Cummins air compressor knock

[speedmerchant]

Just curious if any of you guys notice a slight knocking sound from the air compressor when it is engaged and charging the system? Spoke to a Cummins shop and they say that they have seen lots like that and that just seems to be the norm with the Cummins. Anyway mine is going in next week to have it checked and tested etc while it's still under warranty. It could be the "norm" but an air compressor is basically the same as an engine (or vice versa) and to me shouldn't knock. Anyway I'll keep you all posted. For reference I have a 2008 360QS with the 340 Cummins that I purchased about 3 months ago.
It's not a overly loud sound but definately noticeable when standing at the rear of the coach when it's charging.

James

[speedmerchant]

The shop is replacing the air compressor as they said it was starting to make more sound than should be acceptable.

[Lynkage]

Was it a Bendix pump? 2 stage 2 cylinder?

Glad they are fixing it for you.

[speedmerchant]

Not sure but I thought these engines used a Wabco. I can find out.

[speedmerchant]

Originally Posted by Lynkage

Was it a Bendix pump? 2 stage 2 cylinder?

Glad they are fixing it for you.

Single stage, single cylinder, Wabco

[Lynkage]

Thanks speed.

I ask because even my old 1979 International 2200 with a cummins 290 had a Bendix 2 cyclinder 2 stage and it was a fairly easy rebuild (about a day) and was curious as to what they use now days.

Glad they are fixing it.

Happy thanksgiving!!

[speedmerchant]

So, new compressor installed and.......still makes the same sound. So it would appear that the one Cummins shop I spoke with was right. They seem to make some clatter on this set up for some reason. Could be the sound of the pulses magnified through the steel air line to the dryer but in any case there doesn't seem to be reason for panic if any of you should notice the same sound I heard. Cummins was gracious enough to cover it under warranty as a precaution, so many thanks to them. In fact I have to say that the service I have recieved from Cummins has been excellent. Any phone conversation or information exchange back and forth has been second to none. And also for Forest River has been excellent with anything from questions to technical help regarding the coach itself. In having only onwned this coach for 4 months now, I feel secure knowing that these two companies that make up our coaches (and Freightliner, but they are a no brianer for a great chassis), not only make a great product but back it up as well.

[VinceU]

Originally Posted by speedmerchant

So, back it up as well.

Wondering, could it be a noisey check vave down stream? I know piston style can clop with each discharge stroke, flapper style will bang, etc.

[speedmerchant]

Originally Posted by VinceU

Wondering, could it be a noisey check vave down stream? I know piston style can clop with each discharge stroke, flapper style will bang, etc.

could be Vince, I'll look into it closer......in the spring. Put the coach to bed this weekend.