Hello, great forum here guys. I’m a 1UZ/VH45 guy, but have lots of love for my booboo’s G35.

It recently developed this strange and unnerving internal clunking on the passenger side of the engine that gets worse and more consistent the longer it’s driven, gonna try and attach a video, hope it works.


Using a stethoscope the sound is most prominent coming from the upper passenger side timing cover And also the power steering pump (🤞hoping it’s the ps pump). I can also feel the thump best when holding the stethoscope to these areas.

It’s an 06 G35 5AT RWD sedan with 135k miles, and is likely due for some timing chain/tensioner work as it occasionally rattles after a cold startup and swills oil.

Anyone deal with a sound like this? It drives great, a real trooper considering my girl has flogged it like a stolen car for over 100k miles.

Any insight is greatly appreciated, THANK YALL

 

The rattle at startup is somewhat normal for high mileage VQ's from what I can gather. These VQ's have 3 timing chains, and thus 3 tensioner's, and over time can loose their ability to hold tension, and thus the chains can rattle for a second or two briefly at startup until oil pressure builds. VTC sprockets can also rattle, they can fail internally and/or leak, thus causing a similar noise(s). Nissan had a TSB for VTC rattles, but it was only issued for Maximas and Altimas with the VQ, and not for G/Z's, even though they have the same engine

I have a rattle for a brief second on cold start up only on my 04 G with 166k, it only lasts a split second after the engine fires up, and then its quiet. my 05 with 250k+ did the noise louder/longer as well and even on hot starts occasionally. I was worried about it for a while, but I got my oil analysis from Blackstone and they didn't find anything that would throw up a red flag, so I'm not really worried about it anymore. You can replace the main tensioner through the access cover near the p/s pump; I did mine for peace of mind, and they've made a half dozen revisions to the part. You can try cleaning the VTC solenoids, as I believe the oil flows through them and then into the sprockets. I've had good luck with Bosch and Mobil1 oil filters minimizing the noise. Fun fact, you can use the oil filter off a Nissan Frontier V6 (VQ40), they are a little bit larger.

It could also be a lifter going out, I've heard of some experiencing a lifter getting 'mushroomed' and making a loud clacking noise since the tolerance/valve lash gets way out of spec. The fuel injectors are also quite noisy on these cars, as well as the fuel dampers. I cannot recall, but their may have been a TSB for the fuel dampers. Have you checked or changed the spark plugs recently? Also, have you checked the oil & level? These cars tend to burn oil as they get up in higher mileage.

 

Thanks for the insight and that hot oil filter tip, it definitely uses oil so any safe and easy extra capacity is a plus. I haven't started digging into fuel/spark components yet as the noise doesn't seem at all affected by RPMs, it just sounds and feels like something's randomly knocking around in there.

A couple of months ago I threw my mechanic some business and let him install two ignition coils that were bad; I have the remaining 4 and lots of time to pop them on, but given the random cadence of the sound as well as the accompanying tactile thump I thought it was more a loose component than a misfire, but ya never know!

Thank you again for those pointers. Definitely going to look into all of it in hopes of nailing this down, it's just such a weird problem, kinda spooky even.

 

One thing that came to mind to diagnose the P/S pump is to remove the belt, then you can check the pump and other pulleys as well. You can fire up the engine and see if the noise continues or not.

 

Thanks man! I couldn't replicate the noise yesterday, have to drive it a good long while for the ghost to start knocking around again, but it's a great point you made. Between rain and having to remove a beehive from one of my walls today might be booked up, but I'll post back with results, hopefully could be helpful to folks down the line.

Thanks again!

 

It's been raining on and off every day here in Miami so shadetree mechanicking has been tough, BUT disconnected the serpentine belt powering the power steering pump - shout out to andrewl_v35 - and the noise vanished.

So it's either the power steering pump/pulley, alternator, or fan bracket pulley, but as previously noted the noise/clunk seems to be coming from ps pump.

Going to rebuild the pump and go from there, will post with a final result but if anyone has any insight into that noise it'd be appreciated. Thanks guys!

 

GUYS! It was the alternator. Had enough sunshine this afternoon to swap in a new unit - good lawd that ground nut tho - and all's well in G land.

Thanks Andrewl_v35 for the insight, I hope this post can help someone down the road with a clucking VQ35

 

Yeah working on or around the engine can be tight at times - they shoe-horned the VQ into these cars.
Glad you were able to solve the problem, happy to help out when I can!

 

Usually you can tell immediately when you spin a pulley by hand if there's something wrong with it. There should be ZERO NOISE and a fair bit of resistance, you should only be able to spin a pulley maybe one full revolution. The alternator is the only exception to that rule since it has a bit of inertia and will spin like 2-3 times. If your idler pulleys will just free spin for dozens of revolutions I would start with them.

Go down to a parts house and spin a new one by hand to get a feel for how it should feel. Any make/model will work.