high air pressure - @ 150 psi

jaycocamprs wrote:
The Compressor on a diesel engine is always turning.

To my knowledge diesel air compressors do not pump all the time, most are equipped with a bypass device of some sort. When 120 psi is reaached the regulator forces the compressor into bypass mode until air pressure is required again. If the regulator/bypass is inoperative than the compressor will continue to produce pressure. When the air pressure reaches the blow off point around 150psi +- a safety valve will lift off to prevent high pressure damage. That probably is the air that is being purged continuously. This would also account for readings of 150psi.

Regulator components fail more often than compressors, and can be replaced easily.

most are easy to adjust with a screw on the back of the regulater

The Compressor on a diesel engine is always turning. As We Cant Wait said the air governor is bad. My guess is the labor to replace will be more than the cost of a new one.

I agree with ChooChooMan. If your compressed air system is blowing off frequently, it's probable that the compressor is running continuously. In addition to the pressure relief switch, which controls the blow-off, there's another one that should shut the compressor off when the correct reservoir pressure is reached.

It's very likely that switch has failed closed.

I am just going by what our locomotives do, since I do not own a DP. I have the syste, check as the pressure switch that turns the compressor on and off may be bad and making the compressor run all the time.

If in fact you are running 150psi, then you need to have the air governor adjusted down to around 120 psi. The Air Governor is normally mounted right above the air compressor and is easy to adj if you have basic mechanical ability. Google search air governor to get a pic of what it looks like and how to adj. it.

IF it is purging at 150 psi. that is the psi the safety valve is set at. IF you want lower psi. You would need to get a safety valve that is set to the psi you want. It pops off when it hits the set pressure