thanks for these information

 

Bingo, that is the SAME exact thing I experienced after I did an oil change. The time I started right after the oil change I heard a real nasty engine clank (worse than normal).

To all those waiting for info, I'm sorry for keeping you waiting, I'm hoping to have this sorted out around the end of the month or early October.

 

The first startup sound from the video sounds very familiar for me on a cold start. I've put a zillion miles on the G so now I just went over 70k. It's not exactly during startup but just a moment afterwards, like the first start in the video, only on cold starts. Yours does sound quite a bit worse than mine, but it does seem to be the same type of thing.

I'd be very interested to find out what exactly this is. I need to change my oil this weekend so I'll make note of how it goes before and after.

 

Sounds like piston slap.

 

I'll let you listen to my 99 cougar on a 0 degree day.
Different sound

This sounds more like a scrape, the other is more like a clack

onomatopoeia FTW

 

I have the same issue 05' G35C, i've been ignoring also but its been happening for awhile now!

 

1. What octane gas to you use, and how often have you been using it.

2. Oil Level, i know you said you checked it, check it again! Ive had engines seize because of it. When you check it, make sure the car has been off over and hour to let the oil drain back down.

3. Do you feel your car has lost a little power when accelerating? You could have a problem with compression in a cylinder which is causing knock issues if you answered yes to this question.

 

Not to thread hijack but I can rule out all of the above in my (noticeably less prominent) case-- I always use 91+, oil level is always good (Mobil 1 syn), and power is as good as usual. Shutting the car off 5 minutes later and restarting it won't produce the sound. Sounds to me like a belt or a chain or a pulley or something, not a misfire or piston slap... just my conjecture.

 

To me the noise still sounds like piston slap based on those I have personally had, especially Ford V8s which still seem to be having issues. If it goes away shortly after starting generally not considered a huge problem.

Regardless awhile back another Infiniti user posted something similar. So basically one additional question is what type of oil filter are you using? The reason for the question is that some filters have a tendacy to lift the bypass valve on startup and rapidly allow it to close. As soon as the oil warms up the problem usually goes away. It may be worth doing just an oil filter change if not using something like Nissan filters to see if it influences the noise.

 

That is a good point, never thought of that... I've been using the generic supertech filters, not sure if they are subject to what you described.
What's the general consensus as to a "really great" oil filter?
Nissan OEM? Napa Gold? Royal purple? Fram? (okay, just kidding on the last one)

 

Nissan OEM I think is generally considered as a very good filter. I am sure there are better ones out there but I don't think you can go wrong with the OEM filter.

What is good about this is you can simply swap filters and refill and if the problem goes away you may have just figured out what not to do during the next oil change.

 

I think I'll give the OEM filters a shot, and see if that does anything for me.
What are the other folks on this thread using?

 

So i'm the only person that has actually had this checked out by a dealership and nobody wants to listen to me?

it's the freaking hydraulic cam lifters. I had it to the dealership a few times and that's what each of the different techs said.

someone take thier car to the dealership so they can tell you the same thing i just said and this thread will be over.

also, it's not piston slap. Of all my years building race motors piston slap doesn't just go away when the motor is worn. It slaps ALL THE TIME due to the increased clearance of a worn piston/cylinder. A completely different sound. Rod knock doens't go away with a warm engine either.

 

The noise tends to go away with a warm engine unless the engine is excessively worn, rod knock will typically not.

It is not unusual in fact very normal in some cases for some piston slap to exist in a piston engine. The piston is a fairly small mass compared to the cylinder and block assembly. The piston will heat up rapidly compared to the block and the excess clearance between the two will be substantially reduced.

One way to test for this but don't go overboard is to start the engine up and shut it down right away before giving the engine a chance to warm up. Remove each plug and drop a few drops of motor oil into each cylinder. If you want to do this over several days you can isolate which cylinder. Now reinstall the plugs and start the engine. If it is piston slap the noise will usually change for a short period then start up again.

Rod knock actually comes in two flavors, one is rod bearing knock. This will almost without fail not decrease with a warm engine. However lateral movement that is wrist pin related may. Both have a tendacy when load is neutral to almost go quiet. Rev matching helps prevent condition.

A good test to figure out the location of the knock is to check its frequency against rpm. Put a mark on the engine damper where it is easy to see as close to top dead center as posible. Now this part could be a little difficult on a 'G' but connect a timing light and watch the mark. If it corresponds to the noise then look up high.

 

I don't think that anybody doesn't believe you.
From what I have seen it doesn't look like there's a resolution, and everybody has just been told to live with it. Seeing as how this symptom didn't exist on everybody's cars when they were brand new, it would seem like it would be something that could be remedied.

That's really what I'm after-- a solution, not necessarily just an explanation as to the source.
So I believe you, but what is to be done about it?