Well the '94 GMC Jimmy I picked up in Fla. developed a noise in the engine (4.3L V6 CPI). It sounds like a rod knock only when I bring the engine up to about 2000 rpm's and it comes and goes. But the weird thing is that the noise is definitely coming from under the intake manifold not the bottom end. Does anyone here know if there is a common problem with these engines that cause this noise. We are speculating maybe a balance shaft or cam and lifter problem. Just looking for ideas before we go tearing into it.

Thanks,

Sarge

Rod knocks and cam noises are two distinctly different sounds, due to the rotational speed differences. A balance shaft, however, can make a noise that could be attributed to either.
Does a 4.3 have a balance shaft? (Not big on the newer V-sixers! )

If that engine has roller rockers, and it might, it can make that kind of noise with worn cam lobe and gaulded lifter rollers.

how many miles on it sarge?  i have one in ellicottville (good motor) if you need to go that route

Yup, there is a balance shaft in this engine. And I believe it has roller lifters in it.

And if the engine is junk "clifton," I will be giving you a call. There is a little over 87,000 on the clock.

Sometime later this week or the beginning of next, I will tear in to the top end and hopefully find something obviously wrong.

Thanks for the input so far.

Sarge