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Discussion Starter · #1 · (Edited)
Sorry if this is a common issue but looking for advice. Start off my truck broke a rocker arm and bent 2 push rods. I replaced all rockers and rods. Put it back together and was skipping. I replaced the plugs. Still skipping. Turns out push rod jumped off the rocker. Fixed that. Runs good now but has a tapping noise now. Tore the motor down to the lifters. They all look good. Cam looks good. So I'm thinking its deeper. This is the 2nd motor in this truck. Thinking its another spun bearing. Stock bottom end, heads, cam, intake, headers etc. Its putting down damn near 450 at the wheels when running!. I bought the truck from my brother who had all the work done to it and he was telling me about a 370 you can buy with all forged internals. Don't have a lot of money to drop in it right now as I'm building a camaro to. Any advise would be greatly appreciated!!!
 

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07TrailblazerSS
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Ive seen on the forums this could be piston slap...mine has a similar sound as well
 

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Discussion Starter · #3 ·
How do I get rid of it? It didn't start that tapping until we fixed the skip though. I'm thinking I'm done with the stock bottom end. With this being the second motor and all.
 

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Discussion Starter · #5 ·
Thats what I'm trying to figure out now. Everything is new. We've replaced rockers, rods, and new lifters. Yella terror rockers, trick flow push rods, and factory lifters. It wasn't tapping until we fixed it all. I haven't got into the block yet. Any idea?
 

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I had the same noise last year, about a day or two of hearing that noise one push rod went out and took out my crankshaft and the dealership had to replace the motor.
 

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Discussion Starter · #8 ·
Everything is the exact same. We've even left the valve covers off and individually went through the rockers. That was a hell of a mess!!! I guess I'll pull the oil pan and check the bottom end. Id hate to find the problem, fix it and a year later it do the same thing..
 

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07 TBSS 1SS AWD
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i think your problem is in your valvetrain..

why did it eat a pushrod and rocker... then you fix that... and then the pushrod comes off the rocker..

you have some sort of geometry issue or the parts are just wrong...

id start there... get yourself sorted out there.. then dig deeper if need be...



 

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Discussion Starter · #10 ·
It broke the rocker and bent the pushrods on the driver side. The pushrod came off on the passenger side. I'm thinking the reason the pushrod came off is because it wasn't properly seated when replaced. My mechanic said he drove it and everything was fine. But when I picked it up, different story. I've been there every time since. Just saying. I've measured everything I've replaced and its the exact same as the old. I'm stumped. My mechanic thinks its a broke piston or broke wrist pin. What y'all think?
 

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Discussion Starter · #12 ·
2 bent rods and 1 broke rocker. It was the 3rd one on the driver side.#5 cylinder maybe.? I'm no mechanic by any means. Sorry. It was the last pushrod on the passenger side against the firewall. #8?
 

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Mine is more of a ticking than a tapping. it comes and goes...now i changed the plug wires and it seems to be less....
 

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07 TBSS 1SS AWD
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could be a bad rocker making noise, could be incorrect rocker contact on the valve or pushrod, could be junk lifters, could be pushrods hitting something, could be springs coil binding..

could be TONS of stuff....

the problem is you have something going on in the valve train to be breaking pushrods, and rocker arms....

you need to start there... and diagnose some of that.. check witness marks on parts, have you checked to see what the correct pushrod length is that is needed with the heads on and an adjustable pushrod?



 

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Well it sound funny but durring my tune session, I was getting alot of knock...good 91 gas too. Well it ended up being a clogged cat! Gutted the cats today and the ticking noise i had went away! Now I need to take it back to Garth and have him finish imputing the fuel/spark /timing. Everytime he tried addig timing the truck would knock due to the clogged cat. Now its ready for business!!!!
 
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