light chatter/rattle from engine
07-12-2011, 04:22 PM
#21
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the exact same noise and suggestions came my way in another thread.. and my rod bearing was the cause. it was quiet, diagnosed as detonation.. and got worse over the course of 2 months.
Then it turned to a tommy gun sound... and now im doing a full rebuild.
DROp the pan, have it checked.
My clutch noise was easier to hear at low RPM, versus yours is loud and during load it appears, ....same as mine was.
Then it turned to a tommy gun sound... and now im doing a full rebuild.
DROp the pan, have it checked.
My clutch noise was easier to hear at low RPM, versus yours is loud and during load it appears, ....same as mine was.
Last edited by bmccann101; 07-12-2011 at 04:26 PM.
07-12-2011, 04:44 PM
#22
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Well, SH*T. If it's a rod bearing I'm screwed aren't I?! Sigh... it seems like as soon as these guys put in my short block this crap started happening. I'm not good with engines, can you tell me where rod bearings are located?
07-12-2011, 04:50 PM
#23
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Take it to a reputable shop that is not the dealership in have somebody use a mechanics stethoscope. Your rod bearings are connected to the crank and that is in the oil pan it's not a small job .... don't just gas and don't trust a dealer to tell you what they did wrong . take it to another shop and have them find out for sure
07-12-2011, 05:36 PM
#26
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Wait a minute, aren't rod bearings part of the short block?????????? If it IS part of the short block and they ARE faulty, then I can get it fixed under warranty no?!
07-13-2011, 12:19 PM
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Update.... and an odd one at that. So today the temperature was much cooler, the past week its been in the 90s and today its randomly 68ish. I try and test Zazz's theory and what do you know...... there is no sound. The engine sounds completely fine, no oddness whatsoever. I even went full throttle to see if it would produce anything, and nothing happened. Uhhh... wtf? I'll keep monitoring it.
07-13-2011, 02:25 PM
#28
There is lot of armchair expert opinions and guessing here. I would not trust the opinion of anyone who claims to be able to diagnose a sound without having at least heard the sound.
Things vibrate on the car. Sounds happen. You provided no sound clip, no video, nothing. Yet people are coming up with wild theories about the origin of the sound. ...sounds legit, amirite?
You don't drive a luxury car with soundproof body panels. If the car has no CEL and you think something's wrong, put it up on a dyno and see if you can reproduce the sound while you (or the tech) is out of the car and the engine is running and in gear. You can also get your torque curve while you're at it and see if it's making the power it's supposed to - often times a stock tuned Z will ping on the dyno since many of them run fairly lean in low RPM range. You can sometimes see the car pull back timing, resulting in a dip in power.
Taking a car to a mechanic for a random sound that only occurs intermittently has a pretty low success rate in terms of diagnosing a problem. But a road test is no good, since there's so many other sounds going on. That's why you want to try to reproduce it on a dyno.
If you can make the sound happen every time then a good mechanic will be able to locate the source of the sound easily and recommend service options. If I was a nissan dealer I would be laughing my way to the bank with diagnostic fees (and finding nothing) if a customer came in claiming the car had this or that random problem like piston slap.
If you're under warranty, I seriously wouldn't worry about it unless something breaks.
Things vibrate on the car. Sounds happen. You provided no sound clip, no video, nothing. Yet people are coming up with wild theories about the origin of the sound. ...sounds legit, amirite?
You don't drive a luxury car with soundproof body panels. If the car has no CEL and you think something's wrong, put it up on a dyno and see if you can reproduce the sound while you (or the tech) is out of the car and the engine is running and in gear. You can also get your torque curve while you're at it and see if it's making the power it's supposed to - often times a stock tuned Z will ping on the dyno since many of them run fairly lean in low RPM range. You can sometimes see the car pull back timing, resulting in a dip in power.
Taking a car to a mechanic for a random sound that only occurs intermittently has a pretty low success rate in terms of diagnosing a problem. But a road test is no good, since there's so many other sounds going on. That's why you want to try to reproduce it on a dyno.
If you can make the sound happen every time then a good mechanic will be able to locate the source of the sound easily and recommend service options. If I was a nissan dealer I would be laughing my way to the bank with diagnostic fees (and finding nothing) if a customer came in claiming the car had this or that random problem like piston slap.
If you're under warranty, I seriously wouldn't worry about it unless something breaks.
07-13-2011, 05:56 PM
#29
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Thank you wired, I humbly agree 100%. I'm going to see if I can get a recording of the sound, it's just weird that it decided not to do it when I was driving it today. I don't know any good shops around my area (los angeles county) that I can go to, to get on a dyno and see what's going on. It's funny, you mentioned a dip in power, for some reason I seriously think my Z is slower than it should be. That made me think.
And the last thing you pointed out is exactly what I'm thinking - but thats the problem........ I do NOT want my motor to break if this is something that has to do with the pistons/rod bearings. I'll have to see what I can do about a recording to post on here, and I'll try and find a good shop to do a dyno test.
Appreciate the .02.
And the last thing you pointed out is exactly what I'm thinking - but thats the problem........ I do NOT want my motor to break if this is something that has to do with the pistons/rod bearings. I'll have to see what I can do about a recording to post on here, and I'll try and find a good shop to do a dyno test.
Appreciate the .02.
07-14-2011, 07:09 AM
#30
Thank you wired, I humbly agree 100%. I'm going to see if I can get a recording of the sound, it's just weird that it decided not to do it when I was driving it today. I don't know any good shops around my area (los angeles county) that I can go to, to get on a dyno and see what's going on. It's funny, you mentioned a dip in power, for some reason I seriously think my Z is slower than it should be. That made me think.
And the last thing you pointed out is exactly what I'm thinking - but thats the problem........ I do NOT want my motor to break if this is something that has to do with the pistons/rod bearings. I'll have to see what I can do about a recording to post on here, and I'll try and find a good shop to do a dyno test.
Appreciate the .02.
And the last thing you pointed out is exactly what I'm thinking - but thats the problem........ I do NOT want my motor to break if this is something that has to do with the pistons/rod bearings. I'll have to see what I can do about a recording to post on here, and I'll try and find a good shop to do a dyno test.
Appreciate the .02.
Your motor is not going to break unless it's bone dry on oil or you do something else ridiculous/stupid to it.
At the least, you can check out Shawn Church (church automotive) or GT Motorsports, or Tony at Motordyne for dynos. GT Motorsports knows these cars well and would be able to tell you if something was wrong easily.
07-14-2011, 07:23 AM
#31
There is lot of armchair expert opinions and guessing here. I would not trust the opinion of anyone who claims to be able to diagnose a sound without having at least heard the sound.
Things vibrate on the car. Sounds happen. You provided no sound clip, no video, nothing. Yet people are coming up with wild theories about the origin of the sound. ...sounds legit, amirite?
You don't drive a luxury car with soundproof body panels. If the car has no CEL and you think something's wrong, put it up on a dyno and see if you can reproduce the sound while you (or the tech) is out of the car and the engine is running and in gear. You can also get your torque curve while you're at it and see if it's making the power it's supposed to - often times a stock tuned Z will ping on the dyno since many of them run fairly lean in low RPM range. You can sometimes see the car pull back timing, resulting in a dip in power.
Taking a car to a mechanic for a random sound that only occurs intermittently has a pretty low success rate in terms of diagnosing a problem. But a road test is no good, since there's so many other sounds going on. That's why you want to try to reproduce it on a dyno.
If you can make the sound happen every time then a good mechanic will be able to locate the source of the sound easily and recommend service options. If I was a nissan dealer I would be laughing my way to the bank with diagnostic fees (and finding nothing) if a customer came in claiming the car had this or that random problem like piston slap.
If you're under warranty, I seriously wouldn't worry about it unless something breaks.
Things vibrate on the car. Sounds happen. You provided no sound clip, no video, nothing. Yet people are coming up with wild theories about the origin of the sound. ...sounds legit, amirite?
You don't drive a luxury car with soundproof body panels. If the car has no CEL and you think something's wrong, put it up on a dyno and see if you can reproduce the sound while you (or the tech) is out of the car and the engine is running and in gear. You can also get your torque curve while you're at it and see if it's making the power it's supposed to - often times a stock tuned Z will ping on the dyno since many of them run fairly lean in low RPM range. You can sometimes see the car pull back timing, resulting in a dip in power.
Taking a car to a mechanic for a random sound that only occurs intermittently has a pretty low success rate in terms of diagnosing a problem. But a road test is no good, since there's so many other sounds going on. That's why you want to try to reproduce it on a dyno.
If you can make the sound happen every time then a good mechanic will be able to locate the source of the sound easily and recommend service options. If I was a nissan dealer I would be laughing my way to the bank with diagnostic fees (and finding nothing) if a customer came in claiming the car had this or that random problem like piston slap.
If you're under warranty, I seriously wouldn't worry about it unless something breaks.
Not to poke fun at your wonderful advise... but before he goes out and scours for a dyno shop that will let him poke around under the car while its running on a dyno, he might be best suited spending that same $100-200 in dyno time on a diagnostic. Not to mention, are you seriously suggesting running a car on a dyno that you know something is not right on. Sure some things we're are suggesting, throwout bearing, would have no problem on a dyno, but something internal (like a problem with the short block that was recently replaced) and he could have a mess on the dyno floor.
07-14-2011, 12:07 PM
#32
Not to poke fun at your wonderful advise... but before he goes out and scours for a dyno shop that will let him poke around under the car while its running on a dyno, he might be best suited spending that same $100-200 in dyno time on a diagnostic. Not to mention, are you seriously suggesting running a car on a dyno that you know something is not right on. Sure some things we're are suggesting, throwout bearing, would have no problem on a dyno, but something internal (like a problem with the short block that was recently replaced) and he could have a mess on the dyno floor.
Dyno does not mean you have to pull 4th gear runs WOT to redline, dyno means you are on rollers instead of the street, so you can "drive" the car without worrying about where it is going.
I am suggesting a diagnostic - a diagnostic on a dyno.
Of course you can go to a dealer and say "my car is making a funny noise" and as I said previously they will charge you a diagnostic fee but chances are they will either misdiagnose and recommend unnecessary service or be unable to diagnose; you're out a diagnostic fee either way. Dealerships are not very good at diagnosis of phantom problems in my experience, and even worse, they love taking suckers for a ride... but YMMV
The only way I would agree to having a dealer diagnose a phantom noise would be if it was cleraly audible from the cabin and I could reproduce it in a road test whenever I wanted. I would tell the service manager to get in the car and listen to the sound as I drive around, and I wouldn't be satisfied leaving it in their hands nor would I agree to pay for any diagnostic until I'm confident he knows what sound I am talking about. Otherwise IMO you're wasting your time.
Last edited by Wired 24/7; 07-14-2011 at 12:15 PM.
07-14-2011, 03:23 PM
#33
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That's just it. You CAN clearly hear it from the cabin and I CAN reproduce the sound on a road test. It's just weird that these last two days it hasn't decided to produce the sound, even at full throttle. The temperature has been much cooler these last two days. I have no idea whether or not that's a factor. But I can still hear the same type of sound when I start the car after it has been cold, when the RPM's spike up to 2k. I hear for a brief moment that distinct rattle, much more noticeable when the door is open and I start the car. I'll probably have to dyno this thing anyway eventually. At WOT, the car doesn't seem to produce much power AT ALL. It's as if when I put the throttle to the floor, the car actually loses power rather than puts out power. Only a dyno will tell me. But my torque sure as hell does NOT feel like its 260 foot pounds. Whether or not its related, is beyond me. Either something is wrong or my 245/275 + 19' rim setup are significantly slowing me down lol
07-14-2011, 06:42 PM
#34
The timing chain makes a rattle from time to time on VQ engines on startup. Totally normal and never hurt anybody, not sure why it happens. Hell it even happened on my 2000 Maxima, also a VQ. Sounds ghetto and scary but it's harmless.
The same sound during driving I have never heard before.
The same sound during driving I have never heard before.
07-14-2011, 07:08 PM
#35
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Ok so its definitely my mistake and I'm realizing that the sound coming from the engine is not the same one from the cold start - you are probably right about the cold start in that it's nothing. The sound did come back as I was driving back from the gym. It seriously sounds like shaking a can of spray paint of some sort. I really dont know what the hell it is.... sounds like something is loose and just bangs around when I throttle, could be my headers/catalyic converter maybe?? The sound really doesn't sound that harmful at all; in fact, I believe I have heard the sound before on another vehicle. It sounds too familiar to me. Sigh, hopefully I can figure it out. But rod bearings/piston slap definitely doesn't seem to be it.... Those are super loud knocks and this one isn't. Perhaps I'll use my DSLR and see if I can capture the sound for you guys.
lol so if it's cold outside, no engine noise but I get rear clunking (which is so annoying). If its hot outside, I get engine noise and no rear clunking. w00t w00t.
lol so if it's cold outside, no engine noise but I get rear clunking (which is so annoying). If its hot outside, I get engine noise and no rear clunking. w00t w00t.
07-18-2011, 06:25 PM
#36
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Normal. Whether it's called pre-ignition, or pre-detonation or knocking or pinging or whatever is more of a contentious issue; however, that sound is normal at low rpm if you're hard on the gas.
Shouldn't really be putting your foot into it at low rpm like that, anyway. If you are in a hurry, get that b!tch in a lower gear and then twist its tail. You will get much better results.
Shouldn't really be putting your foot into it at low rpm like that, anyway. If you are in a hurry, get that b!tch in a lower gear and then twist its tail. You will get much better results.
^^
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