Help finding tapping noise.

[85burb]

It is not a ls swap but it is a ls problem. It is a 4.8 in a 07 chevy. It sounds like it has a bad lifter. Like when the roller fails. Well any ways i pulled heads and came and lifters out and everything looks great. The only thing i seen is there is a interesting patteren of the base circle of the cam. Any ideas? Noise comes and goes. It can run a while without it and then it has it at start up and all the time later. Motor has over 272xxx on it. Has almost 40 psi oil pressure hot. I was for sure it was a lifter issue from the noise. I really need help on this. It is a shop truck and me and a guy that worked at chevy were sure it was a lifter. So i ordered all the stuff to do a cam and lifter job. Over a 1000 bucks. My boss is not mad but i feel like a idiot. Thanks!

tick - YouTube

[Clyde65]

I had a belt tensioner sound similar to that on my 4.8, I knew it wasn't the lifters when it started squeaking tho.
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[Clyde65]

Btw, for $1k you could have bought a take out and dropped it in.
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[85burb]

Yes I know we could have got a motor. But our general manager won't buy stuff on line. Hell we could have found a 5.3 for that. When I was looking fore the noise I put a pry bar on to head and exhaust manifold and I clearly heard the noise in cylinder 1 exhaust port area.
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[Jon01]

Did you check pushrods for straightness?

[85burb]

Not yet. They all look fairly strait when I removed the
Will check today.
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[Jon01]

I doubt any are bent unless it's really had it's neck wrung but it's an easy check while you're in there and will give noises like a lifter tapping.

[whitels1]

It's normal for LS engines to sound like sewing machines, and that's what it sounds like. If you didn't see any excessive wear on the cam the crank should look similar. Maybe try a heavier weight oil.

[Jon01]

They are noisy but that is excessive. Even with 200+k on it it should not be clattering like that.

[85burb]

This noise is not normal. Some ware there is something not working right. I have 2 in personal trucks and like 6 at work and they are all quite except this one.
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[BR3W CITY]

Ya thats not normal....even with dual springs and a high lift cam my valvetrain doesn't sound like that.

I'd also be interested in pushrod straightness....I know when you run a pushrod that is too long or too short in these...they sound like a Singer Machine, so I can believe that a bent pr could make the same. Did it change with rpm at all before you tore it down?

[85burb]

Push rods are all strait. Yes if I revved the motor up the tick got faster. It is a factory untouched motor.
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[orngsikL]

is it castech heads? head could be cracked. truck loosing coolant mysterously? any white smoke out the tail pipe at start up?

[85burb]

No major coolant loss that we know of. It is a quart or so low. No smoke
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[orngsikL]

did the underside of the valve covers look like butterscotch pudding?

[orngsikL]

got these marks on the heads?

[orngsikL]

http://ww2.justanswer.com/uploads/Bl...t_loss_5.3.pdf

[Jon01]

It shouldn't have 706's being an 07 thus no Castech issue.

[85burb]

The inside of the valve covers look like golded brown normal color. They are 243 heads if i remember. They are for sure not 706 heads.

[Jon01]

Should be 243's or 799's in 07.

[85burb]

For sure 243 then.
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[coyotes33]

Did you ever figure out the issue? The 5.3 that I just put in my 84 sounds the same
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[85burb]

Yes and no. Yes the noise went away after the cam and lifter oil pump swap. No i never seen exactly what was causing it. I just figured it was a bad lifter. May thousand miles on that motor now and no more noise. Looks like you may be needing a cam swap soon.

[coyotes33]

What do you think?

https://www.youtube.com/watch?v=7Xmh...e_gdata_player

[85burb]

They sound the same. Have you looked under your valve covers? When I put my burbs motor in a push rod jumped out. Maybe take your belt off too and run it. Do you have good oil pressure?
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