Darkstar52

Hey guys, I have a 2006 6MT G35 with the VQ35DE Rev-up, 66k on it. I already tried the G35 forums and wasn't able to get too much help, I've actually gotten the most out of reading posts over here since you guys seem more mechanically inclined

Problem: 2 noises, both start at the exact same time. Tapping/knocking noise from the cylinder, driver's side, closest to the TC cover. Most audible when the stethoscope is on the coil pack. Possible lifter, but sounds heavier. Noise 2: Some type of chain slap from the secondary camshaft timing chain, possibly against the cover. Most audible on the VTC cover, the circle closest to the fender. Both kick in at the exact same time. They are only present when the car is warm, consistent in volume and follow the RPM's, lost to road noise when driving. Moderate volume. No apparent loss of power.

Additional Info: These problems will only start after the car is warm. When the car has been "cold-soaked" overnight, the engine sounds perfect for about 3-5 minutes of idle. Maybe a very light lifter tick. Then boom, both problems arise simultaneously and only take a couple of seconds to kick in. Secondary timing chain appears to hold tension when cold, then lose it upon warm-up. I seafoamed through the vacuum booster, which made the problem louder.

When/How did it start?: About 2 months, ~1000 miles ago. Drove the car hard before a proper warm up during a cold night, no problems, short 3 min drive. Running low on oil, probably around 4-4.2 qts in the eninge. Stupid, I know, I will never do it again. The next morning, while idling waiting in a drive-thru, I heard a loud bang. I thought I got hit or jerked the clutch, but it might have come from the engine. It's still possible it was the clutch, but I don't think I was moving at the time and I don't mess up the clutch very often. I thought I got hit it was so loud.


My Guess: Tensioner? VTC pulley or Cam Sprocket? Just a out of spec lifter? I think if it was the lifter it would be just as loud when it was cold. I remember reading that one of the pulleys has a spring that holds tension until oil pressure takes over, and I'm guessing a small leak causes the spring to disengage but not hold tension. I'm kinda just guessing though. Please let me know if you guys need more info.






So, what do you guys think? I really can't afford to have Infiniti dick around and charge me a ridiculous amount to diagnose it. I'm willing to paypal someone $20 if they can correctly diagnose the problem, since I really want to DIY and not take it to a shop since I'm a college student and low on cash. I really want to make sure I buy the right part(s) instead of dropping 500 on a VTC pulley and have it not fix the problem. Right now I'm feeling

WTFMike

iTrader: (2)

IMO, it sounds like a rod knock on that video. It sounds like a civic I had that I spun a bearing on. I hope for your sake that is not.

quiksilver38

didnt read anything had a few beers but i think its a stuck lifter

edit: after thinking further i still think its a stuck lifter, try some seafoam or engine restore in teh oil

Darkstar52

Thanks for the response man. I don't think it's rod knock, it does sound like it in the video but it's not that bad in real life. The sound is consistent and does not rise with RPM's like every case of rod knock that I've seen, and it's also silent the first 3-5 minutes of warming up so I hope it's not rod knock. I can hear it very loudly when I open the oil cap so it really sounds like the valve train.

It still might be rod knock, I just really, really, really hope it isn't.

WTFMike

iTrader: (2)

I know on my car, when I spun a bearing, the noise got louder/faster with an increase in rpm.

Darkstar52

Thanks man. How much louder did it get? Mine seems to stay the same volume, I can't hear it at all when I'm driving. Get lost I'd say right after 1000 rpm or so, so it's fairly quiet. If I really, really strain I can hear it, but I can tell it's the same volume. I haven't done too much poking around on the bottom end yet.

iideadeyeii

iTrader: (6)

That sounds exactly like my tiburon before I blew the motor. It took one more tank of gas before it finally let go. I slowly started to lose power 1 mile from my house and I had to rev the crap out of it to keep if from stalling. Def sounds like rod knock. My car would only do it at certain rpms at first then constantly the more I drove it

Darkstar52

Thanks guys. Mine has always been constant with the rpm and never gotten louder, nor happened at a certain RPM. I'll poke around the bottom end with a stethoscope tomorrow, and pull the VTC cover and see if I can see anything. If it's a rod knock, I'm royally screwed. It's weird because it has none of the traits of rod knock, while not sounding like a lifter. The way it kicks in and affects the timing chain is also very weird as well.

I'll keep you guys updated.

Gunsmoke

I dont think thats a rod knock, too fast for one at idle and not solid enough. Definitely valvetrain related, could be a tensioner, the KA motors sounded like that when the guides were about to come apart (Nissan ultimately decided they didnt need the culprit piece) It sounds like is originating from the cam gear area, pop that cover off and see if you see anything.

Darkstar52

Thank you! I'm about 90% sure it's the valvetrain too, it's very loud once I pop off the oil cap. I think I'll order the tensioner and chain tomorrow after I pull the VTC cover off. I'm thinking that the lack of tension in the secondary timing chain is creating the second noise, rather than the other way around. If it's the other way around I'm toast.

It's just the oddest thing, I've probably done about 40 hours of research since this started happening and still have not come across one single person who had the exact same problem. Only thing that's been remotely close is this:

Darkstar52

Wow, I swear to god these things always pop up at the last possible second. I literally just posted that and what comes up? The video below. Sounds similar. Makes sense that the ECU is screwed since this kicks in after the warming cycle finishes, and it happens instantaneously.

Now that I think about it, this started happening almost immediately after I lost my key and had to get another one re-programmed to the car through them. If they ****ed up my car while programming the key, I'm going to ****ing lose it. Completely makes sense as to why no one else has this problem.