jethro

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.

Jimbo1367

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

jethro

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!

jethro

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?

jethro

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.

jethro

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.

dan96z71

Did you check your pulleys? I know you said you isolated it down to #4, but I have had pulley tap before when they were getting bad.

jethro

Thanks, I did check the pulleys. Ran it with the belts off, tick was still there.

dave04da

iTrader: (2)

Bent intake valve on 4 from kissing a piston. Ask me how I know...

jethro

I was thinking a similar thought, but I have not over revved it, and when I had the heads off for the lifters, I looked long and hard at the tops of the pistons and each valve. No damage that I can see with my eyes anyway. I realize that my previous posts tie it to #4, but now that I've replaced lifters, I don't hear it there any more. I put a stethoscope on it with the covers off and I cant hear it in the valve train at all. It originally had a truck oil pan, but I switched to a f- body type pan for clearance. I'm thinking the pick up tube is not seated correctly or something along those lines, I have read about the o ring issues. While this motor might not be listed in that group, I did change out the pick up tube with the new pan. I got new o rings and will get the pan off this weekend and give a look. I will also try and get a video/ sound clip as that may help, its not your normal ls valve tick that's for sure.

BigEd_72455

iTrader: (7)

Any further information on this issue? I have about the same problem.

jethro

Work has been crazy so I havnt tinkered with it in a few days. I did replace the injectors, as I thought maybe she was starving for fuel. Had a couple that were pretty gummed up. It does run better, but the tick is still there. Like I have said, its pretty loud and I cant pin point it when I put a stethoscope on the valve train. When I get some time, I will post a video, to let folks hear it. maybe someone can shed some light. I am going to pull the valve springs and check the valves to make sure they are moving freely. Listening to other tick/ tap noises in other posts it still sounds similar to a lifter tap, but they have all been replaced, along with the cam. No idea at this point, but I will keep looking..... to be continued.

BigEd_72455

iTrader: (7)

I had mine at the track sunday. Because of a split end tank, all my stuff was limited because of cooling issues.

had 2 friends listen to the engine with it idling, and they both said that when they moved from one side of the truck to the other, the sound seemed to move. Passenger side said it sounded like driver rear, driver side said it sounded like passenger front. When they swapped sides, same result.

jethro

Hopefully this link will work. Video of my mystery tap.

BigEd_72455

iTrader: (7)

i dont know man. It sounds like a lifter like you said, but thats a loud noise, and it sounds different than mine.

jethro

I'm pretty sure I have ruled out the valve train. New lifters, cam, pushrods, and all the valves are moving freely. When I put a stethoscope to it, I seem to hear it on the front of the oil pan, #1 or #2 maybe. Could this be an oil pump getting ready to go, or possibly a rod bearing? I have great oil pressure 40psi at idle and climbs with RPM as it should. I thought I had ruled out bearing and oil pump because I have good oil pressure. Maybe the bearing is chewed up just not spun, letting the oil get through. One thing I did notice yesterday when I was messing with it, the tick is not there at startup. It comes on as the engine warms up, or if you give it a rev, it shows up and then wont go away. Anybody got any thoughts? This is really starting to short circuit my brain

BigEd_72455

iTrader: (7)

As i have commented, I have been chasing the same problem. I decided it best to pull the engine out and take it apart and see if I could diagnose the issue. I found the below picture for my #8 rod bearing. I had to peck it a couple times to get it to separate so I could remove it from the crankshaft.

my advice, get that sucker out and start with the bottom end for examination. Drain the oil and shine a really bright flashlight at the oil when you drain it or when its in the drain pan. You will more than likely see what looks like glitter..

jethro

Well I didn't want to hear or see that! Thanks for the reply. You had said yours sounded different, How different? Similar enough that I should start pulling apart the bottom end? I really cant think of any reason that a bearing would be going bad, but I am running out of other options at this point.

BigEd_72455

iTrader: (7)

mine went from the sound of a lifter tick to a heavier clunk after 5 passes at the local track. Because of the location of the problem (#8 rod bearing) it was carrying the noise thru the entire block to the point it actually sounded like it was moving from side to side and front to back. But look at it this way, the most it will cost you for peace of mind is an oil filter and oil and a pair of head gaskets. Everything else is reusable.

I had every intention to run it til it **** the bed, but my smart side of the brain over ruled my dumptruck sized ***** and said lets do this the smart way and save some money.

cookseyb

Sounds like a broken or cracked exhaust manifold to me.. FWIW