I apologize if this question has been asked and answered, but I could not find this issue!

I recently went on a business trip and when I returned my 03 5AT had been sitting for about 6 days (the longest it has sat parked at one time since I got it) and when I got in, it started but the engine knocked VERY loud for about 10 seconds then immediately went back to normal...

First question: Has anyone else seen/experienced this?
Second Question: Is it possible that my oil had settled and as soon as it circulated everything was fine?

2 weeks have gone by and it seems completely normal, no power loss, no gas mileage issues, not so much as click or tick or any other noise you could come up with.

Any input would be great!

Thanks

 

This has never happened to me, but I'd go with the oil having drained from the engine and once the pressure was up, everything was fine.

 

i havn't seen my car for 3 weeks... and won't see it for another few weeks. now i'm paranoid

 

Yes! this happened to me too about two weeks ago.

Didn't drive or start up the car for about 4 days and heard this noise. Sounds like all the oil settled all the way to the bottom and it took several seconds to circulate the oil, that's just my guess.

I thought maybe cause it sat for 4 days, ...4 freezing days.
Whatever it was, it was the scariest sound i've heard yet on the G.

 

I let my car sit for 6 months one time (Depolyment), I don't remember any knocking when I first the car.

 

Mine just did something like that this morning.

 

Mobil 1 0w-40 in winter or year around.

 

All,

Sorry if I freaked anyone out with this, but I can see that I am not the only one.

Also as Deez mentioned in this post, mine also happened during a very cold week...

 

Aahh this happened to me this morning and I was scarerd sh*tless! Went to vegas for a few days, came back, started up and the noise started! Turned it off, 5 minutes later, turned it back on to take video so I could show some mechanics without having to turn it on over and over and it was gone.

There's gotta be some answers! Even if all the oil settled at the bottom, how does that explain the noise? I don't see how that could case anything to KNOCK...?

**Edit**
Nevermind, just found this: The timing chain system is hydraulic. It takes a second for the oil pressure to come up and tighten up the tensioner...so the chains are making the noise.
Here: https://g35driver.com/forums/engine-...-start-up.html

I revived a dead thread for nothing. Yesssssssss

 

I have had 2 maximas and 2 G35's. So I am somewhat familiar with the VQ's

In all of these cars, if they were started cold, moved a short distance and then turned off and allowed to sit overnight, the next time they were started it sounded like it was about to throw a rod.

The first time it happened I thought I blew the motor. Same thing the second time, I opened the hood, the motor was rocking around running on 5 cylinders and knocking like it was going to come apart. Then it smoothed out.

My G35 does the same thing. Probably 5 times in the last 4 years.

It is scary. I suspect it has to do with condensation.

 

Searched and found this thread to my releif.

Let my sedan sit for a week. Hasn't been too cold...60's at night, 80's by day.

Went to retrieve a address from my GPS and decided to start the car and got the worst rattle/knocking i've ever heard from the car. Even worse than that brief 1-2 seconds after an oil change.

Shut the car off and restarted it and was completely normal.

Glad to see that it could be the hydraulic tensioners being drained of oil. Still a little scary and something i'll think about every time i start the car now after a few days of sitting. I've let the car sit for a week before without this happening though. Find it funny that just now it does it.