Cm870 compressor

[Kdub870]

Is there any way to get the compressor to stop knocking? I’ve got a 2007 kw w900 with a cummins 870 and all you hear is the compressor constantly knocking. Had an 871 and it never sounded that way.
Also looking at some help with ecm. It’s be demandated but by previous owner. Would like to be tuned right. I’ve sent a pm to unilevers but haven’t received a response

[Chamberpains]

Be patient on the response. PM Mommaburt too. He works with Uni.

As far as the knocking, does it stop once the compressor kicks out? If it does then this is usually just the nature of the beast.

[Signature620]

You can try removing it and timing it to the engine.

Turn the engine over until the "insert pin" mark on the damper lines up with the mark on the lower gear cover.
Remove the compressor and rotate the gear so that the X lines up with the cutout in the housing (3 o'clock position looking from the front). Refit the compressor and see if it's any better.

If it still knocks excessively it might be getting tired in the bottom end. Keep in mind that they usually make a noticeable knock - It might be OK.

[JimT]

When my compressor died on my 2250 I thought the new one would be quieter. Nope, just as bad if not worse, but only when building air.

[Craag]

I just had a new compressor put in cm 870. I've heard no knocking since installed a week ago.

[Pigpen 2869]

Dont worry it will get loud again.

[Rawze]

always ensure it is timed correctly...