I have a '93 4Runner with the 3.slow.

I have a knocking sound in the upper end. The knock is much louder than a tick, its definitely a knock. Sounds like its in the passengers side valve cover.

When the motor is first started, it knocks 2 or 3 times, then stops knocking.
There is no knock at idle. When I rev the engine, the knocks comes back, then is gone when I get close to full throttle.

I'm certain its not a rod bearing. I had a bad rod bearing and replaced them all. This is a different noise and a different location.

I have taken off the throttle body, upper intake plenum, and the valve cover. I don't see anything obvious. ( it kinda sounds like there was something rattling around in the valve cover, but i cant find anything in there ). I checked the resistance on the injectors and they are 13.5 ohms. Tomorrow I am going to measure the valve lash.

Any ideas what it could be? I'm debating on sending the injectors to witchunter and have them cleaned and tested. But i don't wanna spend the money if I don't have to.

Thanks,
Mike

 

I'm not sure how a bad injector would lead to knocking.

But as far as idea on your issue, I would say definitely check your valve clearences. although I believe valve noises wouldn't come and go.

My dad's 1999 chevy 350 van is having similar issue, hugely loud knocks for a couple second at startup, then it runs very well. Also, can't start without a little spray of starter fluid.. weird problem that I have to fix. I wonder if it's same type of problem as yours now.

 

Mine had a slight knock, but it turned out to be a pulley for the timing belt.