Here is a good one; Yesterday I started my truck and I could have sworn what i heard from under the hood right after fire up was what would be described as when you have a missing spark plug, or one not tight... if you could image that sound..

It was not all that loud but i heard it for a moment.. Weird; never heard that before.. thought i did but did not think much of it..

is it possible to have a leak in the head that is closing right after a few seconds of running?

Just trying to get some ideas.

 

Not the head maybe but how about your exhaust manifolds/gaskets? It's pretty common to be noisy when cold and seal up as they get hot.

 

Perhaps.. might be a good excuse to put some nice shorty headers on it and the aftermarket Y pipe.. :X..

 

It did it again.. almost like sprocket is not retracting on the starter; I'm going to have my self a look at it.. its right at startup.. I think its coming from the worm gear on the starter..

Let you know!