GMT 800 & Older GM General Discussion 2006 & Older Trucks | General Discussion

Whats Knocking in my motor?(video)

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Old Jan 19, 2006 | 07:31 PM
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Sounds exactly like my truck, I cant stand it and mine just started doing it at around 60,000 miles. Its even worse when it is able to echo off of a street curb or the car next to me. I feel better now that maybe my problem isnt that serious but who knows.
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Old Jan 19, 2006 | 07:44 PM
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Originally Posted by Flick5959
99BlAcKz71 that nosie if from the number 8 cyclinder and you cant fix it. it is a factory defect since chevy over bored that cyclinder 4mm which makes that knocking nosie and i wont go away untill after the engine warms up. my buddy had that problem with his 03 and that is what he dealer told him.
I think the dealer is full of about the 4mm overbore for obvious reasons, what they probably meant was the piston slap that occurs in most of these motors which occurs when the clearance between the piston and the cylinder bore is too great. The piston to cylinder bore clearance becomes too great either through wear, mismatched pistons and cylinder bores at manufacturing or, a combination of both, which reults in the piston smacking the cylinder walls with a side to side motion and usully goes away when the parts expand from heat and fit more snuggly after the engine warms up.
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Old Jan 19, 2006 | 08:38 PM
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I dont know guys it is pretty loud, I dont know the video really gives it justice but oh well. When I pay off my new tranny and stuff I want to do motor work on it, but I dont know if I should put a cammed lq4 in it or keep the 5.3 and cam that with some arp rod bolts too, then put a 150 shot on top of that? I dont know but i have a lot of time to think...lol
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Old Jan 20, 2006 | 08:19 AM
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sounded just like mine, but mine goes away with a lil' rev
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Old Jan 20, 2006 | 09:06 AM
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Change the oil and cut open the old filter to see if there is any metal shavings or chunks in it. Since it does it only after its warms up, might be a lifter or worse, a bearing on the way out.
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Old Jan 20, 2006 | 01:13 PM
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I'm going to put money on a sticky lifter or a plugged pushrod. If you're getting close to doing an oilchange anytime soon, add a quart of transmission fluid to your oil before your oil change and go drive around for 20 minutes on a hot motor and keep the RPM's moderate, around 2-3000 at all times and watching the oil pressure guage. After your time is up let it cool for 30 minutes, then repeat. Repeat maybe 4-5 times with good, long cool downs and stop if the lifter stop tapping. If by trial number 5 nothing is changed: Stop, change back to oil, consider replacing suspect lifter. Otherwise yank all pushrods out and inspect them for pluggage. Perhaps you have a rocker with insufficient oiling or needle bearings came out. Also, remember to roll all your pushrods on a piece of glass to see if any of them wobble. They should be perfect, not the slightest imperfection.

-Joe
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Old Jan 20, 2006 | 03:45 PM
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I just changed my oil so I wont try that isea for a while. But, when I get a chance I will pull the pushrods out and inspect them along with my rockers. I have never done taken my motor apart other than the fuel rails so are there any how to's on going about pulling them out?
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Old Jan 20, 2006 | 04:22 PM
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take your coil packs off. theres one plug that plugs them to the harness and theres a few bolts. take off plug wires. unbolt valve covers. get a 8mm and unbolt the rockers then pull out the pushrods. its pretty simple.
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Old Jan 20, 2006 | 07:35 PM
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Originally Posted by FogleMotorsports
take your coil packs off. theres one plug that plugs them to the harness and theres a few bolts. take off plug wires. unbolt valve covers. get a 8mm and unbolt the rockers then pull out the pushrods. its pretty simple.
I was gonna try this last weekend and had to abort because I broke my 1/2 to 1/4 inch drive adapter for the 8mm socket. I received a lot of good advice from members when pulling the rocker arms. It really doesnt matter how you unbolt them from what I hear once you get the valve covers off, but when you put them back on I was told to torque them all a little at a time and then once you get close to 22ft lbs of torque, rotate the crank until each set of rocker arms has no load on the springs and torque each one individually to 22 ft lbs. I will be doing this my self this weekend for the second try.
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Old Jan 21, 2006 | 02:47 AM
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I just wasnt sure if I would have to worry about the lifters falling or something like that...
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