Rattle/Buzz/Grind at 1900-2000 rpms
 

I've discovered a rattley/buzz/grind noise that happens when accelerating or decelerating past about 1950 rpms. It almost sounds like someone sticking something in a fan blade. You can replicate the sound in park. If you hover at that rpm, the sound is constant, but it goes away as soon as you go above or below that rpm. It sort of sounds as though its coming from the front passenger side of the truck, but its difficult to tell. I haven't been able to localize it any further, just due to the fact the engine is so loud anyway at that RPM. I didn't hear it when I was test driving it, but that could have been because I was just distracted by the mass amounts of tire noise.

Any ideas on what the culprit could be? Thanks

Check your skid plates and UCP. make sure they aren't bent or loose. Sometimes the skids or UCP will get slightly bent and vibrate against the exhaust pipe. Also if the skid plate/s are missing a fastener or have a loose one you can get the same type noise.

I agree, I might not know much about the H1 yet but I've worked with lots of equipment and vibration issues. This sounds like at a certain rpm causes a harmonic that causes a loose part on the vehicle to vibrate, the vibration is like a sine wave and at that rpm the amplitude of the wave starts to match up and vibration increases, as soon as the rpm changes the amplitude of the wave is offset and in a sense cancels out so the loose part doesn't shake.

Lots of Jiberish, but true.

Hope you find it that would drive me crazy since highway speeds the rpm is around 1950 rpm.

Cheers

Forsche

Oh ya, if its while you are driving it could be a u joint in the drive train, If it is while you are driving and stopped I think it would be with the exhaust system and shrouding around it.

I may not be any help but I love to talk about the H1, just got mine love it, love working on it, love starring at it, mine has a few small issues as well.

Cheers

Rattle found! A broken weld around some of the shrouding along the exhaust. And yes, 1950 rpms translates to 55mph, was very annoying! Thanks for the tips.

Awesome, "I love it when a plan comes together".