Loud Clatter from Valve Train - Broken QX4

[drj9000]

My 01 QX4 started making a loud clatter from the valve train and started missing with the check engine light flashing. I was going up a long grade in the mountains when it happened. It was still running but with a loud clatter that increased with rpm. Oil level was good and engine temp was OK. 240 thousand kilometers on he clock.
I had i towed to a shop in he nearest town, but have no idea what it could be other than cam or valve related.

[Camelfilter]

?power valve screw(s) fell out?

[Chuck Tribolet]

If the SES light was on, what were the codes?

Automatic or stick (sticks don't have a power valve).

Chuck

[Towncivilian]

Sounds like a power valve screw assuming you have an auto transmission. These are the power valves under the upper intake manifold:



Take the UIM off (guide here) and make sure all 12 are there. If they are, apply red threadlocker to all of them; if one or more are missing, then that is your most likely cause of the clatter and other potential damage.

If it is truly a power valve screw, this unfortunately makes the third or fourth QX4 with a power valve screw related issue in the past 6 months or so. It's a little odd that all have been QX4s and not Pathfinders.

[CanuckQx4]

think how many hundreds of people that arent on this forum that have this power valve failure happen to them

So glad I openned my manifold up before it happened to me

[drj9000]

Fixed.

2 loose spark plugs. Apparently they were not tightened to the proper torque the last time they were replaced. Had all 6 replaced for $400 CDN. (scoped, plus 2 hours labour)

Big relief, I have to say...

Thanks for the input.

[Towncivilian]

What a simple fix! I'm glad you haven't suffered any lasting damage. You may want to look into having threadlocker applied to the power valve screws preemptively.

[CanuckQx4]

A loose spark plug doesnt create a loud clatter that resembles the valvetrain as you said tho...