Exhaust manifold leaks can sound like an engine knock. I’ve had this on 2 or 3 V8’s I’ve had over the years (non-LR). In both (all) cases tightening up the manifold to head bolts solved the “knock “.

 

I feel like I am making progress, only it’s in the diagnosis stage and not the remedy stage.

Finally managed to get a few videos that I will try to attach here.



The misfire/clanking seems to be related to the SAI timing. If I keep the RPMs high after a cold start, and wait for the engine to warm up and the SAI circuit to shut down, no clanking.

Every time I start the engine from cold, and the SAI kicks in, I get clanking and misfires.

If I drive the truck, shut it off, and get back in while it’s still warm, no clanking. So, it seems like it definitely has something to do with the SAI circuit.

I didn’t see a lot of info on how to test this other than to replace parts. But they are pretty $$$. Does this seem like an electric issue or vac leak issue?

getting closer! Thanks guys.

Ryan

 

Did you try this?

 

I just tried the SAI test this morning.

1. I disconnected the solenoid wiring and started the engine.
2. once the RPMs dropped a bit, the clanking is still present, but dramatically reduced.
3. when I reconnect the solenoid, there doesn’t seem to be much of a change. I am not sure how long that SAI circuit stays open, however.
4. when warm, the engine runs perfectly and actually even sounds good for a 2004.
5. I also noticed that when the engine knocks, the tensioning pulley takes a bit of a jump. Not sure if that helps, but figured I’d report back. It confirms my feeling that it is timing related and not something mechanical that tightens up when warm.

Other than the vac lines, everything on that SAI side of things is pretty $$$. Is there a better way to diagnose the individual components before my wallet suffers?

Thanks!

Ryan

 

I wouldn' be driving that until I found the problem! That sounds like a mechanical clank to me.... Get a stethascope from harbor freight and poke it around all over and see if you can pin point an area. If your belt tensioner is bouncing/reacting at the same time then you need to check the rotating assembly up front. Something is about to give in a bad way if you ask me.

 

I should have listened to the video earlier. Sounds like you have a damaged flex plate. Have you checked the engine oil pressure?

 

Sounds like a torque converter to me - ask how I know