Patient is a 2001 QX4.

Several years ago (!) something broke loose in my friends QX4 and banged around the engine for a few days, and ultimately dropped down into the pan. She's been driving it ever since.

Engine code P1140 is active, leading me to believe something assocuated with the Variable Cam timing broke off and fell through.

Any Ideas?

to NICO!

I can't imagine what that would break loose and bang around in an engine without causing it to lock up - but I'm not super-familiar with that particular engine. Maybe someone else will come along with a better idea?

Heath

Meridith you win the award for most interesting first post of the week.

Welcome to the group.

Your patient has a grim prognosis.

That code is associated with a lack of oil pressure, it is detected by the computer as a failure to advance the intake cam timing when commanded.

The Pathfinder and QX4 perform poorly when not maintained properly. I would start by checking for an oil change sticker and then the oil level.

The plot thickens.. or thins as the case may be..
Oil level was normal, but it was due for a change.
She takes it to her local dealer, and without asking, they replace with synthetic, after 150K on dino oil.
It immediately starts smoking and burning oil like crazy.
She takes it back a day later, and has them replace filter and oil, this time with 15-40 dino diesel oil.
Still smoking but not as much.
What would make the oil pressure drop on one bank?
Does anyone have an exploded view, or better yet, pictures of the head opened up to show the advance assembly?
Could that be what broke off and flew around the engine?
Does the P1140 code point to the drivers side as the culprit?
Regards,
Mark

I have a client with a Qby4 with 240k+ now and he switched to full syn at about 180k. That would not cause the engine to smoke. I would probably go with with 10-40 dino. Diesel oil tends to have additives in that may damage a normal engines' oil seals. I don't really know that it would have much of an impact.

I am very skeptical about this and I do not know if the damage is in the head. If I had to point somewhere first I would be looking at the timing chain area, but it has a buck fifty so there could be several problems.

How due or overdue was the oil change?

You need to get this truck some help from a specialist.
What did the dealer say about the noise/CEL?

Local Nissan dealer (York, PA) was clueless, suggested a new engine. No Infinity dealers in the area.
Dealer didn't pull codes, they were pulled at Advance Auto.
Owner is working out of state, and truck is only driven occasionally once or twice a month.

I agree that its probably in the timing chain area, assuming rail(s) or advance mechanism.

That's why I'm asking about exploded view or photo details.
Could you please point me in the direction of illustrations or photos?

Looking for failure mode / replacement info on timing solenoid, but couldn't find anything of value in searches on this site so far. Have they been known to come loose, come off? If they are controlled by oil pressure, could it be loose / off and flooding one bank with oil, overwhelming the valve seals?
Thanks,
Mark

http://www.nicoclub.com/FSM/pathfinder/ ... der/em.pdf

Here is the mechanical breakdown of the engine.

It sounds like there has been a long term lack of oil pressure causing failure or wear on something. Could be the chains could be the head...

Good Luck with the hunt.

From what I've been reading, it could be (at least) the cam sensor as that seems to be a common failure point, but given the fact that something came loose and bounced around the head / timing chain area then dropped down.. I'm thinking a piece of one of the guides, or possibly one of the solenoids. The exploded view seems to indicate the solenoid is held by a single bolt, and if that comes loose or off, it would be full on oil leak inside the head, which would lower the oil pressure..
Nothing left to do but pull it apart.

Are just going in hunting or are you planning on replacing anything?

First step is to find out what broke off or came off, so its a hunting expidition.
I'm open to hearing what you would suggest should be replaced "while we're there".

I really don't know it is very dependent on how bad it looks once you get in there.

The description is far to vague to give you an direction to head in conclusively. I'd start with the valve covers since they are much easier than getting the timing cover off. But it doesn't sound like you have much of an idea of where the noise came from...if there was something broken you should be able to tell but there is a good chance you could get in there to see nothing wrong.

It's a real crap shoot.

P1140 is passenger side cam sensor. The part is highlighted in red.




I replaced both of mine a few months ago.