2008 Pontiac G8 (V6) Horrible noise exclusively on cold startup - Pontiac G8 Forum: G8 Forums - G8Board.com
 
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post #1 of 12 (permalink) Old 01-09-2016, 07:01 PM Thread Starter
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2008 Pontiac G8 (V6) Horrible noise exclusively on cold startup

100,600 miles on the car at the moment. Noise is only present after the car has been sitting for about a day and is noticeably worse when the weather is colder. Persists for just a second or two after cold startup and isn't heard again. Here is a video of the problem, sitting for a little over 1 day.

Car was recently in the shop for repairs ( broken front left motor mount and all new struts) dealer said they could not replicate issue. I'll be taking it back soon just thought i'd post here for some advice. No check engine lights/warnings, oil changed little over 2000 miles ago but still due for 100k service.

Could it be the timing chain?
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post #2 of 12 (permalink) Old 01-09-2016, 10:06 PM
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i know nothing about the v6's that come in these cars, but
it sounds like to me a timing chain slapping the tensioner
for a split second, but again... i know squat.

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post #3 of 12 (permalink) Old 01-10-2016, 12:52 AM
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Quote:
Originally Posted by Doxonbb View Post
100,600 miles on the car at the moment. Noise is only present after the car has been sitting for about a day and is noticeably worse when the weather is colder. Persists for just a second or two after cold startup and isn't heard again. Here is a video of the problem, sitting for a little over 1 day.

Car was recently in the shop for repairs ( broken front left motor mount and all new struts) dealer said they could not replicate issue. I'll be taking it back soon just thought i'd post here for some advice. No check engine lights/warnings, oil changed little over 2000 miles ago but still due for 100k service.

Could it be the timing chain?
It could well be the chain, I have had a couple of the V6 VE model commodores and had to do a chain on one of them myself. If it throws a code up which it will when it gets a bit looser you will have to do a chain. If and when it codes first swap the left cam chain tensioner sensor to the right bank and the right sensor to the left bank and start the car. When it codes it should be the same code as before and this will prove 2 things, one it's not the sensor that has failed and two the chain/tensioner is on it's way out. My quote was $2500-3000 to supply and fit soI did it myself from memory about $1000 all in. Chains, tensioners, nylon runners, valve cover gaskets, plug seals, intake gaskets, plugs, coolant oil and filter, new gear for the crank, balencer bolt, gasket sealant and the cam lock tools and pullers. I will help you remotely if you want man.Lol. You can do it.
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post #4 of 12 (permalink) Old 01-10-2016, 01:35 PM
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The video is very short, could you post 60 sec of running? Very difficult to say with such a short video. Is your engine light on ? Check to see if your belt has stretched for starters

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post #5 of 12 (permalink) Old 01-10-2016, 05:04 PM Thread Starter
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It could well be the chain, I have had a couple of the V6 VE model commodores and had to do a chain on one of them myself. If it throws a code up which it will when it gets a bit looser you will have to do a chain. If and when it codes first swap the left cam chain tensioner sensor to the right bank and the right sensor to the left bank and start the car. When it codes it should be the same code as before and this will prove 2 things, one it's not the sensor that has failed and two the chain/tensioner is on it's way out. My quote was $2500-3000 to supply and fit soI did it myself from memory about $1000 all in. Chains, tensioners, nylon runners, valve cover gaskets, plug seals, intake gaskets, plugs, coolant oil and filter, new gear for the crank, balencer bolt, gasket sealant and the cam lock tools and pullers. I will help you remotely if you want man.Lol. You can do it.
Thank you for the heads up! I'm only 18 and this is my first car so much of what you said sounds terrifying to do it myself lol. What I'm worried about is if it is the timing chain could its malfunctioning cause issues in other parts of the car?

My parents have just been telling me to ignore it as the car still runs fine but when something isn't working right it bugs me.

Quote:
Originally Posted by cutlassguy View Post
The video is very short, could you post 60 sec of running? Very difficult to say with such a short video. Is your engine light on ? Check to see if your belt has stretched for starters

Eric
Hey, i'll be posting a longer video of the issue with the hood up soon. This one was so short because it idles regularly after what you see in the video.

No error codes or CEL.

Thanks i'll look into how to do that and report back.
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post #6 of 12 (permalink) Old 01-10-2016, 05:08 PM
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Don't ignore it. Something is amiss and it might be a easy fix right now. Ignoring it could spell disaster.

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post #7 of 12 (permalink) Old 01-10-2016, 05:27 PM Thread Starter
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Don't ignore it. Something is amiss and it might be a easy fix right now. Ignoring it could spell disaster.
No worries I have no intention of letting this go on longer than I have to.
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post #8 of 12 (permalink) Old 01-15-2016, 03:28 PM Thread Starter
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No noise this time, but there is an idle tick. Can't see clearly in the video but the tensioner is moving around quite a bit during idle and maybe it's causing that noise?

Waiting to get my jack back before checking to see if the belt has stretched, but between this and a few other small problems I think I'm just going to trade it in.
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post #9 of 12 (permalink) Old 01-17-2016, 01:04 AM
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It sounds like your belt needs replacing along with the tension-er pulley.
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post #10 of 12 (permalink) Old 02-23-2016, 07:12 AM
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Originally Posted by Doxonbb View Post
My parents have just been telling me to ignore it as the car still runs fine but when something isn't working right it bugs me.
No disrespect to your parents, and I'm sure they did a fine job grooming you to be an upstanding citizen, but this is horrible advice. Get your automotive opinions elsewhere. Your parents must be driving brand new cars all their lives that need gas only.

I have been fixing cars for 30+ years so I've seen a lot of what can go wrong. My advice to my 18 year old daughter is: If you notice ANYTHING change with the car, ie: sounds, smells, vibrations, warning lights - advise me immediately in order to minimize potential damage. If the light is red and it says "OIL", or has a picture of a red gravy boat, pull over as soon as it's safe to do so and take a cab home.

Your noise might be something very minor that could be fixed easily. Maybe not, but driving will almost certainly make it worse.

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post #11 of 12 (permalink) Old 02-24-2016, 05:00 AM
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Could be the a/c compressor. Their known to make some noise at startup but goes away quick. Just a thought.

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post #12 of 12 (permalink) Old 01-11-2017, 07:58 AM
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I had a similar noise so i took off the serpentine belt (Goodyear Gatorback) and started the car without the belt. The noise was gone.

It turned out to be bad bearings in the idler pulley. So I changed the pulley and the noise was gone.

The idler pulleys on Ebay are the wrong ones for the G8 V6. You want the ACDelco part #92221551. It's a quarter the cost that GM will charge you for the same OEM part.

https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

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