Well, I'm now in the 100K club. For the past couple of months (or more) I've noticed my valves chattering when the truck's in a lug. Down shift and it's fine. Can my valves be adjusted? 03, 4.6 by the way

 

I have the same problem in my 99 4.6. I was just searching about it believe it or not. I read that they need adjusted but how would you do that?

 

Sounds more like detonation to me... I don't know that I have ever heard valve "rattle". If there is enough slop in your valve train for them to "rattle" then I would guess you need to re-work the entire heads.

Just my $.02...

 

There is no adjustment to the valves, as they are hydraulic.

 

probably detonation

 

What could be the cause of this detonation then? It idles around 600 rpms and if I hit the throttle really quick then it will dip down (with that quick rattle) then go back up. It does it with higher octane fuel as well.

Any ideas?

 

My truck rattles too. Oh wait...

 

Lose the throttle body spacer and put the stock intake back on it.

To the OP - try higher octane fuel.

 

When the trucks in a pull, say up the mountain at low RPM's...detonation???? It sounds like an old Chebby with cheap gas...well, not that bad....and that was the valves.

I have always heard this to be "floating the valves"

 

yea with my old engine, it would detonate at low rpm going up a hill. if he is floating the valves at idle... i cant imagine how it runs above 1000rpm......

 

He said it would do it if he rev'd it up...mine will too. I can let it set for a minute or two at idle, blip the throttle and get a slight chatter. It won't do it again if I blip the T right after. Almost like it loads up.

 

like a bleeding lash adjuster

 

CDB03STX - That is a perfect description of what mine does. Also going up hills it will do it if i blip the throtte. But not all the time tho. It needs great tho. Could this detonation be due to bad gas or not high enough octane? Could my intake cause this condition being that is does have a tune?

Built - It runs great over 1000 rpms. Seems like I have a clutch that Im lettin it out too soon.

 

bleeding lash adjuster???? What is it?

 

Yes to both.