Valve Cam Brackets Broken? Chasing down the tick...

loon

Hey guys, might be long but this one has been alot for me.

Back in December after a few cold days (rare down here in FLA) I started randomly losing power, like the engine would climb rpms but there was no speed that came along with it. Thought it was MAF at first, replaced the sensors, the problem came back the next day. Cleaned the throttle bodies... the problem came back 3 days later. Changed the spark plugs, same story, came back the next day. So i determined it was heat sensitive, came back from vacation after my AHA moment realizing it was probably the fuel pump. That it was.

Changed the fuel pump and then took it up the next day to Sebring for a track day, on the second lap of orientation I got a fatal loss of power and ticking



Now I'm here trying to diagnose it.

Took the valve cover off and the only thing strange that I found was this:

https://imgur.com/XqPu0pu
https://imgur.com/pbu1mTJ

(Sidenote youtube was forcing me to use shorts because it's such a short video, kinda weird but w.e)

It looks like the valve cam bracket is slightly damaged where it mounts to the head. It's much worse on cylinder 1 than on 3, and 6 looks undamaged.

Additionally the VVEL linkage arm (which I can't find anywhere what to call it because NISSAN doesn't sell or identify this part individually) has way too much play, especially compared to the other two cylinders



When looking down the intakes it is clear that cylinder 1 has a significant amount more carbon buildup than any other cylinder. Images probably not necessary...

Last note, I checked codes AFTER taking the intake plenum and everything off and got P0603, P0123, P0228, P2133, P0223. But those are all overvoltages on each TP sensor + a ECU fault that could have realistically been from disconnecting the battery in a weird way.

SO... cylinder 1 is probably a problem? but I haven't has misfires since I changed out the fuel pump. The ticking doesn't sound like rod knock and I'm still technically able to drive with whatever the problem is (I was able to drive off the track, then to the front gates to be towed with no problem) of course with no power. I'm fairly confident that the problem isn't rod knock, so the only other thing MUST be the valves, and well... the furthest I've got with that is the above pictures, think that's the cause?

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Dreadnaught

You definitely have cracked cam caps or unless those parts are part of the Vvel ladder. On the last video that part your moving definitely has a lot of play. Spin the engine by hand and see if the noise happens. I'm betting that piece is your noise. But, further tear down may be required. Also, put cylinder 1 at TDC and stick a bore scope through the spark plug hole and see if the intake valves are seated.

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fryzia23

I would pull the oil pan before going crazy. If there is no metal then its a good sign the bearings are fine. To me does sound like rod knock. Also to check for rod bearing damage, you can have the piston up and stick a long screwdriver or 1/4 extension into the spark plug tube and see if you can push the piston down. If bearing is gone it will make clunk noise. I would start with #5. It seems most common and it happened to my motor.

SG4247

Looks like you need a new passenger side head assy.

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DrBacon

That slop on the VVEL cam is normal, I'm willing to bet your knock is coming from the bottom end.

loon

Went to a shop and they found a bent valve on cylinder 6 (passenger rear). Not even where the seemingly problematic cracks were. Cracks seem to be just part of casting according to them.

Does anybody know if exhaust valves are replaceable without a full tear down?

Really my last option until swapping it


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Black 2014 370z Sport Touring MT | FortuneAuto 500s | 25mm Rears 20mm Fronts | Invidia Gemini Exhaust