored]

I'll look into it.

Ta, Stu

 

[fluxcored]

The load Genie Mk II (Part # LGM20) is two valves in one viz a pilot unloader valve and a NRV.



The engine should only be started when there is no air in the tank or when the lockout facility is engaged on the valve ie the pull ring is held up by the spacer bush. This ensures that the air vents to atmosphere when the engine starts thus a no load situation.



Normally the petrol engine would be started when there is no air in your tank. When the pressure reaches the set blow off the valve will divert the air from going through the outlet into the tank to going through vent port. The engine will then idle under no load as the air is not being compressed, just blowing off to atmosphere



When the pressure drops to the cut in (approx 15% below cut out) the valve will reintroduce air back into the tank, thus putting load onto the engine again. This cycle will continue without switching off the engine until air is no longer needed whereby the engine is stopped.

This is what I received from Control Devoice Instruments representatives re the Genie MkII.
So well it seems that the hard start is'nt due to the valve being faulty.