[68c10airstream]

A friend had a similar tick in his 5.3 2001 suburban. As a past dealer mechanic i used a wooden stick to my ear to figure which valve cover to remove. It would only tick warm, so once warmed up, off came the valve cover and with a feeler gauge of say .020" go from one valve tip and to the next with it running and when you get the feeler gauge to go in between the valve and rocker tip and quiet the tick down, that's the lifter or valve with issue. In the case of my friend's 5.3 i installed 1 lifter and all was good. If your motor is varnished up a lot a trick i learned from the 70's with sticking piston rings from varnish in chevy chevettes is to add a quart of naptha on top of a full crankcase and run it for a day or two at slower speeds and drain it out. You can do it as many times as you wish.

One word of caution is keep an ear to the engine when you drive it with the "naptha" in the engine, as in a severe case of varnish letting loose it may plug up an oil filter.I'm not saying your engine is real dirty inside, just some info for anyone reading this.

I have at least 4 "naptha" stories, 3 of which i was involved in with great success!