I was towing my boat through the mountains yesterday and I had the truck in Tow Haul mode. The boat and trailer are around 3k dry, so it isn't that heavy of a load (maybe 3,500 with fuel and gear). Anyway, it seemed to be making some very strange knocking noises right before it shifted. It didn't do it all the time, but there were times where you could hear a normal rattle/knocking sound, then all of a sudden, 3 or so very, very loud knocks right before it shifted.

I took it out of T/H mode and it ran perfect. Any idea what it could be? It was loud enough that I was worried, especially since those roads have very few places to turn out, so breaking down up there is not a fun thought...

Thanks all,
-Jeff

RPm related, sounds like pilot injection to me. Sounds like someone inside the motor with a sledge hammer working their way out. Do a search on pilot injection and you will get a better description.

I have a 2006lbz and i have never heard pilot injection like my 2003 lb7:confused: does it still use pilot injection ?

Ahh yes i have noticed the same problem
this all started a couple nights ago after i stopped at the truckstop for seom diesel

it only rattles in TH mode to come to think of it
and it only happens every now and then when ur crusin at a steady speed and then go to accelerate


dont know i was worried to but it still runs great??????
:help: :wtf1: