so when driving i hear this chattering/tapping sound sometimes from my engine compartment. i dont hear it idling tho. it comes and goes when it pleases and sometimes is quiet but other times it is really loud. i first thought it was an exhaust leak but i replaced the downpipe gasket and still the noise is there...any insight as to what the problem could be? maybe the speedo cable because when its really cold it makes some god awful noises...thanks for the help guys!

 

Speedo cable only turns when the truck is moving.Sounds like a valve shim,pull the valve covers and check the valve clearance.

 

right, i only hear the sound when the truck is moving.. also the engine is a remanufactured from oregon engine rebuilders with about 8k miles on it. any other thoughts to what it might be before i start digging?

 

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so you hear the noise when the truck is running meaning you are driving it while hearing the noise? does the noise sound like its coming from right behind the dash? hahah and does it do away with a good smackin on the dash? sorry for the questions but i hear the same sound in the mornings on the way to school. It comes from right behind the dash and goes away when i smack on it. I figured it was my speedo cable because i do notice my speed jump around a little bit while its making the noise.

 

yeah it only makes the noise when i'm driving. i'm almost positive its comming from the engine bay... you know those distant sort of sounds...next time it does it i'll smack the dash and see what happens

 

think we are talking about different things here then. The noise I hear is really loud and sounds like its right infront of you.

 

yeah i hear that from the speedo cable when it gets around 30ish here...

 

Does it almost sound like a loose washer rattling? Kinda what my chatter currently sounds like, but I can't find the reason.

 

maybe..but the washer would have to be making enough noise to ruin a conversation in the cab...

 

You could have an exhaust leak between the exhaust manifold and the block? I had an exhaust leak in that location and it was only heard under heavy acceleration. My manifold was warped and a new one fixed the problem. You can check for this when the engine is still cold by feeling for exhaust leaking around the edges of the manifold.

 

I might no be right, but I had the same problem, and tutned out to be a bad valve. It also could be a fuel injector you are hearing