*SOLVED* Engine Startup Clanking Noise, 2005 G35 Coupe. (With Video)
 

EDIT:

This problem has been solved.



Go to the 4th page (or post #52 for the story, but the info is right here).

It seems that my particular problem was likely not the timing chain (although it was never clarified) but rather there was an engine bearing failure probably caused by lack of lubrication due to the infamous oil consumption issue. The bearing failed causing metal shavings to invade my engine's oil supply and caused severe scoring and pitting to my camshaft as well as damage to other engine components. It is likely that when it made that clanking noise upon startup that it may have actually been the metal shavings grinding inside of the engine components, having been splashed up along with the rest of the oil that was settled in the bottom of the oil pan.

**The best way to diagnose if you have the same problem causing your engine noise is to drop the oil pan and inspect for metal shavings.**

My saving grace was that I found oil pooling in the spark plug tube seal on plug #6 which prompted them to replace the valve cover, which is when they saw the rest of the damage that prompted me getting a new engine.

If everything looks okay you can be fairly confident that the noise may be related to the timing chain tensioners, as this is a known cause for startup noise as well, but it is much less harmful then having metal fragments in the engine.

Unfortunately for those out of warranty, my particular fix was a full replacement of my engine assembly. According to the dealership it is a fairly common problem which is costing Infiniti a boatload of money. Out of curiosity I asked the service consultant what the cost was to replace the engine and he said $9,300.00. For 6MTs with the rev-up engine it tops just over $10,000.00. For those under warranty, you will walk without paying a cent.



To help anyone else in a similar situation I am including my invoice from the dealership. Maybe it can help those with a similar problem and a less helpful service department get a new engine like they deserve.

http://img693.imageshack.us/img693/5...itiinvoice.jpg



If anyone else finds this thread useful or wants to discuss their engine noise problems that they think may be related, please continue posting in this thread.









Original thread:

My G35 coupe is just about out of its power train warranty (69,580 miles :icon43:) and I need to get this start up noise problem repaired under warranty by Infiniti before it is too late.

The noise only happens on a cold start (after sitting for at least 6 hours) and sounds like a grinding / clanking noise coming from the engine bay as the engine starts up and the rpms temporarily blip up. You can check it out in the youtube video below.

The engine has always been fed premium gas and the oil is perfectly fine. As a side note, the noise still happens after I get my oil changed so oil isn't associated to the problem. I have brought it to Infiniti Metro (Monrovia, CA) twice, first around 42k miles, second time around 48k miles and explained the problem. Unsurprisingly, the first time they claimed not to hear it. Then second time they claimed they fixed it, yet they didn't.

I need your guys' help to try to diagnose the problem so I can know what needs to be fixed when I bring it to Infiniti. The last thing I need is to have this problem build up to a larger problem which can result in failure of an engine component.

Thanks for your input. :)

Edit: I don't know if this is possibly related, but I also notice that if I hold the RPMs between 4k - 5k there is a very slight engine squeak. It only happens from that RPM range (or after that my engine drowns out the squeak). It is very quiet and hard to notice. You need to be driving with radio off and windows down, listening very carefully. It sounds simply like a squeaky bearing. I don't know if this is related.

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what rpm is your car idling at?!? it sounds like it's idling at 2k rpms or something.

anyways.

I can't get a good listen, the short blip of a grind could be the starter. The last videos where it's idling and tapping sounds like a stuck cam lifter. They are hydraulic lifters so if one loses pressure (for any number of reasons) after it has sat for awhile then it will tap loudly until it builds pressure again.

I would have to hear it in person to rule out a rod bearing going bad but it could be. If the dealership didn't worry about it then i doubt it's a rod knocking. Plus it wouldn't stop, it would get louder with revs and never go away.

When the engine first starts it idles pretty high (perhaps around 1200rpm) and quickly drops to about 650rpm within about 20 seconds or so.

The problem with getting the dealership to diagnose the problem is that it only happens on a cold start, so if I drive the car to the dealership and attempt to show the techs, no such luck because the engine is warm. It needs to sit for at least 6 hours. Then, when it finally does it, it will not repeat it again until it is completely cool and has been sitting for a while. When I had the dealership try to fix the problem, I left it overnight and had them try it in the morning. They claim to have fixed the problem, but its also possible that it may have not happened that time. They ended up replacing some belts (completely unrelated obviously).

I am planning on bringing all of the videos with me when I go back, but I'd like to figure it out first so I can have something constructive to say to the techs.

There are variances in the repeatability of the problem, for instance sometimes I will drive somewhere and only have it parked for 15 minutes and it will make the noise upon startup, and other times I have had it parked for two days and it did not make the startup noise. Usually, however, it will make the noise when the engine is cool.

As a side note, I am considering that the grinding noise in the first start may be different from the noise in the other two starts.

I have a lot more video, so if you want to hear it idle for a longer period of time I can post more, I wanted to keep the video succinct in order to avoid scaring people off by having it too long.

Thank you for your input thus far, its greatly appreciated.

Bump for all the technical geniuses.

Ttt

The start up issue kind of sounds like it could be that the starter isnt disengaging form the flywheel fast enough and on its way back into its resting position the gear of the starter is grinding the flywheel. As for that tapping noise I would agree with Binder that it could be a lifter

Sounds like one of the timing chain guides is broken off so it only clacks at start up when the chain is slack but goes away when it idles but hard to tell. Mine did this horrible clacking noise at start up only, we took the oil pan off and found the broken guide in the pan :eek:, did not fix the problem till another guide broke and scorched the cam :5091:

It could be something completely different :dunno:

Thanks guys for the input thus far, I'm beginning to feel like I have a better understanding of what is going on now.

From whats been said so far, these are the current problem candidates:

1. Starter not disengaging quick enough from engine when starting.
-Possible cause: Gear case is malfunctioning.
-Severity: Minimal-Medium (eventually wear out grinding components)

2. De-pressurized (and therefore temporary stuck) cam lifter.
-Possible cause: ???
-Severity:???

3. Timing chain failure of some sort.
-Cause: Mechanical failure.
-Severity: Serious


Hmmm..

Keep the opinions and comments coming, they are very helpful. :biggthumpup:

i have the exact same issue! =( i posted a thread about this a while back and couldnt really resolve it. =\

in for solution!

Interesting, I see you have an 05 coupe as well. I wonder if it is coincidence or not.

yeah. well, i remember someone posting in my thread that its some sort of self check that VDC does. not sure if thats relevant or not.

correction, not VDC. but ABS.

https://g35driver.com/forums/engine-...ng-engine.html

No that is not the same issue. The ABS system checks when you start the car and drive past 10mph (or so) for the first time. It tests the ABS system and it creates a grinding noise for about a second or so. You can feel it in the brake pedal if you depress it while it is testing. I know this because I asked the dealership about it after I got my car and a tech explained it to me.

This engine problem is something completely unrelated to the brakes, it is an engine issue.

Also, if anyone else has any comments about the engine noise, don't be shy! ;):icon17:

i think its time for a tune up!

Bring it to the dealer, leave it over night, and have them diagnose during the cold start.