What Might Be Knocking?

[GeneP]

In prevous posts my son had installed on of those Powerdyne "Power Plates" that immediately broke and sent a 1/4" washer down in #1 cylinder. We pulled the washer out through the spark plug hole in 3 pieces. We then pulled the head to find no other damage that could be seen other than the top of the piston dinged up which we cleaned up. The cylinder walls appeared untouched & the valves seated & sealed.

Since we put it back together it knocks / taps for the 1st 15-30 seconds after start up like a sick lifter. Yesterday we pulled the valve covers and started the motor to comfirm which lifter it might be. I pulled both intake & exhaust rockers and could see nothing bent, cracked, or worn. The pushrods are straight. Normally I would expect by putting my hand on the rocker while running I could feel which one was loose, but not this time. I also used a stethiscope and still could not pinpoint where it was coming from other than lower in the motor. I'm I wrong expecting that if it was rod or main bearing damage that the knock would get worse when hot? which it does not. Any other suggestions where this knock or tap might be coming from?

Truck is a 95, 4.3, 2WD, Auto.
Thanks,
Gene

[ctesla]

Gene,
any metal on metal=bad
but she's running so, you definitely didn't tank it; however,
when the head was off, did you crank the piston to its full travel up and inspect the ring lands for possible nicks or sheared off "chips", and then take it down to inspect the side of the cylinder wall surface for marring?

...and even though it sounds like you got "most" of the washer, did you pull the other head and make sure no debri was in the other side?

the "tap" (if not from debri in the other bank still) could be the compression rings spinning waiting for lube to assist in sealing on the wall, as long as no other foreign object has contaminated the other internals.

if the ticking goes away after 15 seconds, and doesn't re-appear, especially during/after warm-up and at highway speeds, I'd do an oil change, to 5W30 and some Marvels Mystery and let it ride.
if it ends up starting to increase in intensity or tap progresses to a rattle, then time to look at salvage yards for a used Vortec.

hope this helps,
chris
nrt racing

[maxwedge]

Did the washer come out in 3 pieces that made up a whole one, a small fragment could have gotten into another cylinder and is imbedded in the top of the piston, possibly touching the head.

[GeneP]

Chris & Maxwedge,
Thanks for the replys. Because it was only one washer that got swallowed and the 3 pieces made up the whole washer, we did not pull the other head. We did run the #1 piston all the way down and inspected the walls very closely and found nothing. We were carefull using scotchbrite pad smoothing the dings on the top of the pistion and making sure there was no high spots that might cause detonation. WE made sure everything stayed clean and kept the cylinder walls clean & recleaned while runing the piston up & down making sure nothing went down between the piston & wall. We're already running 5-30 oil. We changed once at initial start-up then 5 minutes after initial warm-up to include a new filter. We'll add some Marvel Mystery and see what happens. I'm hoping it is a valve train issue because he wants to replace the cam with a complete cam kit (To include springs, lifters, rocker arms, etc.). But that would be stupid to do if its something else in the motor. My 1 car garage is full of motorcycles so we're doing the work in the driveway and its gonna start getting cold soon and that'll suck pulling the motor in the snow. Been there, done that before & now I'm getting too old for that stuff.......(Today my 50th birthday!) (We did motormounts in the snow last year & not fun at all...........

[OverBoardProject]

Happy 50th GeneP