tapping noise on cold startup

[torranceandy]

2007 G35 Sedan

If anyone happens to experience a tapping noise on cold startup and can't figure out what it could be, here is a possible cause (it happened to me).

On cold startup there was this tapping noise (I started hearing it after my first 7500 miles) that changed in speed according to engin RPM. You know... the kind that sounds like a valve is adjusted way too loose. The engine ran normally. Once the engine was almost fully warmed up the noise would go away and not come back until the engine had time to completely cool down (and I mean COMPLETELY) so morning startups were a total bummer. After a trip to the dealer and two weeks of waiting (I had a G35 loaner so it wasn't so bad) they informed me the car was done and that the problem was a broken valve spring. From what the dealer tech told me, this is really rare (first time he'd seen it on any VQ35 motor.
Modified by torranceandy at 3:35 PM 4/24/2009

[tollboothwilley]

Wow, ya that is rare. I've never heard of that happening. That would explain the tapping/pinging sound. Its weird that it would go away when it was warm though.

[torranceandy]

I think that's why it took the dealer sooo long to figure out the problem. They'd never seen it before. They had the car for almost 2 weeks before they figured it out. I was convinced it was something in the valve train. First time I took it to them they kinda scratched their heads and changed the oil then said " hey... take it out and drive it for another 500 miles and see if it (the noise... not the motor) goes away.

Yeah right! So I drove the piss out of it. I figured if it destroys itself I get a new motor anyway. It stayed together

[tollboothwilley]

Such a unique problem. Glad they figured it out though...

I can't believe it didnt cause more problems.

[torranceandy]

I was worried about that too but the dealer assured me they checked everything and didn't find any other damage. I guess that syas something for the VQ35HR. About 800 miles since the fix and all is well.

[tollboothwilley]

Crazy. At least you know that there are 2 springs per valve...the other must have kept it going.

Still surprising....

[Canadianbacon]

Hello.. I have a question for you re this matter.. How noisy was the tapping? I have a simular thing happening that also sounds like a tapping sound and also only happens when cold and also goes away.. I also had it in the other day and ofcourse it was not in the am so it was warm and no noise so they told me nothing was wrong. So iam wondering how loud it was.. I can hear mine without putting my head down next to the engine bay but its not overly loud just annoying because i know it shouldnt be there.