please any advice would be appreciated. I’m lost with my H2. Just had engine replacement and have this horrible grinding rattle as soon I accelerate. It’s much worse the steeper the gradient. If I continue to accelerate the engine/gearbox temp starts to climb and the noise is extreme. Also did this with old motor which tells me it’s something else. I’ve attached a video of the noise it makes. While stopped and accelerating there’s little to no noise, only when under load.

 

Transfer case maybe?

 

Almost sounds like detonation and the fact it only does it under load is suspicious and you say the engine temp, goes up kinda supports that. Did you just do a regular rebuild on your original LQ4?

 

I bought a used motor with 40,000 miles on it to swap over. It runs perfectly at idle now and on all flat roads. As soon as there’s a steeper gradient this will start Happening. It has Magnus supercharger fitted to it if this makes a difference. This was rebuilt when engine was fitted.
I’m getting no codes now which makes the situation harder.

 

I still vote for detonation because of the load and now you mentioned the supercharger that even makes my detonation thought more viable. One thing you can do it run premium fuel plus add some octane booster. If the noise goes away you have your answer...