Basically, the motor is making a noise that sounds like it's coming from near the top of the motor in either the #2 or #4 cylinders. When the motor is cold, I can't hear a thing. Once the motor starts to warm up, the noise gets progressively louder and then remains the same. The frequency of the noise is direcly related to the RPMs, and doesn't vary with intensity upon decel or anything.

With a timing light hooked up to the #4 cylinder plug wire, the noise and the timing light appeared to be in sequence. I swapped the lifters from side to side, and the noise stayed on the passenger side. I also have readjusted the rockers a few times, and the noise remains the same. I have also tightened the plugs, unplugged the injectors one at a time and replaced the header gasket to try and eliminate all the basic stuff.

From what I've read, a noise like this that is only audible once the motor warms up, is a bad wrist pin. I want to confirm this as much as possible before I pull the motor. Any help is appreciated.

 

Anyone have any experience w/this?

 

I'de put money on the block not being clearanced correctly for the larger throw.

Why don't you pull the pan and view it from below before you go pulling it?

 

My feeling is that it's something internal, so I might as well pull the motor - even if it's not the wrist pin. Also, I'd think if it was a clearance issue with the block that the noise would be there all the time, not just when the motor warms up.

 

Did the noise change at all when you unplugged the injector? If it is a rod knock or pin bore issue, taking the load off the piston from the firing event should have made the noise much quieter. did you pull the valves on that cylinder and check for pulled material indicating that when they heat up they might be sticking?

Disregard that last sentence, I was mentally still on my diesel page....that would not apply to these motors....

 

I'll have to pull the injector again and see if the noise changes.

 

I pulled the #2 and #4 and #6 injectors off one at a time, and the noise doesn't get quieter - it just gets more erratic because the motor is idling rougher.

 

pull all the injectors one at a time.

 

I've pretty much pin-pointed the noise to the #2 or #4 cylinder. I guess it wouldn't hurt to pull the rest of the injectors to see if the noise is coming from somewhere else.

 

I unplugged the rest of the injectors on the passenger's side one at a time and the noise never changed. I'm not sure what else to try.

 

Ya can't hear a rod knock at idle unless it's fixxin to window the block.
A wrist pin ya can. A pin can be heard at decell too.

 

Thanks for the reply. Any other ideas to try to diagnose this noise?

 

Not without pulling it apart.