Clicking Sound from engine

[bterry123]

We returned from a short 600 mile trip today and when I backed the coach into the garage, I noticed a loud, heavy metalic clicking sound coming from the engine. It is a 400 ISL on a 2004 Newmar Mountain Aire with 49,000 miles on the odometer. The sound is similar to the sound of a clicking lifter on a gas engine, but the speed of the click does not increase when revving the engine. You can hear the sound when in neutral at idle, but it is much more noticeable when in gear, forward or backward. I have noticed no loss of power and the engine idles smoothly and performs as always. Any ideas? Thanks in advance.

Bill Terry.

[Bill0828]

bterry123..It's hard to compare engine noises via computer but two years ago my Cummins,ISC330 started making a loud metalic sound with similar symtoms that you describe. Mine turned out to be a bad engine air pump. Sounded like someone was hitting the engine with a small hammer.Thankfully, it was still under warranty. Your best bet is to get it to a "qualified" repair facility. It was a very involved repair after seeing the repair order. Good luck with it.