BlackMacks

iTrader: (3)

I've been reading all the threads I can find, tried to listen to every audio clip and youtube vid I can find relating to this subject, but nothing sounds quite as deadly as I'm experiencing, so I wanted to get some more feedback before I tear into my catalytics:

My engine's an '08 VQ35 with about 73k on it by now, so I'm hesitant to believe it's got any actual internal problems, but the noise and decibel level I'm just having a hard time attributing to loose precat substrate.

The noise I'm hearing sounds like there's a loose ball bearing ricocheting around in my oil pan, it's not subtle in any way, like most I've heard. It's most detectable around idle and the lower rpm's, but it's also there in the upper ranges. Appears to be engine temp affected, when cold it's not there, but after driving for a little while it starts to randomly clatter and bang. It's somewhat rpm dependant, but not consistently, so I'm not leaning towards a repetitive cylindrical issue.

Before I go tearing out my cats and partake of the joy that task represents, I wanted to ask those of you that have experienced the catalytic mambo: give me some feedback on the volume level and rhythm of y'all's cat rattles.

Disclaimer: oil level is good and mostly fresh, it's not "pinging" or "octane knocking", I don't _think_ it's the timing chain, but I could be swayed, it's not related to pulleys or A/C compressor, etc.

Comments always appreciated

MintVQ35

iTrader: (1)

At idle seems weird to me, I know on my 02 I can hear a rattling of sorts when I get off the gas at fairly slow speeds (under 20), once I push in the clutch though it goes away and I do not hear it at idle. Could you possibly get a soundclip/video of what your car is doing?

MrEous

iTrader: (11)

You're sure the sound is coming from the bottom of the car?
Is it only making the sound when the car is moving or can it be replicated while the car is sitting still? Can you make a video/audio clip via cell phone and upload it?
Who installed the engine for you?
I'm curious if something could be loose, like the oil feed, in the oil pan?

Ghost_54

iTrader: (13)

Does your engine noise sound like this: http://www.youtube.com/watch?v=LbfpslK8zUI

TallTom

Maybe a loose heat shield?

BlackMacks

iTrader: (3)

Ghost- that's almost exactly it, but mine's far less repeating, very random and sporadic. Yours almost sounds cylinder-based, tho clearing up like it does during accel makes me question that assumption..........

The sound, tho, is almost spot on, and the volume of it, is also almost a match.

Now that y'all mention it, if I rev in neutral, it really wakes up during decel.

TallTom- it's not a heat shield, or an upper valve train noise, those don't have the "meat", for lack of a better word, this sound does.

Ghost- what'd it end up being? I see the vid is almost 2 yrs old

Xpcgamer

iTrader: (5)

In part 2 of that video the guy ran Seafoam thru his engine and it cleared it up. That really sounds SCARY! Keep us posted.

Ghost_54

iTrader: (13)

Mine did sound like valve slap and after changing the oil and filter three times over a 1000 km and two can of seafoam in over three fill ups during the same 1000 km it started to quiet down. I then ran two treatments of Auto-RX (only available on-line at www.auto-rx.com) followed by a couple more oil changes and everything perk back up. I put the engine noise as being slug, varnish in the engine and carb'd up as well as the oil passage way in the variable timing solenoid be blocked up causing the timing to be messed up and that valve slap sound. Yes that was almost two years when I thought my engine was toast it has been running very strong and without any additional incidents of the engine noise returning.

This video 2 after seafoaming the engine and the three oil changes I mentioned above and one application of the auto-rx http://www.youtube.com/watch?v=bnaOH...eature=related

edit: I should add that the mileage on the car when this happened was around 205,000km and my car now has 252,000km and very strong.

Hope you find the additional info helpful

Rods03Max619

iTrader: (5)

Good Luck on Fixing It....

BlackMacks

iTrader: (3)

Ah, so it was valvetrain related, the repetition of the sound had me leaning that way......

I don't think that's what's going on with my noise, however, it's coming from the bottom of the engine, or perhaps the precat area.....

I'll try to record it and post it, I was just curious to hear from some of those with the dreaded "cat rattles" what their noises sounded like

Ghost_54

iTrader: (13)

That was exactly where mine sounded like it was coming from. Good thing for me I was able to clean things up ... just thought I would share my experience

TallTom

So did you just put the seafoam in the gas tank or did you insert it into the car through a vacuum line?

Ghost_54

iTrader: (13)

I had done both process as well as 1/3 can in the crank but that was before I obtained the auto-rx once I had it I changed the oil once again and followed the cleaning process describe on their web site.

You can well imagine just how un-nerving that engine noise sounded so I was up for running just about any type of internal engine cleaning

Crusher103

iTrader: (10)

that sounds like rod knock.....

BlackMacks

iTrader: (3)

The sound you're about to hear, I've been hearing for weeks, and mostly ignoring, until just the other day, it decided to start missing as well. Now, that, I couldn't stand. I don't care if a car knocks smokes clatters whatever, as long as it runs/stops/drives, I'll motor happily along.

So I went out just now to start unplugging coilpacks while it was running, to attempt to isolate the cylinder with the problem. If I've got my firing order correct, it's cylinder #3 with the valve issue. All the other coilpacks as I unplugged them had a noticeable affect on the engine. I say valve issues, because it sounds to me like I've got a collapsed or stuck lifter on either the intake or exhaust. The thing I can't explain is that this noise has been carrying on for weeks now, but the miss just developed a couple days ago.



Anyway, ignore the neighbor's dog and my country boy accent, and let me know what y'all think. I've got some MMO (it was free, had it at work) in it right now, see if that might un-stick or free up whatever it is, and I'll keep on driving it till I work out whatever plan B is gonna be

Crusher103

iTrader: (10)

find a new engine and get ready for a swap, or get another car. sry.

BlackMacks

iTrader: (3)

Justincase anyone's following this, it's not rod knock. Not that it matters, the engine's got internal issues, but valve issues differ from rod issues in three ways:

Rod knock is the same volume, and is dead-on repetitive, only increasing or decreasing in occurence as the engine's rpm is increased or decreased. AMHIK, BTDT, etc....

Also, rod knock can be stopped by simply cutting off the combustion to that cylinder. Without the combustion explosion slamming the rod down against the crank, it quiets immediately as that cylinder is just "along for the ride" at that point.

Rod knock also does not contribute to an engine miss, the motor will still run fine on all cylinders, as all the valves are opening/closing as intended.

My #3 has valve issues, the dancing around and intermittent occurence of the sound, coupled with the lack of any change when the combustion is halted to that cylinder, confirms it. Either a lifter has collapsed or is stuck, again, not that it really matters, I'm just trying to share some knowledge.

With only 73k on my motor, I'm leaning towards just replacing that rear cylinder head. As much as that job appears to be more difficult than simply replacing my engine again, I can do the work myself, and the cylinder head prices I'm finding are a tenth of the engine prices.

nissandrvr98

iTrader: (3)

...and no codes?

that doesnt sound good at all. gl.

Ghost_54

iTrader: (13)

BlackMacks your engine is knocking just as bad as mine was and from the very same location, seriously try the auto-rx in regular dyno oil before the engine is totally pouched

BlackMacks

iTrader: (3)

Well, it's been, what, a week since I last posted on this? And I think I'm guilty of talking myself into a likely scenario, before really weighing everything and thinking about it all.........Something I'm admittedly guilty of doing, and yet seemingly powerless to prevent it.

Yes, I did get codes relating to this engine miss (but my SES light has been on for pretty much the entire two years I've driven the car) so I didn't immediately think to plug in and check for new ones.

Couple days after taking that video (and remember in my OP where I said the engine had been making that racket for weeks, but just started missing a couple days ago?) I pulled a P0300, which I cleared for grins, only to have my SES light come back on, this time, with a more useful P0303, which coincides exactly with the cylinder that made no change to the engine, when I unplugged the coil.

So I started searching this forum for both codes I pulled, and reading the countless ignition coil threads I found, I'm pretty sold on the idea that my #3 coil has up and failed, randomly, while my car's been making that whatever it is racket, which I mistakenly attributed to an internal valve issue.

My engine is an 08 Quest VQ35, has about 73k on it, so I'm disappointed that it's got a bad coil, but I can't say that I'm surprised, the VQ ignition coil threads are in the thousands......

I'm going to test the #3 coil tonight, hopefully, and maybe even go ahead and swap it to the front, if I confirm it bad, so it's easy to change if/when I get it. The online FSM gives me a much simpler test than the one found in this thread:

http://forums.maxima.org/5th-generat...ighlight=p0303

Using only terminals 2 & 3, it simply says "ok" if resistance is "not 0 ohms" and "NG" if resistance is "0 ohm", seems simple enough, not sure why all of the criss-crossing of all three terminals comes into play.......

Hopefully I'll have some more info tomorrow

Ghost_54

iTrader: (13)

Well I am going to suggest one more time for you to do at least one treatment of the Auto-RX, here's why like you my engine ran very strong after changing the plugs to a step colder and installing NWP spacers the car was a beast until I let my oil run to low and well you have heard my video. I started to have a stalling issue and then the wonderful P0300 for a multi misfire ( you at least got one of the codes and then one that points right at coil #3) ... like you I read just about every thread I could find trying to understand my horrible engine knocking, it wasn't until I read a thread that described how the P0300 can also be caused by the sludge in the bottom of the engines crank case can get pushed up into the "Variable Timing Solenoid" and cause the narrow passage why to become blocked end result was stalling issues and P0300. So as I described earlier in the thread a heavy dose of engine cleaning was started to try and preserve my engine ... seafoam in the gas tank, seafoam in the master break hose, seafoam in the crank case with multiple oil and filter changes. With each attempt the engine did get a bit better, and then Auto-RX wo treatments and another 1500km, with complete oil changes and filter changes my Max returned to its days of being once again a beast.

As you have a coil pack being picked off I would change that as well as the plugs and seeing that they are the ones under the IM you may as well change all three plugs and coils as well as the rear valve cover ( plugs #1,#3, & #5 are all under the IM). That takes care of your misfiring but you still have to deal with the engine knocking which I strongly suggest the Auto-RX in the crank case for a drive cycle to clean up any sludge inside the engine and make sure the Variable Timing Solenoid passage way is also cleared, the auto-rx also help to improve valve seals which in-turn cleans up your engine knock as it did in my second video.

Like you I was very discouraged, and was on the look out for a replacement engine until I found that one thread that pointed me in the direction to clean up the engine internals

mau108

Doing a heavy clean like you did can also cause more problems then needed. I don't know too much about the VQ's and don't know what that noise is. What kind of oil have you been using? I do know the VQ35 are very tough on oil and I would only use a synthetic and follow the manufacturers recommended oil change interval.

Pennzoil Ultra or Pennzoil Platinum and following Nissan's recommended oil change interval should keep that VQ clean on the inside.

Auto-RX has gotten mixed reviews, personally a good synthetic that is known to clean (like the pennzoils I mentioned) would be good. If you want to throw in MMO in the gas tank and oil do it but don't over do it.

Xpcgamer

iTrader: (5)

When I had my E39 BMW at 130K I changed my Vanos seals. After I took everything apart the was a good amount of gunk in the valve cover. BMW tells there customers they can go up to 12k miles before an oil change. Combine this with the fact that most motors take 6 or more quarts of oil people tend to put the cheap dino stuff in it and run it for 12k miles. Once I got everything back together I had a small knock. A buddy of mine who is also a Master BMW mechanic had me run some diesel fuel in the crankcase for 10 minutes at idle. I changed the oil a couple more times after that and they noise went away. Its been running perfect and the motor now has 143k.

BlackMacks

iTrader: (3)

Ghost, my apologies for not addressing your AutoRx recommendation, I was typing yesterday and realized it was suddenly time to go home

I did lots of research on that AutoRx product per your original reply, and like mau108, I also found plenty of bad/overpriced/poor customer service reviews, so I'm not going to spend $30 on a bottle of it. Don't get me wrong, I'm not discounting your experience with it, and I appreciate the feedback, I'm just not going to try it.

Remember I said I've got access to MMO for free here at work, and have some currently in the crankcase, which seems to be helping, the noise is gradually subsiding, but my work commute is only 4 miles, so I'm not exactly running my motor a bunch every day.

I didn't get a chance to test or move my #3 coil last night, I'll get to that this weekend.

BlackMacks

iTrader: (3)

Well, it wasn't the coil, it was the plug. Nearly all of the ceramic surrounding the electrode had disappeared.

And I wouldn't believe it if you'd told me, but that sound I captured on video was the spark arcing out to whatever was closest. I thought the sound danced around a little more than it should've, if it was valve/rod/whatever, but I'm not gonna say I ever suspected it to be because the spark plug had come apart like it did

I tested the #6 coil per the FSM and it passed, as it should've, but after I'd pulled the IM and tested the #3 coil, it also passed, which made me kinda double-take. But once I'd pulled the #3 plug, it was immediately obvious what my problem was. I pulled the #6 plug just for comparison, it looked great, so back in it went, and off I went to Auto Zone for a new plug.

$11 worth of laser platinum fancitude later, oh, and a few minutes of re-assembly, the ole car runs like new! No more miss, no more noise

Now, lessee, what's next......oh yeah, gut the cats anyway, as preventative maintenance