1996 Nissan Truck engine rattle

IF the valves are in need of adjustment, you should hear them all the time, regardless of RPM's. In this case, it is really hard for me to diagnose the problem without hearing it. Either you can upload a video to youtube so I can hear it, or I would recommend allowing a mechanic with a trained ear listen to it.

Let me know,

Please venture a guess!! On another front, yesterday the left front started sounding like I had a beer can stuck on the tire as I drove! There was no beer can. the noise stops when I hit the brakes. I jacked the truck up and spun the wheel, a slight ticking sound is what I heard. When I wiggled the wheel up and down there was just a tiny bit of play. Wheel bearing or something with the brake?

As far as the new noise, since the sound stops when you use the brakes, I would say they are the problem. That is where I would start looking. With a wheel bearing, the sound will change when making turns. However, it is usually a growling sound that is heard.

As for the motor noise, I hate to guess and scare you if I'm wrong. However, based on your description, it sounds like a rod bearing or a cam bearing. Is it more of a knocking sound?

I'll check the brakes, thanks! The motor noise isn't a knocking sound at all. It sounds like something under the hood is loose and rattles like marbles in a tin can. Thought I had found the problem when I discovered that the heat shroud over the exhaust manifold was very loose, tightened it up but that made no difference. I've wiggled and poked at everything else and the only other thing found is the end cap for the cat converter is free floating up and down the exhaust pipe and probably contributing to the sound but that's far away from the apparent source of the sound. Is there any chance that at higher rpms the top end of the engine could be getting oil starved due to nasty oil build up and would it help to have the crankcase flushed?

If you tap on the converter and muffler, do you hear a rattle from inside? The insides can come loose and cause that kind of a noise.

Let me know.

Banged on converter and muffler, no rattles. Thinking maybe higher rpm oil flow problem. would a flush at my local oil change place be worth a try?

I wish I could hear the noise. It would make things much easier. Have you allowed a mechanic to hear it? Sometimes all it takes is a trained ear. As far as the flush, it won't hurt anything, but it may be expensive to do and I don't know if it will help. If you think the oil pressure may be a problem, you should rent a mechanical gauge from the local parts store and check to see how much pressure is actually being produced.