Help with engine problem
 

Hi,
I'm quite concerned about my car at the moment. I was out with a buddy and gave it a couple of hard runs. I was talking at the time and accidentally hit the rev limiter not once, but twice. The second time, I heard a strange squeak/chain rattle sound coming from the front of the car. After further driving, I can repeat the sound even if I'm stationary with clutch in and simply rev to about 4K. I do not hear any noise during the rev or if accelerating until I let off the gas. As soon as i let off to shift, the rattle sound happens. I am able to hear it quite clear in the cabin. I have drivetrain warranty still but have been tuned. So I may have to revert to stock to take it in. I do not have any codes, the car drives normal and I don't hear the noise under light throttle. I have to be giving it a bit or reving upwards of 4K as mentioned.

Anybody have any clue what could rattle/squeak like that?

thanks,
J

If its a rattle noise I would pull the valve covers off and make sure you didn't snap a pushrod or damage a valve spring.

With the age of your engine , it could be belt slippage on the AC..... it could also be other things as well, and checking the top end is good, yet checking everything you can.....only you know where the sound came from and what it sounded like, heck could be clutch chatter, or could be the lousy ls3 chain tensioner just fell apart.... could be ?

My buddy also mentioned the timing chain tensioner. He was figuring if it was a valve spring or rod, i'd be throwing a code. I'll see what he says tonight after hearing the noise. I'm glad i've still got powertrain warranty and will only have to pay my tuner to put the stock code back in temporarily before going for repair.

J

I had a valve spring break and no codes were thrown. I'd check the top end to be safe

just a note - they can tell if its been tuned...sorry to say you dont have a warranty most likely.

Did the overkill Tune raise the limiter?

Nope. The tune left the limiter alone. My warranty will be fine. I know the guys there really well.

I did a bit more driving today and isolated the sound to exactly 4Krpm. I can be coasting in neutral with clutch in and if I rev to right around 4K, it will squeak continually. Anything above or below 4K and it stops. So I'm hoping it's just an accessory pulley (maybe bearings).

J

I really doubt you hurt the engine by hitting the rev limiter. In my opinion the limiter is set with safety calculated in. Not proud to admit it but I have hit mine numerous times thinking I can shift by ear like years ago, the next thing you know your at redline. These things just want to spin. JMO

With the age of your car ,yes it could be the tensioner pulley bearing, other pulley or slipping ac belt....Also you may want to get a speed hut shift light like I have its a great treat to have and is OBD 2 plug and play and programmable for launch and each gear and etc etc..... I too doubt bouncing off the rev limiter did anything...I would check everything you can including the throttle body bolts etc..... something loose may want that harmonics at that exact rpm level, in the old days we would use a piece of hose for a stethoscope and have a buddy rev to the range the rattle came from..LOL

did your AC belt jump a rib on the balancer?

usually if it's engine relates you would hear the noise all the time, it would just get louder as the engine would rev up.

I visited my bud (mechanic) and he gave it a listen. He pulled the serpentine belt and it looked okay physically. He had me start and rev it with the belt off very briefly and the noise was gone. He put the belt back on an the noise was still on. He figures maybe the belt had something on it and was slipping. He recommends changing the belt anyhow since it's a 2011 and cheap to do. I feel much better now :)

J

Well good for you!

Glad to hear. Give all your pulleys a good wipe down with a good cleaner while the belt is off to ensure they are clean as well.