Unusual noise ?

Oh-one · 08-21-2011, 03:47 PM

I noticed a new noise coming from the engine compartment on our 07 Holiday Rambler with a Cummins ISL 400hp with 30k miles. The noise is a high pitch whistleing that starts when the engine is started and persist for several seconds after the engine is turned off. I can hear it clearly but cannot tell where the source is located. I suspect the turbo and question: does the turbo continue to spin after the engine is stopped? If it is the turbo, what do I need to do? If it is not the turbo what is the source of the noise? Thanks Sam

wa8yxm · 08-21-2011, 04:26 PM

Yes the turbo can continue to spin.

You have either a vacuum or a pressure leak would be my first guess.

But the turbo can continue to spin.

Drifter · 08-21-2011, 05:04 PM

There is a turbo By-pass hose that sometimes leaks. It looks about a 1 inch dia. with a 90 deg. bend and about 5" long. You well most likely lose some turbo boost when it's bad. It's easy to change when the engine is cold.

LewF · 08-25-2011, 02:01 PM

Is this something new. Cummins engines whine or whistle as a normal sound. The pitch changes with RPM but it can be clearly heard if you have your window open and are driving slowly through a campground as an example. You can also tell the big rigs that have Cummins engines on the road by the whistle they make - it comes from the turbo charger. Sorry if this is something you already know. We had an 07 Endeavor 400ISL and it whistled and now we have a Camelot with a 425ISL - same sound.

Oh-one · 08-31-2011, 06:30 PM

The noise is new. It continues after the engine has stopped for about 30 seconds. I am taking the MH to Power South Jacksonville, a Cummins sevice center. I will post later when we find out what is causing the noise. Thanks for your replies.