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Patience Of Job
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Discussion Starter · #1 ·
I just hope I am not paranoid but yesterday I started my car & listened to it & it sit there making a whoosh whoosh whoosh sorta like in a pulse style sound. This doesn't do it at all at cold start up, only once it reaches normal 'home' temp. There isn't any power loss, or anything of that nature.

I have searched the forums here & noticed that it was the air compressor, which I am honestly hoping not! I will get a audio sound later today for you'll but in the meantime anyone else experience such a issue? & worse to worse if its the air compressor is it covered my ( Coverage component letter ) as my main powertrain warranty is gone!
 

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Patience Of Job
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Discussion Starter · #3 ·
Gonna have to hear it to give any thoughts.

Rob
here is the video of how this sounds, as mentioned this doesn't do it until it warms up to normal temp. also if I turn the A/C On it stops & then when I turn it off it slowly begins to start the full blown sound again. Please ignore the last 3 seconds of the video as that was a car passing by & not my engine making that sound!

The video is at this link, mods please embed it if you like. https://www.youtube.com/watch?v=Npd6cAcQMFE&feature=youtu.be
 

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here is the video of how this sounds, as mentioned this doesn't do it until it warms up to normal temp. also if I turn the A/C On it stops & then when I turn it off it slowly begins to start the full blown sound again. Please ignore the last 3 seconds of the video as that was a car passing by & not my engine making that sound!

The video is at this link, mods please embed it if you like. https://www.youtube.com/watch?v=Npd6cAcQMFE&feature=youtu.be
I need a bit more......would you have someone hold the throttle at about 800 rpm and record again?

This may be timing chain related....sound will speed up with rpm.

Rob
 

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Patience Of Job
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Discussion Starter · #5 ·
I need a bit more......would you have someone hold the throttle at about 800 rpm and record again?

This may be timing chain related....sound will speed up with rpm.

Rob
Yes I'll get this for you tomorrow its really late now & I will post it up. So it may be timing chain related? But wouldn't you question the thought of when the A/C is on it quietens down & then returns slowly as the A/C is off? Oh my I hope not a timing chain issue blah blah.

Thanks Robby I'll get that tomorrow for ya.
 

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Yes I'll get this for you tomorrow its really late now & I will post it up. So it may be timing chain related? But wouldn't you question the thought of when the A/C is on it quietens down & then returns slowly as the A/C is off? Oh my I hope not a timing chain issue blah blah.

Thanks Robby I'll get that tomorrow for ya.
Although it changes with A/C, it just may be because the crankshaft is being dampened by the additional load......like ringing a bell wrapped in cloth.......if it made no sound whatsoever with the A/C on I'd have different thoughts.

Rob


BTW......congrats.....you're a VIP......polish the new badge.
 

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Patience Of Job
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Discussion Starter · #7 ·
That makes total sense. & I will get you further sound bits tomorrow are there any other specific way you want this or just throttle it to around 800 to 1,000 RPM is that acceptable?

Also yeah I noticed my new badge today when I logged in. Thanks to the ones who added it!
 

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That makes total sense. & I will get you further sound bits tomorrow are there any other specific way you want this or just throttle it to around 800 to 1,000 RPM is that acceptable?

Also yeah I noticed my new badge today when I logged in. Thanks to the ones who added it!
Just the higher RPM will be fine.

Rob
 

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Patience Of Job
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Discussion Starter · #9 ·
I need a bit more......would you have someone hold the throttle at about 800 rpm and record again?

This may be timing chain related....sound will speed up with rpm.

Rob
I have taken a new video of the engine at a normal idle at first & then had the throttle up to about 1,000 RPM & had them hold it there for a few more.

https://youtu.be/zrDJCaha28M
 

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I'd be curious to see the idler pulley to see if it's vibrating in time with the noise. The video is too short to see if the noise if synced to the belt, but it didn't appear to be. The sound does appear to be the "beat" between two rotating things going at different speeds.
 

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Patience Of Job
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Discussion Starter · #11 ·
I'd be curious to see the idler pulley to see if it's vibrating in time with the noise. The video is too short to see if the noise if synced to the belt, but it didn't appear to be. The sound does appear to be the "beat" between two rotating things going at different speeds.
To be honest as my initial posting I actually thought it was the Air compressor acting up, however Robby called me on that mentioning the timing chain which blah I hope not. Because this car just received 4 new pistons as most of you already know!
 

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I have taken a new video of the engine at a normal idle at first & then had the throttle up to about 1,000 RPM & had them hold it there for a few more.

https://youtu.be/zrDJCaha28M
OK, that works for me......laptop has fabulous speakers.

You are hearing a worn cam chain.....I'll go into detail in a minute......it will cause no harm, btw.
I would stop by the dealer that successfully repaired the car and have the mechanic give it a listen and get some printed documentation of the concern since you indicate a warranty extension of some sort has been granted.


OK, I will do my best to simplify what's going on here, but first, I need you to visualize a bicycle chain.
This is called a roller chain and it is a roller chain that is used to drive the camshafts from the crankshaft.
The ratio is two to one.....meaning every two turns of the crankshaft results in one turn of each camshaft......so, like a bicycle, there is a ratio change.......doesn't matter much to my response other than to give an idea whats going on in there.

We use a term to describe chain wear.....it is called 'stretch'. It doesn't actually stretch though......what occurs is wear takes place at each link attaching pin and wear also occurs at each roller that the attaching pin goes through.
So, the wear points are were each link rides and is secured by the staked pin and each roller, having a bronze bearing within.
Also, wear occurs at each sprocket tooth.

Chains do not wear 'stretch' evenly......there will be an area of travel from gear to gear where the chain has minimal free play and as it continues down its path there will be more free play.......

Back to a bicycle (or motorcycle for our two wheeled members)......a specification for free play is provided by the manufacturer. To correctly perform a adjustment the drive wheel is turned by hand while feeling the free play at the longest area of the chain between the sprockets.....as you continue to turn the wheel you will feel the chain tighten and as you continue to turn the wheel you will feel the chain loosen. The free play adjustment is made when the chain is at its tight spot and this is to prevent the chain from over loading the engine or pedal output bearings as well as preventing either machines rear wheel bearing from being overloaded.
If we were to adjust the chain at its loose spot, everytime the tight area is running across a sprocket, the sprocket itself as well as corresponding bearings experience a tremendous, momentary load.

Back to the Cruze: the car has a hydraulic chain tensioner driven by engine oil pressure, and two nylon chain guides. The tensioner has a one way sprag.....a shaft with little gear teeth that has a spring steel pawl.
The gear teeth are there so the tensioner won't retract at engine shutdown.......they are far enough apart though, to not allow the tensioner to 'lock' and create a too tight situation.
If the engine were to operate with the chain rotating tight and then too tight the nylon guides would be destroyed.

Whew, fingers getting sore.
This chain, if it could be taken apart at one of the pins, is about 7 or 8 feet long......essentially twice the height and distance between cam gears added together.
This means the chain will pass the same point around every fourth or fifth trip around the sprockets which lines up nicely with the timing of your sound.......and slowly speeds up as RPM rises.
You are hearing the chain slap 'lightly' as the more worn section passes the upper guide between the cams.......I have heard this sound on other 1.4's at the dealer I hang out at........they have never seen a actual failure that was a result of 'chain stretch'.

I don't know the pin count of this chain but it likely is in the vicinity of 130 to 150.......so 260 to 300 wear points........btw, we are talking thousandths here......not a quarter inch or anything that dramatic.

Hows that for the longest winded method of saying don't frett over it?

Rob
 

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Patience Of Job
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Discussion Starter · #13 ·
Now that some education for me! Thanks Robby for the detailed response here, learned more everyday from you guys/gals. Ok now leads me to my next question; I can take it into the dealership for documentation; then they will want to do a diagnostic which is anywhere to a $100 dollars at this dealership. The fee is fine but just for documentation ? Also if they do that & find its the timing chain they will promptly want to replace as its considered bad right?;

Then if they say ok it needs replaced, w/ my new warranty I am still a bit shady on it as i don't know what it all covers as the letter is just very brief but it describes it pretty well I just don't know what is included & what isn't.

So maybe you can also help me w/ the includes & what's not included on my CCL ( Coverage Component Letter ) Engine - Its states as follow :

" All internally lubricated engine parts; block; heads; manifolds; oil pan; mounts; seals; gaskets; starter; flywheel; harmonic balancer; belt tensioner; water pump; the entire pressurized fuel system; injectors; all internal engine actuators & electrical components; control modules & module programming; & throttle body. " - I am assuming the timing chain & gears gaskets etc are all covered under this letter.

Now I just like to get a run down on what is included not as much what isn't so I know when I am at the dealer they can't tell me oh this isn't included & then try stick me for the bill & "double dip" on me. Also FYI my powertrain has expired! so anything will need to be covered on this coverage letter.
 

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Since the chain is a internally lubricated part, it is a covered repair.

The difficult part is calling it a failed part......it has not failed.
If you wish to persue it though, you have a leg up on the situation.

You would take it to the dealer, say it runs awesome.........never better......but, you are concerned over this sound that was not there prior to repair and wish to have it resolved.

Since this is now a 'ever since you' situation that seems to be a oversight on their part, they may.....may.....emphasize MAY, pursue the concern.......and since (I assume) you have already invested money in a diagnosis, you might escape another hit.

I will emphasize, this is not critical and as normal wear continues the tensioner will extend to the next sprag stop at which point the noise will likely become imperceptable.

Resolution would require a chain, the tensioner, the guides and maybe....the sprockets.

Rob
 

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Patience Of Job
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Discussion Starter · #15 ·
Well I may just let them look at it as you mentioned & no need for real concern at this point. I do have another question for you robby, when I was driving today I had to stop at a red light & I turned my fan speed onto 1 & I felt the motor bog way down & the motor felt like it was rocking back & forth & rpms dropped some but came back up to normal & rpms settled & that was that.

- Never experienced this issue either until the engine fix. Maybe I am a bit paranoid & over reacting a bit maybe?
 

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Well I may just let them look at it as you mentioned & no need for real concern at this point. I do have another question for you robby, when I was driving today I had to stop at a red light & I turned my fan speed onto 1 & I felt the motor bog way down & the motor felt like it was rocking back & forth & rpms dropped some but came back up to normal & rpms settled & that was that.

- Never experienced this issue either until the engine fix. Maybe I am a bit paranoid & over reacting a bit maybe?
Sorry for my slow responses......I'm on 3 forums right now.

The fan question.......that's a weird one......just the fan or was it in a A/C enabled position......meaning the compressor will engage as soon as the blower is switched on?
I'll guess it was and you kind of surprised (for lack of a better term) the ECM and there was a delay in increasing the RPM to compensate.

Try it a few more times and see if you develop a pattern.

Rob
 

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I'm inclined to think the A/C compressor kicked in. The ECM might have to re-learn the load the A/C puts on the engine so it can adjust ahead of time and not wait for the RPMs to drop to react.
 

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Thank goodness people are talking about this. My Cruze has been making that rhythmic whoosh whoosh sound for over two years. If asked about it while bringing the car in for other things at least four times! The dealer says its nothing, and they can't find what causes it, and haven't heard this from anyone else! What is going on?
 
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