Ticking/ tapping noise, help! - LS1TECH



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Ticking/ tapping noise, help!

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Old 03-14-2017, 03:26 PM   #1
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Default Ticking/ tapping noise, help!

OK, I need a bit of help diagnosing a pretty pronounced tick/ tapping noise. Its a 2007 (gen IV) 4.8 I put in a 75 CJ. Got everything up and running and have a tick/ tap noise. Sounds like its coming from the pass side bank. I've tried the usual suspects. Put the stethoscope on it, no noise from the valve cover, not coming from the bell housing. No codes, no misses. Tried seafoam/ marvel in the case. Pulled valve covers all rockers adjusted properly, no metal in the oil. Seems to be running fine, possibly knock sensor picking up the noise as does not quite pull as it should. The noise follows RPM till about 1200 then either, the exhaust covers it up, or it goes away. Completely stumped, any thoughts?? read through most of the threads already, pretty confident its not a lifter, or a cracked flywheel.
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Old 03-15-2017, 05:50 AM   #2
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Did you listen to the motor prior to installing it? I had a guy at work with a 4.8 truck with 125K ish miles with a typical lifter tick. He replaced PR, rockers thinking thats what was wrong. He also did numerous ATF motor flushes, that cleaned out alot of crud upon draining the oil. He said it sounded like a lifter. He finially gave up and figured he's drive it until it blew up and replace the motor.

About 6 months later his trans went out and while he was swapping out the tranns, he found out the torgue converter bolts all loose and elongated the flexplate. Obviously he replaced the converter bolts and FP and after it was back together, no more "lifter tick".

Just because you dont hear a noise from the belhousing doesn't mean its not from there. I'd pull the dustshields and check the TC bolts.

If that's good, I'm betting its a lifter wheel
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Old 03-15-2017, 11:15 AM   #3
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I did not get to listen to it before I got it. Picked it up from Pacific Fab. They said they did a full leak down and ran it on the test stand. Only had 12,000 miles. Good thought on the TC bolts. I adapted it back to the original t18 4 speed. I pulled the tranny back last week and checked the fly wheel. All the bolts were still torqued correctly and no obvious damage/ wear on the flywheel. Had the stethoscope on it last night, and like I said, nothing from the valve covers. However, I do pick it up more prominently on the primary header tube on number 8. Would you think the lifter wheel still? or maybe a bad/ bent valve? I have triple checked the exhaust for leaks, and that isn't the culprit. I guess its time to pull the head..... Thanks for the help!
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Old 03-24-2017, 06:49 PM   #4
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Well ok I have an update but still have a tick. Isolated it to #4. Had the covers off and backed off the rocker, tick stopped.. no brainer, lifters bad right? Pulled head , replaced lifter, put it all back together, still ticking. Bad lifter out of the box? Crap. Pulled head again, replaced said lifter, still ticking. Not the lifter, tried switching rocker arms around, tick stays on # 4. Any thoughts at this point?
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Old 04-01-2017, 11:05 AM   #5
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So, any ideas out there? Replaced lifter (twice). I switched rockers around, and the tick stays on #4, push rods are straight. Springs look good. The tick doesn't seem to affect power at all. It does seem to go away around 1200-1500 rpm. Could it just be something sticking a little and when the rpm' s get up it frees itself? I tried a motor flush right at the onset of the tick, think another one might help? Me and thre mechanics in town are stumped.
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Old Today, 06:08 PM   #6
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Well, this is just getting stupid. I have replaced the cam and all 16 lifters. I ran it with the valve covers off, checked all rockers and valve springs. No noise from the valve train. But there is a pronounced tapping sound still!! I can't figure it out. No loss of power, just drove it around for and hour.... no metal in the pan. It's there at idle till about 1500 rpm. Seems to go away or at least reduce its volume if just cruising, but put it under load, and tap, tap, tap. It's quite a bit louder than any normal valve train tick I've heard, but like I said, i can't find it in the valve train at all. Does anyone have even a remote idea what it could be? I'm going to drive it till it ***** the bed, but if I can make the embarrassing tap noise go away I will. Any help or suggestions are appreciated.
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