The Nissan Path

I replaced the heads on my 06 Pathfinder with reman heads. It's been running great for the last thousand miles. No noise. Peppy and smooth.

I was sitting at a stop light this morning and this noise started. Any guesses what this might be, besides another tear down? It took me two months for the last tear down because of severe arthritis in my hands. I work for a day or two then have to let the pain subside for a few days then work some more.

https://photos.app.goo.gl/1SDLRoTarBhTh5c38

My impression is that the noise is coming from the front engine cover area, maybe something left loose (tensioner system, cam sprocket..............).
A mechanic stethoscope may be useful to track it down further.

Thanks. I'll look at that.

You were right, eieio. The main timing chain tensioner failed. It only has a thousand miles on it. When I pulled the cover, everything looked fine. When I started to turn the crank, the tensioner just collapsed all the way down to nothing. The cams were just flipping forward when it hit the backside of the lobes. I got it around to where the cams were at the timing marks. The cams were still in sync with each other but the crank was about five links off. I'm going to pull the spark plugs out and scope them to see if there is any damage to the pistons. I'm afraid of what I'm going to find. Wish me luck.

Twospeed wrote:You were right, eieio. The main timing chain tensioner failed. It only has a thousand miles on it. When I pulled the cover, everything looked fine. When I started to turn the crank, the tensioner just collapsed all the way down to nothing. The cams were just flipping forward when it hit the backside of the lobes. I got it around to where the cams were at the timing marks. The cams were still in sync with each other but the crank was about five links off. I'm going to pull the spark plugs out and scope them to see if there is any damage to the pistons. I'm afraid of what I'm going to find. Wish me luck.

Best of luck Twospeed.
Let us know what you find.

Based on my latest adventures with cam timing...

The cams with VVT are made to go plus or minus 40 degrees out of phase with their TDC position. Even if the engine is an interference design for valves that's a lot. You are probably ok on cylinder internals.

One of my camshafts wasn't advancing or retarding at all for who knows how long and the ECU barely noticed.

I scoped the cylinders and they look fine. I think the tensioner failure was actually caused by the main timing chain tensioner guide. I didn't notice it when I initially installed it but the guide has a little bit of a twist. When I installed the new tensioner, it didn't set flat against the guide. The old tensioner left half moon marks on the guide where it was slapping against the tensioner. That seems to have pushed the tensioner sideways and the clip on the tensioner was destroyed. All sorts of problems after that. The new guide sits flat against the tensioner. Nissan agreed that it was a defective part and replaced both of them. Now I just have to fish the clip pieces out of the oil pan (I have a really strong magnet I'm going to use) and then put it all back together and start it up.

It's all back together and everything seems fine. I've been driving it for a few days now. It's running smoothly. The knock is gone. No extra noises. It's peppy, but it always has been. That's why I keep it. I think I got lucky.

Great outcome!!!
Congrats!
Show us some pics of your die sometime !