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Discussion Starter #1
hey all,

so over the summer I did a partial valvetrain rebuild on my truck. i pulled the top end (including heads) replaced all the little sensors and switches, pulled the heads apart, ground down the valve seats, replaced pushrods and lifters (not valvesprings or rockers or valves), cleaned up everything real good and put it back together with new gaskets. the kicker: i did the valve grinding at 2 or 3 in the morning running off little sleep, and dropped one of the valves on the ground (concrete). i did not see any damage. I ran it for about 10 min at 2500 rpm, and then drove it normally.

ever since then I have heard a ticking noise coming from the drivers side cylinder bank. dont know if its coincindental or not, but i also have a CEL for a lean condition that goes away every restart but comes back after a bit of driving. o2 sensor is new, currently running with a new 2.5" exhaust and no cat. ALSO, revving the engine under load at 2500 rpm or more (basically when gassing it a little harder to get up a hill) i get a popping sound that sounds kind of like backfiring, from the same cylinder area. i dont hear it out the exhaust, it sounds like its just in the engine bay.

i investigated this and narrowed it down to what seems to be cyl 5 causing the problem. the compression is about 20 lbs lower on it than the others (125-230 vs almost 150 for the others). the plug for that cylinder has a sooty black coating (after only 200 miles of driving on this set of plugs) vs all of the others which have a normal tan colour. the ticking noise is coming more from this area than any of the others.

since then I have replaced the oil pump with a new melling one, and during a pressure test with a real gauge i got a little over 50 psi at idle cold, a little over 25 psi hot at idle, and about 50 psi under any gas, which ruled out the possibility of it being a low oil pressure issue.

so my questions are as follows: what did I possibly screw up? are the black plug, low compression, and ticking possibly related? can i be sure it is the valvetrain and not the rings on one cylinder? is it possible i just got a bad lifter and one or both of the valves arent closing or opening properly? was my mistake in not replacing the rocker arms / valves / springs, or in dropping the valve on the floor?

thanks, JB
 

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is it possible i just got a bad lifter and one or both of the valves arent closing or opening properly?
This could be the issue. The rockers might be giving up some of the problem as well. Are the rockers adjustable?
 

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Discussion Starter #3
No, the rocker arms on this engine aren't adjustable; they bolt right to the heads with a single standard hex bolt, not mounted to a stud where you can adjust them, unfortunately. Is it possible I just got bad lifters or something? I got em on eBay and they were like $50 for 16 of them. These are the stock, flat-tappet, hydraulic (I believe) lifters.
 

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Pull the camshaft or use a dial indicator to check the lobes for flat spots. HOPEFULLY it is a bad lifter, but my guess is the camshaft is bad.
 

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Did you take a good look at the plug wire for the #5 cylinder. A light soot coating could mean that that cylinder isn't firing all the time. And it's easier to check than pulling the cam! Maybe swap it (both ends) with another wire and see if that cylinder soots up.

Good Luck
 

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Discussion Starter #9
ill take a look, and make sure theyre not crossed...but the low compression / ticking has me thinking its the valvetrain. i pulled the wire for the injector and plug for #5 and it ran no differently. ill check this before i tear it down again though. thanks!
 
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