Rattle on start

[zerocover]

So I'm currently running Pennzoil Platinum 5w30 in my 2.4i s40. Its about time for an oil change.

On cold start the car gets a very audible rattle coming from the engine at idle, until it gets at least 1/2 way to heated up, then its perfectly quiet.

I was thinking about jumping up to 5w-40 or maybe a 0w-30. IDK which to go with. I think the thicker 0/5w-40 would be quieter at idle, only because its thicker. Or maybe the 0w30 would work better becuase it flows better while cold, Im not sure if I need a 0w oil though the temps dont drop below 20 deg F.

Theres always the possibilty of changing to castrol syntec, I know its a bit more viscous.

Am I even on the right track?

 

[StevieC]

Is it a rattle or more like a ticking sound? Rattling for that long concerns me and makes me think you might have something wrong with your engine...

 

[zerocover]

Rattle but only audible when the engine is at idle and in drive. In neutral its all clear.

 

[StevieC]

I would have it checked, because it doesn't seem normal to me. A little bit of noise from the lifters or timing-chain (if equiped) on start-up is sometimes normal, but the rattle for that long doesn't seem right at all.

I'm not familiar with your kind of car, but something doesn't seem right.

 

[tom slick]

Originally Posted By: zerocover
Rattle but only audible when the engine is at idle and in drive. In neutral its all clear.


That makes me think it is something external like a loose heat shield.

 

[StevieC]

Could be your Catalytic-Converter shield above the converter under the car. This is a common problem that creates a rattle sound.

 

[SLCraig]

Heat shield...

 

[moribundman]

I'd check for snakes.

 

[zerocover]

Just left the dealer today and got a minor part fixed on the front door. No one said anything, after it sat there overnight.

So idk, its prob some loose accessory.

Regardless looking for oil that will make the car more quiet over all at idle. The dealer was running Quaker State conventional oil, before but this is the first real winter so idk if it makes a difference.

 

[SZR48207]

Please describe the rattle in comparison to something we can think of..

Does it sound metallic in nature? How about the frequency of the rattle?

My F150 developed a rattle a while back and it literally sounded like a saw blade slowing to a stop. Turned out to be metal lifts attached to the exhaust manifolds that the factory used to lower the engine into the bay.

 

[TallPaul]

If the rattle is when the oil is not fully warmed up, then the oil already is thicker, so not sure a thicker oil would help.

 

[Norm Olt]

Does the rattle change in intensity (louder) or in frequency(faster/slower) as rpm's vary?

A rattle at startup can become a very expen$ive problem to fix if it is a cam chain/belt tensioner or guide that's going South, etc.

 

[mechtech2]

Since the noise goes away with thinning oil when warm/hot, your thoughts of using a thicker oil would be contrary to fixing it, with the known pattern.
Heat shields are a possibility.

 

[zerocover]

Its a 2007 s40 anything that's wrong with it is getting covered by the dealer. It goes away with any slight touch of the gas, or shift into neutral. The sound only happens at a dead stop at idle.

Its kind of like a jackhammer sound. Metallic in nature.

I thought heat shields too but its not the twang sound of thin metal. Its something more substantial.