I'm hoping someone can help me identify this strange noise. It is coming from the passenger side of the engine toward the back. It's the background clicking noise that your can hear in the video. Because it is inconsistent, I don't think it is coming from the rod bearings, valves, etc. I do have a misfire in cylinder 3 but I think that is from a bad coil pack. I'm going to change that next. The engine also does not run rough like you would expect if it was from a consistent misfire.

 

I forgot to mention that it is a 4.6L engine with SAI. I'm starting to think it may have something to do with the SAI pump or valves.

 

That can often be a vacuum leak... Check all the SAI hoses and the two valves.

 

I'll start with the hoses tomorrow and then the valves. I also noticed that the SAI pump bracket is broken so the previous owner may have had problems with it. I only paid $500 for it (2004 SE, 112,000 miles) so I don't mind buying a few vacuum hoses.

 

$500! That's a nice looking truck!

 

That's a steal for $500 if it isn't rusted to hell.

Can't see your video, but a fast paced clicking can be the SAI solenoid, located on the side of intake manifold drivers side toward the back.

If it is SAI related, don't let it scare you. SAI system parts are relatively cheap these days and easy to swap. I just revamped my entire system for like $150 recently. Pump, valves, solenoid, and replaced metal piping with rubber hose behind the intake manifold.

 

You stole that truck! Could be a a spark arcing to ground - probably on cylinder number 3. Open the hood at night with the engine running and you may see it. Check the plug wires carefully for burns, cracks.

 

It's an Idaho vehicle (no salt) so there was not a spot of rust on it except for the hydraulic step in the back. I found a nearly new one for $5 in the pick and pull. The frame looks like it just came from the factory.

 

Thanks for the tip, I will check tonight. I did pull off the fuse box in the engine bay and push down on all of the relays and fuses and the sound has mostly gone away.