Noise on cold start

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nicholbe

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I have a 2005 LS V8 with 80K miles. When I start the car in the morning I hear a rattling noise for about 2 seconds. If I turn the car off and restart it - no noise, but if it sit for a few hours the noise will come back the next time I start it. And ideas what might be causing this?
 
Need more info.

The most common thing would be the belt tensioner.
Less common would be the AC clutch.
There are, of course, several other possibilities as well.
 
nicholbe said:
It sounds like loose bearings rolling.
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Turn the AC compressor on and off and see if the noise comes and goes with that. Also look at the belt tensioner and see if it is moving around too much.
 
Tried it with the A/C on and off... Doesn't seem to be a difference. Didn't notice any belt tensioner movement. It only occurs after the vehicle has cooled and I go to start it.
 
Are you using the correct oil (0W20 or 5W20)?
When was it last changed (both time and mileage)?
What brand oil filter are you using?
What's the outside temperature there?
 
5W20 - Just changed it last week. Moble 1 with a Wix filter. It's about 50 degrees here.
 
Could it bea timing chain tensioner? Or would tha make noise all the time? This only happens when the motor is cool.
 
nicholbe said:
Could it bea timing chain tensioner? Or would tha make noise all the time? This only happens when the motor is cool.
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It could, but it would be the first gen II that I heard of with that issue.
 
Happens here as well, but not consistently, in both summer and winter time. No drivability issues to speak of, or excess oil consumption.

PP 5W20, Motorcraft filter, every 6mo/10k km.

Just another LS thing or belt drive related.
 
When it's really cold, mine "knocks" every couple seconds for a little bit.
 
joegr said:
Kind of like piston slap?
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I'm no mechanic and don't know much, but I guess it possibly sounds like that. Doesn't do it for long and doesn't seem to go faster if you rev it.
 
hinzy said:
I'm no mechanic and don't know much, but I guess it possibly sounds like that. Doesn't do it for long and doesn't seem to go faster if you rev it.
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Piston slap would vary with engine speed.
 
I tried something different this morning... I turned the key to the on postion for 2 seconds and then started the car. No noise. So whatever take place in a motor quickly to lubricate the top of the motor is taking may car some time. Any ideas???
 
nicholbe said:
I tried something different this morning... I turned the key to the on postion for 2 seconds and then started the car. No noise. So whatever take place in a motor quickly to lubricate the top of the motor is taking may car some time. Any ideas???
Click to expand...

Doing that doesn't add any lubrication. (No electric oil pump.) All that does is give the fuel pump more time to pressurize the fuel rail.
 
So do I have a fuel problem? And if it is a fuel problem, what would be the noise I hear? I just want to make sure I'm not damaging anything. Also, why wouldn't this happen everytime the motor is started - Why limited to cold start?
 
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