I know this is a very old story with the 2.9 but I thought when I overhauled the engine, I would have cured it...but... itttsss baaaack !

When I first start the engine, it clacks it's butt off, when it warms up, just sitting there idling the lifter tap goes away completely But, if I drive it down the highway at freeway speeds it will come back pretty bad at times with three or four lifters acting up and other times only one is tapping. If I let it sit and idle a few minutes the tapping/clatter will go away, like magic.

The worst thing is when the lifters start clattering, it's only a couple of them that get bad enough to affect valve operation and cause low power and miss situation.. again, if I come to idle speed for five to ten minutes... it quits and runs smooth again... If I put a few ounces of sea foam in it while it's tapping.. it immediately quits tapping and runs smooth.. but then that only lasts till the next time I run it down the highway... what gives?

Engine had all mains, rods and cam bearings replaced less than 5000 miles ago..along with new oil pump, timing chain and sprockets, lifters and heads and gaskets... engine had a cracked head..reason for overhaul... It didnt do it at all for about the first 1500 miles...I really dont want to pull the heads AGAIN.

Someone told me that part of my power loss issue might be the fact that if enough antifreeze went through the cat converter when it was being driven with a cracked head, to screw up the cat, partially plugging it... the longer and harder I drive it.. the quieter the exhaust noise gets...weird huh?
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