Loud knocking noise

I have a 3.2L DOHC 2001 Isuzu Rodeo with 82,000 miles
I have an extremely loud knocking noise coming from the right side of the engine. I disconnected the spark plug one at a time to see if it was a rod bearing like a repair manual said, however it still knocked constantly. The knock increases as your increase the RPM's.
This is not a soft knock, it is very loud.

Just bought the truck the other day knowing it needed a repair.

Thanks, Brian.

This could be just a weak timing belt tensioner. VERY common problem that many mistake for a rod knock. The hydraulic tensioner pusher gets weak allowing enough slack in the T-belt, that the belt slaps against the black plastic t-belt cover making this noise. Take off the timing belt covers to see if the noise stops. This noise typically stops at higher RPM's since enough oil press gets to tensioner pushrod to tighten the belt @ higher RPM's.
G/luck
Joel

Do you not think this could be a lifter? I will check timing belt tensioner.

Thanks, Brian.

I have knocking sound under idle and and/or around 2500 RPM, what can I do?

Commonly this is caused by the idler tensor that keeps the serpentine belt (the only you can easily see on the engine) thought that is bad – or – the timing belt tensor is bad.

Check both. If you remove the S-belt (the one you can see) run the truck for 30 secs and the noise goes away then it is that tensor.

Do you not think this could be a lifter? I will check timing belt tensioner.

Thanks, Brian.
No. The 1998-2004 3.2/3.5 has no lifters. It a cam right over valve (direct) setup, with adjusting shims. Like Ryan says, check all your belt driven accessories. My bet is this is a timing belt tensioner issue. Hopefully that's all it is!!! :uhoh:
G/luck
Joel