I have read some negative comments about the Nissan VQ40 V6 that powers the R51 Pathfinder 05-12, Frontier PU 05-16, XTerra (not quite sure what years) and not to mention Nissan vans in the US market as well as other country markets.
Since I purchased my R51 Pathy Several years ago I have either joined or visited several Nissan forums of the trucks listed above and I have looked at or read prob several thousand posts on the Nissan VQ40 the good the bad and the ugly! One of my main reasons is to see just how reliable this motor is or is not and also to see its failure rate so let's take a look.
Out of several years of looking on several forums I see a total of five total motor failures. Out of the five we have one with a connecting rod failure within 20,000 miles. One that Nissan replaced in 40,000 miles that the customer did not bother to ask how it failed he was just happy they fixed it. The other three were from running the truck out of oil either from neglect or from the cats failing and blowing cat particles into the cylinders causing execive wear (maybe someone can explain this to me I don't quite get it).
So back to failure rate when you consider how many VQ40 V6 motors Nissan has sold just in the US at leased a million the failure rate is quite low actually really low! I am also a member of several Ford Mustang forums and by comparison with a much lower amount of 5.0 V8 coyote and Ecoboost motors sold there is a significant amount of failures.
I am not saying that the Nissan VQ40 is not without its issues we all know of the timing chain issues etc and I am not saying it is the most reliable V6 out there but overall it is a reliable motor that you can put lots of miles on and many people have lots of miles on them.
I should also mention this motor is no slouch it makes solid HP numbers and has real solid torque. A few weeks ago I was on the MA pike merging into traffic and I had to get on it and it just rips! No issues with its power it also pulls my 5,000+ pound camper much better then I ever expected.
Just thought I would comment....
The Nissan VQ40DE V6
Moderator: volvite
I agree with you 100%. As far as I'm concerned, the VQ-series has been a great engine for Nissan considering it's been in the US since 1995. That's service comparable to the ol' and reliable, VG-series V6. The upper timing chain issues aren't really the fault of the engine design, rather, due to Borg-Warner's poor job of quality control and not realizing when the dies were worn that stamped the chain links. If you had a correctly manufactured set of timing chains, the issue didn't occur. You may here of a head gasket issue now and then, but it is usually due to the engine overheating and not directly caused by an engine failure.
I'll explain the catalyst issue for you, which was really more of a problem on the Nissan QR25DE when it first came out in 2002. Both of these engines do not have a conventional EGR system, i.e. one that uses an EGR valve to allow inert exhaust gas to be directed into the intake manifold to control combustion temperatures and reduce NOx emissions. Rather, these engine accomplish is by using the variable valve timing to crack open the exhaust valve during the intake stroke to allow inert exhaust gas to be sucked back into the combustion cylinder along with fresh air from the open intake valve. With the upstream converter being so close to the exhaust ports of the head, any small bits of catalyst substrate that may break off inside of the converter can get sucked into the cylinder and cause scoring of the cylinder walls. Eventually, this process causes a poor piston ring sealing condition. With the 2002-2004 Altimas (and some Sentras), there was an issue with the ECM programming that caused the converter damage which resulted in the issue. Not so much the case with the VQ40DE and I'm not sure if those particular failures were caused by bad converters or an engine management issue that caused those converters to fail.
I'll explain the catalyst issue for you, which was really more of a problem on the Nissan QR25DE when it first came out in 2002. Both of these engines do not have a conventional EGR system, i.e. one that uses an EGR valve to allow inert exhaust gas to be directed into the intake manifold to control combustion temperatures and reduce NOx emissions. Rather, these engine accomplish is by using the variable valve timing to crack open the exhaust valve during the intake stroke to allow inert exhaust gas to be sucked back into the combustion cylinder along with fresh air from the open intake valve. With the upstream converter being so close to the exhaust ports of the head, any small bits of catalyst substrate that may break off inside of the converter can get sucked into the cylinder and cause scoring of the cylinder walls. Eventually, this process causes a poor piston ring sealing condition. With the 2002-2004 Altimas (and some Sentras), there was an issue with the ECM programming that caused the converter damage which resulted in the issue. Not so much the case with the VQ40DE and I'm not sure if those particular failures were caused by bad converters or an engine management issue that caused those converters to fail.
Find Your Forum!