Excellent write up! A bit confused though. All 2017+ are VQ35DD. 2013-16 are the port injected VQ35DE.

 

May have had that backwards. Direct injected VQ35, so yes it is the DD. Edited post.

 

**** you did all that yourself?? Must have some sweet tools and shop set up!!!!

 

For sure on the amazing work you did. 185k is a lot of miles. Do you figure she did 5k oil change intervals with the recommended 0w20?

How about the CVT? Edit. I just saw your CVT thread. Awesome.

 

She always followed the onboard schedule for service whatever interval the vehicle said it needed changed, and, it was all done at Nissan prior to us dating about a year ago. As far as tools/shop, I have a home two car garage. Engine lift, stands, etc I do have. Alot of power tools (electric ratchet, impact, etc). I typically do alot of VW and Audi stuff, and engine swaps and etc in general for side work. I have worked on some older Nissan engines (2000s Frontiers and etc). I have something in my personality where I always want to figure things out. It is crazy to me the dealer costs and labor rates so I avoid at all cost. These engines list at around $10,500 currently for new. I do not know if they list a timing chain service interval, but for a $10000 engine I am saying around 150k miles on a vehicle that was maintained is likely around the mark. In the case of this engine I did at 185k I personally felt it was maybe a couple thousand miles or less away from catastrophic failure. Chain was loose and hanging under the top guide, and loose on the non-tensioner side as well, tensioner was maxxed out. No plastic guides were broken, just worn down.

 

Yep, sludge is probably the culprit. I've tightened up the oil change interval on my '19 from 5k to 4.5k, and may tighten some more [thanks PoManz for the tips]. My '02 needed timing chain work due to a blown head gasket around 155k miles just over a year ago. Just put a new alternator on the '02 this past weekend and boy does it run sweet now. This weekend is rear brakes on the '02.

BTW, at the oil change, I drain it while hot and let it drain overnight with the oil filter off, thinking I can get the most sludge out as possible.

 

Having followed these vehicles since 2019, I would say you are the first one to post DIY major engine repairs on a 2017+ Good stuff.

I've have read of some 200-300K mile VQ35's in the past, still on original chains, but not on a R52 pathfinder. People generally get rid of them before disaster strikes. In the case of your GF's PF, it probably would have gone to the junkyard had it not been for you. Best case a shop would install a good used engine and trans for $6-7K maybe? Like you say, new replacement engines are out of the question. A nephew of mine had a 2000 model year Pathfinder 4.0L, 5spd MT that finally died at ~250K miles. I suspect a chain or something valve related because it lost compression suddenly and catastrophically.

Nissans don't have an oil life monitors of sorts, which is why I was curious You set the maintenance minder intervals (miles/times) yourself in the driver's settings and it just counts down and sets a message when that mileage has been reached. It's the same today, right up to the 2022 Frontier I recently bought.

 

Very interesting, I figured I was one of the first. Unfortunately even a used engine from a salvage yard is around $6000 down here in GA, which told me they most likely are failing somewhere if the price is that high already. I will check the oil change interval in the vehicle I never paid it much mind. The 2000 or so model engines were pretty good but I have ran into a few timing and oiling failures on the Frontiers (04-06). Hopefully the post will help someone current or future. I just knew when I looked there was literally nothing except one terrible youtube video that did not provide anything accurate. Eventually I will post up some photos. I am not usually a forum guy, just did this to help out.

 

If you do get the time to post up some pics, that would be awesome. I wonder if used prices on VQ35DD's are up because of all ones you read of on the innerwebs that are sludged up beyond repair. I'm so paranoid about that I've been changing the oil on our 2019 every ~3500mi and I use synthetic 5w30 as opposed to the recommended 0w20. We're nearing 80K miles on our 2019.

 

That is my guess. These engines are failing in some instances and my guess is surely sludge. Like I mentioned it sucks, but at around 150k I would be prepared to do timing chains. This is also a chance to clear sludge from some of those vital areas. Making it 185k miles is pretty good, luckily she has a good enough ear to know, and I am skilled enough to know when the chain is slapping it is time to turn it off. No reason to risk bending valves. My guess is by the time you are ready to do chains HOPEFULLY Cloyes or another company that makes quality upgraded kits has stepped in with something. Would I do this job again for someone for profit, most certainly. A minor pain, but not the worst thing I have done. The GMC Acadia with the 3.6 is similar in design and much less fun, but parts are cheaper.

 

 

View attachment 17789
View attachment 17798
View attachment 17796
View attachment 17797
View attachment 17795
View attachment 17793
View attachment 17794
View attachment 17792
View attachment 17791
View attachment 17790

You sir are a TRUE mechanic! That's good stuff.

 

 

Nice! Thank you for taking the time for this.

Being a GA car had to help some. Myself living in Buffalo, you'd need a flame hatchet for the exhaust bolts, etc. and I've been fluid filming the underbelly of the beast for years.

I also didn't realize this engine uses a single timing chain, unlike domestics like the Dodge/Chrysler/Jeep Pentastar 3.6L that has like 4-5 separate chains. If any one of them go too far out of tolerance, it's done for.

 

I have a 2017 that is at the same point with the timing chain, no one in my area (Kentucky) seems to have any confidence on replacing it. Are you anywhere between KY and AL (I go there for work often)? I'm curious what your price would be to do your thing. Local shop basically said I should retire the car, but I'm not ready to buy something new right now.

 

I live on the east side of Georgia on the coast. I could definitely do the work but we can talk pricing and time schedule direct. Understand I had to buy all timing stuff OEM there were no kits available when I purchased earlier this year but I’m sure I could do it for less than half the cost of a used engine. Be aware when the noise became constant in my case, the chain was slapping and wearing away at timing cover. I would say it wasn’t long until it either jumped time or spun a bearing due to aluminum debris floating in the oil. I wouldn’t drive it much if at all if that is your case. They’re around $7000 my way for a used engine.

 

Where did you buy the timing parts? I'm replacing just the main timing chain, tensioner and guides and probably water pump while i'm in there.

 

To be honest, at the time I couldn’t find anything beyond OEM and that’s exactly what I replaced as well. Cam chains were fine. Also front gasket seals and the variable cam actuator seals.

 

I see a kit on z1 off-road, it comes with all gears, tensioners and chains for about 1200$. Does this sound about right? I havnt seen any other kits for sale and was shocked by the price so I want to be sure I’m not missing something. Obviously I’ll need all gaskets and o rings as well.

 

I hope to do this soon, since I am having the same issues everyone else is having with their 2017. I am skilled enough, and competent enough, to do the repairs on my own. By that, I mean I can take things apart and put them back together with no problems. However, timing chains freak me out. Without access to any repair manuals, how do I ensure that the timing is still correct when I take the old chain off and put the new one on? As long as nothing rotates should I be good? From your write up it sounds like I can take it apart and put it back together without having to do anything but turn the car on when I'm done, is that correct?

 

Hey that’s crazy my car is a 2018 it’s been sitting now for 6 months I spent around 2,000$ still don’t know what is going on just smoke and noise last guy said it needs engine another one said it’s the chain I’m confused

 

Excellent write-up Jason! Very helpful.

As you say there is very little good info on this engine online. To keep the information together, I'll add my experience here.

My 2017 Pathfinder would not start. VQ35DD engine. History was unknown. No spark and no fuel at the cylinders. 179,000 km on the odometer. By accident I found the engine ran after a very long crank when the bank 2 exh. cam position sensor was disconnected. The timing chain was very noisy.

I used a PicoScope to verify the crank to intake cams relationship. The results did not match the pattern shown for the VQ35DE Nissan field service manual. I checked a 2020 Pathfinder with the VQ35DD engine and it was similar to mine. The FSM for this DD version does NOT show cam/crank waveforms.

The sensors are fed +5volts and ground. The output is normally +5volts but goes to ground when a tooth or sprocket is encountered. The crank has 18 teeth, a gap of 2 teeth, 18 more teeth, another gap of 2, another 18 teeth and a final gap of 2. With the teeth 6 deg. apart, 18 teeth and a gap is 120 deg. Two more patterns are a full crank rotation. Two crank rotations are required for one cam rotation. So basically, 6 groups of 18 teeth with gaps for one complete combustion cycle.

The intake cams have 3 pulses per rotation. (120deg apart) Bank2 is 60 deg after bank1. The overall effect is that there are cam pulses from alternate cams every 120 crank degrees. They indicate an approximate TDC for each of the 6 cylinders.
(EDIT: Subsequent info shows the crank gap coincides with BDC. See later post.)

The good 2020 engine had the cam pulses aligned with the crank gaps. My engine had the bank 2 timing about 10 deg. early. I suspected the bank 2 intake cam phaser to be stuck in an advanced position. The timing cover needed to come off.

My Pathfinder was AWD and the original write-up was on an FWD. I wasn't sure removal out the top was possible so I opted for in-vehicle cover removal. It can be done. It's ugly and Nissan's FSM is not very accurate in this matter.

Once inside, I found the chain extremely loose and the bank 2 intake cam sprocket/timing chain marks off 1 tooth. Exactly what Jason had discovered and more. But on moving the cam slightly, the tensioner took up the slack immediately and looked normal and tight albeit one tooth off.

The problem ended up being the tensioner itself. There is a ratcheting mechanism that prevents the piston from retracting back into the bore once it has been extended. The teeth on the ratcheting pawl were worn off or broken. I could push the piston back in with only moderate thumb pressure. A new one is solid with no reverse movement whatsoever. I could have easily replaced the chain and guides, put it back together then have the same problem in the future.

 

You made it look pretty easy, the front coming off is a back saver I bet

 

That is an excellent diag and great information @just_bob.

This is alarming to me to hear of these issues with only 111K miles (179K kilometers) on the engine. I'm not sure maintenance alone will prevent this type of failure and shop costs to fix it (if you could even find one to do it) would be astronomical. To the point these vehicles will just be junked.

 

Here are some screenshots of waveforms. This was sufficient for my purposes. However, you may notice there is not enough info to determine specific cylinder numbers. Typically, an extra pulse or something is needed to identify cylinder 1 TDC so the ECU can deal with the correct injector and spark at the correct times. If one needed to diagnose no starts or long cranks this additional info would be useful. If anyone has any insight on this, feel free to comment. The FSM wasn't helpful.
(Sorry for the poor quality of the screenshots. I couldn't find a better way of inserting the very clear PicoScope software images. But I think the basic info is there.)

 

A question for Jason:
Would you happen to have the part number for the front cover lower seal? I was given part # 11121-7Y000. Unused it appears thicker than the used original and the online parts manuals say it works on both the DE and DD engines. I have my doubts.

Edit: 11121-7Y000 is CORRECT. Some Nissan online parts lists incorrectly have the front and rear upper pan seals reversed. (#11121-7Y010 is for the flywheel end and is 1/2 to 1 inch longer.)

 

Just to add to the above info, here's a cool video showing the timing marks on a 2017 VQ35DD along with showing the wear items that were replaced.

 

At the very end of the video, he easily pushes the old tensioner piston back into the bore with little effort. That should NOT be possible!!! The ratcheting pawl is broken or worn out.

 

Found this in the FSM showing the exhaust cam position pulses. The double pulses and pulse spacing would give the ECU enough info to determine where each cylinder is.

 

Man if it weren’t for this post I wouldn’t have the confidence to do the project. Thanks for the info and all the pictures, I just started opening my wife’s car today. Same deal, chain slapping sound at idle and low rpm, cam position sensor is firing, it had sludge buildup throughout the engine, clogging up my valve covers and messing with my pcv system. These engines don’t seem to vent properly.

 

What year and how many miles on it? Also.. for the sake of data collection, how often were oil changes done on it?

I hear you on these particular VQ35DD engines not venting properly, but they defy any logic I can come up with in terms of why they blacken and sludge the engine oil the way they do.

You figure with a bad PCV system, you get visible moisture build-up somewhere, like oily mayonnaise build-up on the fill cap, PCV plumbing or dipstick. You don't see any of that with these.

If it was fuel dilution, the oil level would increase. You don't see that.

Super high oil temps. You don't see that either.

I'm so paranoid with my 2019 that I change the oil / filter every 3000-3500 miles. Usually closer to 3300. I rarely use the recommended 0w20 and use 5w20, 5w30 or I've even used 10w30 w/ no issues of any kind.