5.7 L bad valves/lifters?

my 1997 Chevy Pickup with 350 cid and 110,000 miles taps/ knocks when cold( goes away after a minute or two) and when under hard acceleration. A dose
of valvemedic helped the situation for a week or so and then returned. The engine does not burn a drop of oil and still runs like the day I bought it new. Oil pressure is not a problem cold or hot, running >40PSI all the time. Is this a valve/lifter problem or some other sign of catastrophic failure?
Thanks for your help
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My 97 does the same thing, it started around 105000 miles and it has 145000 now, I changed all the bearings and timing chain and it didn't help at all, a mechanic told me it was piston skirt slap and said it won't hurt anything, so I just keep driving it.
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Thanks, John

"Reck" < snipped-for-privacy@verizon.net> wrote in message
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A friend of mine just had a similar problem. It was the Cam. Had to be replaced. $3K.
: my 1997 Chevy Pickup with 350 cid and 110,000 miles taps/ knocks when cold( : goes away after a minute or two) and when under hard acceleration. A dose : of valvemedic helped the situation for a week or so and then returned. : The engine does not burn a drop of oil and still runs like the day I : bought it new. Oil pressure is not a problem cold or hot, running

: all the time. Is this a valve/lifter problem or some other sign of : catastrophic failure? : : Thanks for your help :
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HOLY COW... lets see..
Drain & remove oil pan, drain radiator & remove. Remove Valve covers & loosen rocker arms, remove pushrods. Remove water pump & timing chain cover. Take three bolts out of the cam sprocket, and remove timing chain. Three long bolts as a handle, remove cam.... 4X4 is MUCH harder. To get the pan off you would need to:
A.) hoist the motor about 2 to three inches off the motor mounts. or B.) drop the front diff out of the way.
Should only take about a hour to remove the cam otherwise. 2 hours to have it running again.
Tell your friend to dial 1-800-different-shop.com next time.
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cold(
Try a quart of Rislone in it. Sounds like a sticky lifter.
Al
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Reck wrote:

    Try a simple valve lash adjustment. 100,000 miles with out a lash setting especially with hydralic lifters, can cause lose of power and excessive valve train noise. Charles
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For sure set the valve lash. Back 30 yrs ago you set the valves almost as often as you changed oil and gapped your points. Modern cam/lifter design and metalurgy along with roller cam's makes valve adjustment needs almost nil but it still is part of proper maint. As for the post about 3K for a cam replacement, I'm in the wrong buisness. I'm thinking (a guess) parts should stay under 650 easily and that is with OEM parts. That leaves2350 in labor. 30 Hrs to do a cam change!

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David Johnson wrote:

    With wear things losen up. I have seen high rail style heads with the rocker arm retainers so lose, the engine will not start.
    Valve lash settings are proper maintaince. Not the 3K mark like older engines, more like the 80k to 100K mark.
    Heck some people think they shouldn't change the spark plugs till the engine barely runs if the vehicle is fuel injected. Charles
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