brcisna

Hello All,

Newbie here
Have been looking to purchase a 350z for some time now. Just curious what peoples thoughts are in regards to what I have found when researching the Z cars for some time now.Seems SO many of these cars ends up with motor knocking issues at around 120k on the clock. I'm sure many of these cars have been revved many times beyond what they should but also have found this knocking starts out of the blue even on cars that have been babied their entire life. The Q35 motors talking.

Just curious what people thoughts are in regards to this issue.

TIA

dkmura

iTrader: (64)

Welcome, but you don't need to post the same question in two different forums. As to the VQ35DE/rev up/HR, your research is faulty. These high-quality engines last well beyond 120K and, depending on their maintenance and service, show no signs of detonation or knocking. Nissan has justifiable won many awards with the VQ series, and that smooth power does speak with affordable and reliable power.

The question should be: what causes "motor knocking" with higher mileage VQs? Like most engines, they require good, clean oil and filters on a regular basis. Take a look at the thread on UOAs being run on VQs that's stickied in the engine section. Poor fuel can also lead to detonation, as many choose to run lower than premium fuel spec'd for the engine.

The last point to be made beyond this are questionable mods and driving by the owners themselves. How many engines have been trashed by new owners who've unsuccessfully tried modding (including FI) their VQ's and simply run the engine beyond design tolerances? And while there's a rev-limiter on the Z, it just takes one missed shift to damage the engine (depending on how badly the overrev was under load).

dcains

iTrader: (15)

What he said!

Atreyu'z 350

An engine is only as good as the owner who takes care of it.

HCO_surfer

I test drive one with 175k and it sounded fine. It's a gross over generalization to say at a certain mileage the motor will be shot.

maxowner

These VQ motors do have their weaknesses. Prior to the 2012MY Nissan/Infiniti used cheap paper gaskets on the oil gallery (found behind the timing chain cover). Once enough oil flow leaks through broken gaskets you will not have adequate oil flow to the rest of the engine (these galleries supply the entire engine). I just picked up a 2003 Maxima that had 192,000 kms on it and it had thrown rod #6. Previous owner indicated failure occured at a red light (idle). When I tore down the engine I did find a leak in the oil gallery which I suspect eventually starved the rod bearing of oil. #6 happens to be furthest from the oil pump. I imagine the motor would have exhibited some knocking to anyone who knew what to listen for.

http://www.350z-uk.com/topic/99607-z...llery-gaskets/

Atreyu'z 350

So the weak link is a poorly designed oil gallery gasket and Nissan has a revised replacement available. And the ECM will throw codes P0011 and P0021 suggesting low oil pressure, which in turn, will throw the car into limp mode to protect itself. Interesting... Not too shabby overall considering that it's not a mechanical part and can be replaced relatively easy. Good info.

maxowner

I wouldn't downplay the significance of the oil gallery gaskets; they are crucial to the longevity of the motor. They're a cheap part to purchase but expensive to install. I don't think I could replace them in my Maxima without pulling the motor. Sure the overall mechanical design of the engine is good but it's not out of this world. Limp mode won't save your engine from low oil pressure if it doesn't shut it down entirely. I know there's been relatively few catastrophic failures but the engine doesn't live up to its reputation. (i.e. Ward's Top Ten)

Don't get me wrong, I like my Nissans (had an Altima SER, currently have a Titan and the Maxima I just bought) but the VQ35 isn't excellent, particularly the earlier ones. They're oil burners until '08, timing chain guide issues until '08, some pre-cat issues, and the oil gallery gasket. I also own an '08 Odyssey with a 3.5L, makes the same HP and has none of those issues.

I think a useful takeaway is to install an oil pressure gauge (maybe your Z's have them already). I'm in the process of swapping a 2013 VQ35 into my Max and hope to enjoy it for many years to come!

Atreyu'z 350

I wasn't downplaying it. I said good info. Its relevance was noted.

rancor

The codes come way too late after the engin doesn't have the oil pressure to properly operate the variable timing control. My Z currently has low oil pressure but hasn't thrown any codes and i'm at 11psi idle and 35psi at 2K rpm. The 350Z at least has an oil pressure gauge so you could catch it early but I don't think any other VQ car has one.

Anyways I'm pretty sure low rpm is the most dangerous time for the oil gallery gaskets causing failures. Idle is the time when you have the least oil flow and you are wasting some of the oil volume pushing it straight back into the pan due to the gaskets.

Atreyu'z 350

Thanks. Good info.

dkmura

iTrader: (64)

Gotta call BS on this post. The VQ35DEs in the Z are not known to be oil-burners except for the '06 rev-up versions. Nor have they had widespread timing guide problems in either the Z or the Infiniti G35. The FWD VQ35s may have had other problems, but for the most part (and with good maintenance practices) the VQ has been worthy of the Wards awards it has earned over the years IMO.

And yes, the Z33 does have a oil pressure gauge and I hope to enjoy the ones in both my street and race Zs for years to come!

Swaglife81

I have 208K on the dash and maybe a used motor, not sure what was done before I bought the car. When taken care of correctly these motors 03+ last over 200K miles. I still get great gas mileage. Only thing to worry about on higher mileage cars is the wear and tire items under the car. Bushings especially.

Atreyu'z 350

114k on mine and still loves to rev.

jimbucks

It is my understanding that a high mileage engine will accumulate carbon deposits that essentially increase the compression ratio. Higher conpression ratio causes knocking unless higher octane gas is used. Z cars already have a high compression ratio to start with so as they acculumate carbon deposits that will increase.

Swaglife81

I can only chime in with my experience. I bought my 03 about 11 months ago with 200k on the clock. Have sense put 9k on the car. Oil stayed clean for 3 months before it started getting dark which is impressive in my eyes. Valve Cover gaskets needed replaced and at 200k that's expected anyway. Everything looked pretty damn good when I popped the valve cover off. These cars tend to consume more oil than some others. Meaning you shouldn't drive 6 months and never collect the oil. I run 93 octane and have never once heard pinging or knock on my 209k car. I have no idea of the vehicle history but it was most likely very neglected from what I've discovered. (Missing trans dipstick, cap, glued vacuum hose, leaky valve cover, cracked air intake, not so good rotors, so on and so on) These engines are not a weak link. There are some components that fail more often than others. If you go to any car forum you will find every car has a weak link to it. 03,04 cobras back 2 cylinders don't get cooling they need and they go faster than the others. New LT1s have a weak link even. Nothing is perfect about any car at 10+ years of age especially. In my eyes when looking for a dependable car that's 10+ years old Nissan/Infinity is at the top of the page. This is coming from a Chevy/Ford go (owned and driven many 4.6, 5.0 Mustangs and LS and LT cars) I'm 35 so I have 20 years of car driving owning experience. A 150-200K motor now is like a 100K motor from the 80s or 90s. If someone picked 2 random engines at 100K and 200k and ripped them apart I don't think there would be much difference. I have no worries pounding on my 209K car if I feel like without that oh **** feeling. If you plan to go forced induction I would have a built motor purchase on standby. As far as big power I think the rod bolts are the weak link and the rods and crank are forged and they can take a beating.