I have a strange for lack of a better way to describe it sucking vibrating type noise under a load while accelerating in my 04 2500HD 6.0 liter 4x4. It only does it in second or third gear (auto tranny) while towing a trailer under a load. It sounds like a leak in the intake air system almost like a gap and something is vibrating while the engine is sucking in air under the load. I know it's a poor way to describe it but don't know any other way to do so. Do any of you have an idea of what this might be? I just removed the K&N filter and replaced it with a plain filter and cleaned my MAF sensor I haven't driven it yet to see if that did anything. Any ideas are appreciated!

Thanks

 

Exhaust rattle?? My 8.1 rattles every now and then under load, pipe rubs on top of a exhaust hanger bolt.

 

No not a rattle it's hard to describe but more of a sucking type noise under a load only with a trailer behind you. It doesn't realy do it with just the truck taking off and when you hit high gear it doesn't do it anymore. Sounds almost like a suction through a piece of plastic something that has a crack or leak when it shouldn't, but I find nothing like that when I looked. I was hoping a mechanic might have run across this issue before and know what to look for.