I got into my car about a hour ago, and when I turned it over, I hear this knock,knock, knock sound coming from the engine. It is running premium, again I don't know exactly what the last owner did to the car. I had the AC off, and when I turned it on, the noise got quieter, but was still there. No CEL, and after about 10 minutes it stopped. Any ideas?

 

possibly cam chain tensioner......my wifes car had more of a rattling noise though i'd say.....but went to oreilys (only store that had it) it's a 30 dollar part, their's a write up on here of replacing it, it's pretty easy, just unbolt pull out and put new one in basically, but went from loud bad sound to quiet and normal by replacing it

 

x2

 

The odd part is I went out today, and the noise was gone. Were you experiencing this s10novacobaltss?

 

check the belt tensioner and all accessories.

 

the noise got quieter with the AC on because it put a load on the engine and probably the part making the noise. goodluck!

 

Link

 

Mine makes this knock occasionally, maybe once or twice a week but only at idle. Sounds similar to what you are experiencing. I don't really pay any attention to it because it has done it since week 1 of owning the car with 0 miles on it. Hasn't caused me any problems and i'm at 51k now.

 

Mine also makes this sound. It sounds like a diesel running kinda but not to loud as they are. AGREE?

I've been wondering what the sound is, goes away once car warms up(Only does it badly when cold starting). I've heard it is due to direct injection on a small motor makes this noise. I could be wrong.

 

id say depending on miles take it to the dealer...its powertrain so 100k or 5 years

 

diesel sound is the valves opening and closing - normal

 

you cant hear the valves opening and closing

 

Tom is that link you put up for the lnf tensioner that is supposed to be better? I want to upgrade mine finally.

 

timing chain tensioner bro

 

yes...cold starts

 

Can a bad cam chain tensioner cause any damage to the motor long term?

 

tom said it...this is the new version, works much better than the stocker(previous version)


had to replace mine at like 30-40k miles

 

lmao what you are hearing is the lash adjusters and if they are making noise on startup they are starting to go bad

 

again thats wrong...ecotecs have loud valves when cold

 

no ecotecs dont if there is noise in the valvetrain it isent going to be a valve think about how everything works

 

The tensioner loves to make noise sporadically. It's not always constant. This is on my to do list for this winter when the cars sitting.

 

Yes only one tensioner for all of
the Ecotecs.

 

Mr Belvedere is right. You are wrong. Ecotecs in good condition start and run quiet as a mouse. Great motors.

My motor is quiet except for one "bad" hydraulic lifter that ticks sometimes, it comes and goes and i just dont bother with it.

My ecto cavvy wintr btr is quiet as a mouse. Oh both motors have the new tensioner from CED its so cheap its silly not to run one.

 

yessir! probably...

 

I'm glad you posted this, Mine is making this noise badly And it sounds like its under the timing cover, So i'm just guessing its this, I though it might be bearings a pulley at first. I'm just going to try this because i don't have much time for diagnosis since i would super long gay hours.


i would also explain it as sounding kind of like a diesel at idle, kind of like a lifter tick.