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Premium Member
06 RWD Whitey
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6,023 Posts
Discussion Starter · #1 · (Edited)
I had just dropped my trailer off today and I as I was getting on the highway, I head an unfamiliar noise. It sounded almost like a really loud lifter.
Once I got to cruising speed and merged with traffic, I let off and it stopped. If I would give it gas to maintain speed or set the cruise control I was fine, but any time it got over 2500 rpm the noise would come back again.

So I babied it all the way home and as soon as I got here popped the hood. Well, it isn't a lifter...
Nothing I can find is loose or making any noise that it shouldn't be or doesn't already make. Had a buddy of mine listen to it and he couldn't quite pin point it either.

However, we did figure out that if you put it into gear and load the suspension, it doesn't make the noise when you hit 2500.

Anyone have any idea what this could be? We are thinking flywheel/flexplate???
 

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Premium Member
TrailblazerSS
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1,195 Posts
Well dude not to bum you out or anything but I'm on my 3rd engine first 2 did that exact same thing. The first one blew a hole in the side of the block(37000 miles). The second one I just swapped it out to an ls3
 

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The Lurker
TrailblazerSS 06
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13,844 Posts
Exhaust? Check the header bolts...............
 

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Premium Member
Bet you cant tell
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6,481 Posts
take the hood off and have your buddy lay on the engine and take it for a spin
 

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Premium Member
07 TrailblazerSS Imp
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9,440 Posts
from #7

What a coincidence. Not to steal your thread, Danny, but I have a problem with mine too. Yesterday coming back from Larry's and got a misfire and P0307 after accelerating around a left lane bandit. I lost a cylinder but finished driving home. I pulled valve covers thinking spring broke, looked at the springs, all good, then pulled the plug and the electrode had bent up against the center electrode (TR5.5 NGK). So I put a TR6 back in that I had in it previously and started it up and it runs normal again but now I hear a knock in the "middle" like under under the intake manifold. WTF?? This frikin 100+ heat everyday can leave any time now.
This is the plug and how it looked when I pulled it.

 

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Premium Member
2006 Red Jewel AWD
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11,641 Posts
Someone may have gotten a little aggressive with timing in your tune...not taking into consideration the heat...I hope it's nothing bad!
 

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Premium Member
07 TrailblazerSS Imp
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9,440 Posts
But there were no marks on the end of the electrode, it was just bent over. James suggested that it was a plug that had heat related failure.
 

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Premium Member
07 TrailblazerSS Imp
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9,440 Posts
kevin... it sounds more to me like you have a serious issue... about to get way worse...

explain to me how a plug gets damaged like that?

i bet you pull that head off. and you have marks in the piston....
I just started it up for another minute to listen again. And the knocking is about 3 knocks per second like someone makes tapping a handle of a screwdriver on a solid table top. Its right on top at the middle to rear part of the intake manifold like in the 5 & 6 area.
 

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Premium Member
2006 Red Jewel AWD
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11,641 Posts
#7 is the infamous lean cylinder due to heat...your motor might be going to bed Kev-O! Go look for glittery gold in the oil filter like Greg said...
 

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Premium Member
2007 TBSS AWD
Joined
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31,504 Posts
That's what I'm thinking too. Its worse when its idling than reving up past 2K-3K

The plug I'm thinking may have overheated, weakened and warped in. Only have 20.5* on timing which was done by freemasson
It looks like that plug is too hot from where the timing mark appears to be. Stick with a 6 in the future even with only 20-21 degrees.

For it to be bent like that though, I'd start saving your pennies because its about to get expensive.
 

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Premium Member
07 TBSS 1SS AWD
Joined
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17,281 Posts
so

1. you have a damaged spark plug.

2. you have an internal engine noise.

catch it early before it windows the block.... cut the filter open, and see if you can get a boroscope into the cylinder and see if you have any piston damage... start there. if you have piston damage, you either have a plug with too long of a reach... or something is going on in the motor itself.



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