2012 IH 7400 4x4 differential chatter while pumping

[CCCFire09]

Took delivery of a 2012 international 7400 4x4 this past week and heard some chatter from the rear differential while pumping. The dealer said this is normal, and it only happens when 'dead heading' or at low flow. I really am not buying this. When we pump this rig the transfer case is in neutral, btw.

Anyone else had this problem?

[npfd801]

Took delivery of a 2012 international 7400 4x4 this past week and heard some chatter from the rear differential while pumping. The dealer said this is normal, and it only happens when 'dead heading' or at low flow. I really am not buying this. When we pump this rig the transfer case is in neutral, btw.

Anyone else had this problem?

Yep. It isn't the diff, my bet is its the PTO driveline running the pump. Even if you had a conventional split shaft pump, the differential should have nothing to do with the pump operating. My engine has this problem, and I hate it. Entirely too many u-joints from the PTO port on the transmission to the pump, and when the pump is at idle or at very little "load," it sounds like its going to come apart.

I could be reading you wrong, but I bet that the transmission is in neutral, not the transfer case. And I'll also bet you can pump and roll.

May I ask who built the rig? I have an idea, but I'm keeping an open mind at this point.

***EDIT*** My assumption is pretty far off isn't it! I found what I assume to be photos of the rig from one of your other threads. The pump isn't where I thought, and looks to me to be split-shaft driven. Still don't think you should be hearing chatter, in my opinion. I assume the pump and roll comes from the auxiliary Darley unit? So you pump in gear, but have to put the transfer case in neutral? Serves me right for trying to act like I know what I'm talking about.

Because I like to eat crow, take a look:

http://www.drakescrossingfire.com/446.html

[CCCFire09]

Boise Mobile Equipment. There is not a tranny pto pump- we have an aux engine pump and a mid mount-rear panel for the structure. We guessed the sound was coming from the rear differential after listening to the source.

This happened while pumping the structure pump. we pump with the transfer case in neutral and the tranny in drive.

[donethat]

Boise Mobile Equipment. There is not a tranny pto pump- we have an aux engine pump and a mid mount-rear panel for the structure. We guessed the sound was coming from the rear differential after listening to the source.

This happened while pumping the structure pump. we pump with the transfer case in neutral and the tranny in drive.

With today’s 4 cycle diesel engines, it is not un-common to have some gear chatter noise in the water pump gear box when the pump is operating with the engine at idle and no load or lightly loaded water pump. The 4 cycle engine power pulses can set up a harmonic with the gears in the pump gear box. The couple of times we have run into this, it was cured by bumping up the engine idle speed by around 50-100 rpm. From 600 rpm to 650 or 700 rpm. Changed the harmonics in the system.

[CCCFire09]

I hope so. It would suck to have an actual problem.