Author Topic: Engine knocking with only 69k miles... doomed to fail?  (Read 2528 times)

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Offline GeckoAddict

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I posted these over at ls1tech as well, but I figure I'd get your guy's opinions as well.  My '08 GXP is knocking loudly once it warms up (opposite of lifter tick).  I've been told everything from 'lifters, nothing to worry about' to 'rod knock, you're doomed'... thought I'd get some opinions here before I start having my mechanic (my brother) tear it apart.

Audio of the problem after about 15 minutes of driving (it's since gotten louder and more 'metallic' sounding):
https://onedrive.live.com/redir?resid=2073E618F95505EE!4334&authkey=!AEf2SlDZQTA9P7M&ithint=video%2c.mp4
https://onedrive.live.com/redir?resid=2073E618F95505EE!4347&authkey=!AHVdNRkWD9hTWho&ithint=video%2c.mp4


Timeline:
- Feb '09: Bought the car Certified pre-owned in '09 with 12k, started running Mobil 1 Synthetic with the first oil change.  Apparently, she was a rental car before the dealership got it.  Runs great for all 5 years of the warranty
- Summer '13: Starting last summer, she started burning more oil than normal, but I'm also doing a LOT more highway driving so I figured it's the DoD kicking in... now taking 1/2-1 qt every couple months (more than double what she was burning)
- Early March: Cylinder 1 starts misfiring... swap all the plugs, Cyl 1 has minor amounts of oil on the threads and a LOT of carbon buildup.  I also add half a can of seafoam, and then change the oil about two weeks later
- End May: I start noticing a slight ticking upon acceleration when getting to work, barely audible.  Double check oil levels and she's within the hatches, but a little low, so I top it off to the top of the hatches on the stick.
- Early June: It's getting louder now and can be heard virtually all the time when it's hot.  Startup still sounds perfect, but within a couple minutes of driving (and warmer outside temps), the ticking is obvious.  Most noticeable around 1200-1500 RPM, but the speed of the knocking definitely speeds up with the RPMs
- This week: Got a quote from the local engine place, they say 'Piston Noise' and 'internal engine failure... needs replacement'. 

The car is my daily driver and while I occasionally drive it 'spirited', there's only so much you can do on metropolitan freeways and between downtown intersections... it's not like I take it to the track, and she's bone stock under the hood.
« Last Edit: Jun 09, 2014, 06:11 PM by GeckoAddict »

Offline LS4 Racing

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Re: Engine knocking with only 69k miles... doomed to fail?
« Reply #1 on: Jun 09, 2014, 08:49 PM »
Sounds like it could be a rod knock.  This will show up when the engine is hot because the oil is thinner and doesn't take up the clearance between the rod and crank as easily in a worn motor.

We'll see what other folks say, but that's what it sounds like to me.
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Offline RON07GXP

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Re: Engine knocking with only 69k miles... doomed to fail?
« Reply #2 on: Jun 11, 2014, 12:37 PM »
It's hard to say listening on a computer, but it sounds like piston slap or a rod to me. Either way...not good!

It would be nice if it was just a cracked flexplate.  Hope it doesn't cost you too much money.

 
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Offline X Move (Tricky)

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Re: Engine knocking with only 69k miles... doomed to fail?
« Reply #3 on: Jun 20, 2014, 10:06 PM »
..Hope it doesn't cost you too much money.
Wish I could pay engine rebuilders in beer...

I picked up my engine at 40-41k, noticed slight misfire probably around 60-70k.
compression checked at 74k at a friend's school, misfire cylinder 1 bank/no compression.
New spark plugs, wires, switched to synthetic oil and new filter installed. Also used a can of Restore 8 cyl later on.
Coolant flushed and replenished by a dealer at 85k.
Currently at 99,500k as of tonight.
she runs fairly quiet since i've been keeping up with routine maintanance. fuel mpg and obd2 live data have been good and stable. I consider myself very lucky so far.

Hope it's not too serious with yours. I can't view your clip so I don't know how it sounds, but just keep up with maintenance more frequently until it can be rebuilt.
« Last Edit: Jun 20, 2014, 10:10 PM by X Move (Tricky) »
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Offline GeckoAddict

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Re: Engine knocking with only 69k miles... doomed to fail?
« Reply #4 on: Oct 13, 2014, 05:18 PM »
Well I have a bit of an update and an additional question.

Through some garage mechanic work by my father-in-law (maintained city vehicles for years), we were able to get the heads off with the engine still in the car.  Replaced all the lifters, checked all the pushrods and rockers (manual visual inspection...).  From what we could tell by inspecting the cam through the lifter holes that appeared fine.  There was slight discoloration on the cam where the lifters make contact but no visible scratches (example photo:  http://1drv.ms/1xM7aaJ).  The engine is still making noise, and still only once the engine warms up, runs smooth as the day I bought it when it's cold.  Noise is loudest between 1000 and 2200 rpm or so.  For good measure, I also replaced the oil filter under the oil pressure sensor, but it looked clean.

So my questions to this group... what do I look at next?

I could replace all the pushrods and rockers, as maybe they are just slightly warped when they heat up that is imperceptible when cold or without measurement tools.  I could also look at the oil pump and pressures, to see if maybe a lifter isn't getting enough pressure.  I could also give up and assume it's something in the lower end and go the full rebuild route... getting the lower end out of the car looks like where most the labor is.

Offline 91parkave

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Re: Engine knocking with only 69k miles... doomed to fail?
« Reply #5 on: Oct 13, 2014, 10:42 PM »
What lifters did you use? A day I hope you're aware that the dod  cam uses diffrent lifters  for the dod  cylinders. Also A lot of ls motors have what's known as piston slap when cold. Could be your issue
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Offline SlowGXP

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Re: Engine knocking with only 69k miles... doomed to fail?
« Reply #6 on: Jul 01, 2015, 11:59 AM »
Any update to this?  Mine started doing this exact same thing this week.  Sounds fine at idle, but above 1500 RPM its knocking. 



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Offline Pielet

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Re: Engine knocking with only 69k miles... doomed to fail?
« Reply #7 on: Jul 18, 2015, 11:31 PM »
Mine started making this knocking noise as well this past week after being low on oil.  Will be dropping it off at a dealership to get it checked out Monday morning and hope it will be covered under my extended warranty. I'll update if I hear anything.

Offline JaySS

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Re: Engine knocking with only 69k miles... doomed to fail?
« Reply #8 on: Jul 20, 2015, 06:40 AM »
My 06 has a little tick. I have notic it must be a LS thing. Much more of a tick when the oil gets low. I know my oil pan leaks a little. So I'm on top of it , keeping it full. Wait till you put a cam in it. My budys 6.0 LS will sing to you. LOL
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Offline Pielet

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Re: Engine knocking with only 69k miles... doomed to fail?
« Reply #9 on: Jul 20, 2015, 07:00 AM »
Mine is a rod knock. Need new engine according to the dealership.

Offline JaySS

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Re: Engine knocking with only 69k miles... doomed to fail?
« Reply #10 on: Jul 20, 2015, 07:10 AM »
Sorry to here that... Not much you can do for that, but repalce the bearings, up for a rebuild, or go all out for a reman engine.
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Offline Pielet

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Re: Engine knocking with only 69k miles... doomed to fail?
« Reply #11 on: Jul 20, 2015, 08:34 PM »
Yeah it sucks. Only 52,000 miles too.  Just hoping my warranty will cover it.

Offline JaySS

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Re: Engine knocking with only 69k miles... doomed to fail?
« Reply #12 on: Jul 21, 2015, 06:40 AM »
I'm in the same boat with my transmission. Bought a SS Impala, first of the year and the transmission been out since March. But I am saving for the Triple Edge tranny. Plus it will handle future upgrades to the engine.
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Offline batbss06

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Re: Engine knocking with only 69k miles... doomed to fail?
« Reply #13 on: Jul 22, 2015, 05:49 AM »
I'm in the same Boat Jay, saving for the triple edge trans,,, unfortunately yesterday i had to spend 1500 for a trans in my beater pick up just to get one of my cars back up. gxp dead, needs Daves artwork to move again. and i miss my baby, then my tbss needs heavy engine work, spun a main and probably took two rod bearings. Things will align for us soon, Good luck Pielet,
gxp, current blown trans, saving for Trannyman95's art work, gosh i can't wait.  TBSS, current spun bearing, one main two rod, Ouch not Cheep to fix

Offline My325

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Re: Re: Engine knocking with only 69k miles... doomed to fail?
« Reply #14 on: Sep 24, 2015, 12:26 PM »
Sorry to here that... Not much you can do for that, but repalce the bearings, up for a rebuild, or go all out for a reman engine.

If it hasn't spun the bearings and the journals aren't visibly scored it may be worth measuring the journals. 

I've rolled full sets of rod bearings into two motors with slight rod knocks. The journals measured and looked OK.  I put new oil pumps and bypass valves in then drove em 80K + afterwards.

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