Hey all, I did some searching and noticed that others experienced the same issue, but haven't found a definitive answer to it. When the car is warmed up, I get a rattle/pinging in the 1.8k-2.1k range and cannot find the source. My mechanic suggested that it was the precats so I had them gutted and the sound remains (the rattle did not increase or decrease in sound after the gut job).

I know Rochester found the source to his rattle with an idler pulley, but his rattle was was down in the RPM range so I wouldn't think it is that.

And ideas? It only does it when the car is fully warmed up.

 

heat shields? mine was rusted so bad, one clip was broken and would rattle at lower rpm's

 

Sounds like you've got a good mechanic. Get in the car, put it up on the lift (enjoy the ride, LOL) and goose the throttle while he puts a listening device in various areas. You should be able to find it.

Could be the AC compressor pulley, too.

 

Unfortunately, it only happens when accelerating. I can't get it to rattle when at a standstill.

 

I had a similar noise on my 2006 happened during acceleration I found it to be a heat shield under the engine. I forced high temp tape folded over and forced between the heat shield and pipe

 

Timing chainnnnnnn

 

Might be as simple as light pinging. Older cars, carbon builds up, engines ping.

 

fuel grade?

 

Definately sounds like a heatsheild.

 

Heatshield or front precat falling apart inside

Sent from my iPhone using MaximaOrg

 

Like most are saying, check to see if the muffler is hitting the heat shield. Im having the same vibration sound while driving at low rpms. I tried to bend the shield up with a crow bar but its still not enough.. might have to cut that biiiaacchhh.

 

Sunoco 93 all the time.

Scott, I thought it may be pinging, but adding any fuel treatment, octane booster, retarding the timing, and swapping the plugs/coils made no difference.

 

Will have to look at the heatshield. Precats were gutted with no change in sound.

 

If its carbon, its creating hot spots that you might not be able to overcome with octane or timing. Have you tried running some Seafoam through the engine? Its cheap so its worth at least trying.

 

Yeah, I ran Seafoam a couple of times and just ran the 3M fuel system kit two weeks ago.

 

I figured you had tried that. You've been around here long enough to know most of this stuff.

So... AC Compressor and/or AC pulley? I had sold my Max to merovi a few months after getting the idler pulley replaced, and while that (finally) took care of 80-90% of what I was hearing as a rattle, I believe he pin-pointed the remaining noise to the AC. Can't recall what he did, though... whole compressor or just pulley.

 

Thanks for the suggestion. I remember you mentioning the BG cleaning so I figured I would try the 3m kit to see if it helped at all.

I will have to see about the pulley. I wouldn't imagine it being the issue, but you never know.

 

Did you ever figure this out? I have the same problem.

 

I had a very similar problem a few years ago. It was an exhaust heat shield.

 

I get it also - but it sounds more like a stone being tumbled in a coffee can at a steady pace. My catyl. conv's also sound like popcorn machines even while the car is running...

 

I have same issue and have yet to find the source of the sound.

 

-passenger side inner cv joint?
-main chain tensioner weak/clogged?
-AC pulley makes sense, but that would be constant, not only on acceleration.
-by your description it doesn't seem like a heat shield.
valve shims on cylinder 1 or 2?

 

I am leaning toward valve shims for my noise. I'm not sure what the process is for fixing it though.

 

What makes you think that? Different rotational speeds can trip up on a particular resonance frequency. This isn't constant at all.

 

resonance frequency... I didn't realize we were talking about vibration science... I thought we were talking about a rattle. It can occur no matter the resonance. OP states it occurs when the motor is between mentioned RPMs. Every RPM has a frequency, but this is a tumbling rock sound... unless you think of the valve shim as a reed to a saxophone without a tube? By his description I think of a moracca, a tumbling stone sound that bounces around, not a grinding stone on stone sound... different vibration resonance would still emit sound able to be heard by a naked ear(depending on the person) then take into account the oil and it's noise dampening qualities... a never ending conversation blah blah blah, blah blah...

---I didn't say a consistent noise that doesn't change speed or decibels... but if the pulley bearings are bad it seems to me that it would make constant noise no matter the RPM unless other noises from the engine counterbalance the frequency of said noise at a lower or higher RPM... thoughts? idc really

overall... I lean towards valve shims on cylinders 1 &/or 2 OR a sloppy main chain tensioner

I forget, does it make the rattle at idle when u reach that RPM range?

drive with your window down on the passenger side next to a wall/building... listen for if the noise is noticeable at shift change intervals and upon every time you apply more throttle. Sometimes you THINK you only hear it during certain RPMs when it happens more than you realize.

 

That's the conventional wisdom, yes. However, a bad pulley can make all kinds of weird noises. It just can. Strange, but true.

Um hmm.

 

sarcasm... I don't mean to seem rude

agreed... your thoughts on the shims?

 

I think valve shims, going after the timing chain, and gutting the pre-cats are all complex solutions for what is more often than not a simple problem.

Want to rule out (or pinpoint) your AC, Alt and tensioner pulleys? Remove the belt.

 

Just the sound. That's all.

For me, its the same unwaivering rattling tone at the said rpms. It doesn't increase or decrease with rpms.

If in fact this noise is the shims, then it kinda bums me out because it doesn't seem like a simple fix.

 

Post a video, someone will be able to tell you what it is. Now we're just playing the guessing game. I guess low octane gas, lifter noise, low oil, etc. get it....

 

any oil consumption?

 

from RB26 maxima thread:

 

i just posted a video of mine. maybe its the same sound. check thread below please.

 

I see no link

 

http://smg.photobucket.com/user/tool...6fba8.mp4.html

 

knock sensor causing misfires?
coil packs having problems?
timing at 14* during warm idle?

 

I installed headers and don't hear it anymore. Also advanced my timing with car gauge pro.

 

Not the sound I had at all.

 

Darn, I was hoping installing a Cattman Y-pipe would fix this ..., as I thought it is my Pre-CATS, also ...

So, now what? I get that slight purr, also! I took it to a mechanic and he could not discern the noise, but I hear it all the time. I definitely hear it more on the passenger side ...

 

what oil r u running?