I dropped my car off at the body shop and when I picked it up... 4 months later, it made a metal on metal sound for the first 2 to 3 seconds on cold starts. After 2 to 3 seconds the sound disappeared.

This only happens on cold starts (car sitting for 8 hours+). The oil pressure at start up is very low. It starts at 0 and after a few seconds it goes to normal oil pressure and the sound disappears.

I am 99% sure the sound is actually the timing chain rattling. The tensioners on the timing chain are controlled with the oil pressure, and I assume that the low pressure is keeping the tensioners from extending fully for a couple of seconds. Once they fully extend, they lock out, hence the reason you do not hear the sound when not starting the car.

Has anyone else experienced this issue? I have the motor out so I will be replacing the oil pump and timing chain tensioners. Sharif also suggested replacing the o-rings on the back of the timing cover. Does anyone have any other suggestions?

 

coud be the vtc (cam sprockets) What type of oil are you using. I doubt the orings are shot. When I worked for infiniti some of the earlier G's had some noisy vtc's. Check the oil level double check the weight of oil. If you are running a thicker oil due to the built motor and turbos it just might take a milisecond longer than normal to reach the VTC's. I personaly have replaced them on q45 motors which are very close in structure.

Ryan

 

I was running a 5W-30 oil, and I know the levels were fine. What exactly do you think would be the issue with the VTC's? You said you have replaced them, can you tell me how you knew they were bad? What was the condition?

 

normally the VTC's will throw a timing code. I do not remember what code it was. I have only seen timing chains and tensiors get noisy with high miles on the motor. But I would not rule that out. Where on the front cover does the noise come from? That would help in finding the problem.

Ryan

 

my car has also done that periodicly. of course the dealer says its normal. I have no idea what causes it since it ocurence is completely random except for that the car needs to not have been driven for over six hours.

 

Heard it before, and its definately the timing chain slapping against the timing cover. Like we discussed, I woudlnt take any chances. Since its quite a chore to remove the front timing cover..etc..etc...I would be changing everything in site: oil pump, timing chain, all the tensioners.

 

what wil happen if left untreated? my dealer won't even admit something is wrong with the car.

 

gatti-man alot of the time you have to hold the hand of the tech when they look at your car so they can pin point the noise. Most of the time by the time the information gets to the tech it is much like I caught a fish this big [--] then by the time it gts to the tech it is this big [--------------]. I used to have these problems on a daily basis. I would take it to the dealer explain the problem have them cold start your car hopefully it makes the noise, then have them start another like car and see if the noise is there or not. I know Sharif has torn down a few of these motors himself so if your gonna tear into it I agree replace the whole shooting match. Good luck with your adventure.

Ryan

 

This might be too obvious, but if there is anything obstructing the oil pick-up screen, such as some leftover liquid gasket material, this can also result in a slow buildup of oil pressure on cold start.

Basically, your oil pressure is too low at cold start, for just a couple seconds. Once the oil pressure rises, the noise goes away. I am correct?

If so, the dealer will need to keep your car overnight, and cold start it in the morning.

 

sharif, my oil pressure shoots up right away and i only hear the grinding noise after the revs shoot up and are at their peak/on their way down. It also sometimes happens sometimes doesnt. Doesnt matter if its cold or hot outside, the only constant is that for it to happen it all it must have sat for atleast 6 hours.

 

gatti-man take it to the dealer and leave it overnight comeback the next day to show the service tech the noise have the service advisor/ or manager start the car. After 2 attempts by the dealer they will need to get a rep from nissan out to fix the problem. Good luck

ryan

 

you know my attitude is f it until I either go fi or until my warranty is going out. originaly I did leave it over night and the noise did happen and they just said it was normal. exact words were some zs do it some don't but nothings broken.

 

I left mine overnight since the car will only make the noise once a day and the dealer actually thought it was the tensioners. I am having the pump, gaskets,and tensioners relaced while it is apart. Might as well.

 

t32gzz congrats on getting a decent dealer, gatti-man I wonder how far you are from the dealer that did t32gzz's car. Might be worth the drive to have a mod friendly dealer help you out. Some dealers are real pistols at getting stuff done.

Ryan

 

It is the lack of oil pressure to the timing chain tensioner for a second or two. My Maxima used to do the same thing if it was parked for a few days. My G did it too.

 

my car has been doing that noise for a long *** time haha... got me scared in the beginning, now i just dont care cause i worry to much about everything... i gotta stopo doing that. haha. i wonder if this will cause damage over time

 

if it is oil pressure then why does my guage go up right when I start the car?

 

I used to have a sheering metal sound on startup...when I pulled my motor this last time, I had 5 teeth missing off of my flywheel!!! The starter must have been lined up improperly..or I stupidly turned the key when the engine was running (although I don't recall ever doing this)

 

woah that's a scary thought since I've been running a lightweight fly for 8k now. I think the noise was there before though but now I'm not sure since I only have like 11k on the car total.

 

Todd, I assume the sound you heard was on every start up, not just cold starts, right? I would think so with that many teeth missing.