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Discussion Starter · #1 · (Edited)
Will update as I go along.

A/Cs been acting up. Noticed some residue under the battery tray, checked it out and looks to be a hairline leak. I ordered a new "H" line and will be replacing it this weekend.

Oil gets dirty and thin fast, and smell of fuel in the exhaust. Tried oil stabilizer to see if I could extend the oil change to at least 2500 miles. Looked promising in the beginning. Got to 1500 miles, looked good, got to 2k and the strong smell of fuel showed back up. When I first change the oil the fuel smell in the exhaust is not as obvious but when the oil is dirty the fuel smell comes back. I change my oil about every 1500 miles or so before trying the stabilizer and hoped that the stabilizer could extend that to 2500 miles but seems not. Fuel smell came back at 2k with stabilizer (better than without) so I decided to change the oil as it was looking thinner on the dipstick, and on the paper towel too. Found metal shavings from the filter side and decided to down it until I get a chance to check it out.

Released fuel pressure, to work my way to replace the injectors. I'm hoping that would resolve the fuel smell in the exhaust. I didn't have a CEL prior to starting this process. I pulled the plugs and they have carbon and white powder, the outside of the coil boot had a little oil on it (I'm guessing it's from touching the wall on the way out). Used a borescope camera that I rented from AutoZone and nothing stood out on the pistons, the camera quality wasn't too good so hopefully nothing crazy is there because I couldn't really see too much. Did a compression test. Started on the passenger side and was reading 195, I noticed that I didn't plug my VVEL actuator back and redid it (hopefully I didn't mess anything up worst than it already is). Started from the beginning and highest was 220 and lowest was 200. The manual says the difference should be 14 between cylinders and I'm above that. So going to move on and make my way to the injectors and cleaning the intake valves. I did notice that there was rtv between the rocker cover and where the spark plug well meet(according to the gasket pictures online and the repair manual, this should be a gasket. Alright, that's all I have for now and will be back as I get stuff done.

Leaking coolant. There is a line of dried up coolant going down the front cover. I thought it was a leak in one of the lines but looks like it might be the water pump. Will be checking it after cleaning the intake valves.
 

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The differential limit between the cylinders, regarding compression is 14 psi. Anything higher and it could be indicators of piston rings wearing out. Also, some 2011-2013 QX56s were plagued with the timing chain/oil jet issues that Infiniti did recall but unfortunately expired.
 
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Discussion Starter · #3 ·
Thanks for the info. I'm hoping it's not piston rings, that's a job I'm not quite ready to jump on. My timing chain was changed around spring last year, because the valve lifter bucket broke in the middle, that was a pretty penny and hoping it's holding up.

Only had time to get the injectors out. That was some work to get the fuel rails off, had to pull the studs out with the fuel rails. Passenger side had one injector stuck in the engine side and the others came up with the fuel rail, had to pry it up/out. All the injectors came up with the fuel rail on the driver's side. Will be putting the new injectors in tomorrow. I didn't get new injector holders and will be taking a chance on re-using the old injector holders even though the manual says it should be replaced

Will probably be doing the carbon cleaning tomorrow. Hopefully the intake valves are closed, not sure how to go about making sure but crossing my fingers that the carbon isn't masking any slight openings when I start the cleaning process. There was oil coming from the intake manifold, there was enough to make a drip before wiping it up from the port areas.

Will probably check the valve lifter bucket before I put the intake manifold back on.
 

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To ensure the intake valves are closed, you have to start off with manually turning the crankshaft pulley to TDC. Once you do that, insert a long screwdriver or dowel into cylinder 1 and note the height of it. Insert it to the other cylinders, compare the height and and you'll see differences. An old school method is to leave the screwdriver or dowel in place and while turning the crankshaft pulley, you'll see the screwdriver or dowel rise up (closed) or drop down (open).

To thoroughly clean the intake manifold, spray brake cleaner, throttle body cleaner, etc into the intake ports on top of the intake manifold where the PCV hoses connect to. Also, where the MAP sensor plugs into the rear of the intake manifold. You'll also notice next to the MAP sensor location is another port that is plugged up. Remove that and spray away. There's going to be a lot more residual oil that will drain out from the intake manifold.
 

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Discussion Starter · #5 · (Edited)
Thank you very much. I wasn't able to hit it yesterday and started this morning. I didn't see this before I started and will use this method moving forward. Hopefully I'm not to far gone and nothing leaked through if it's not fully seated. It looked closed with all the carbon that's built up and I started with carb/throttle body cleaner, some scraping and only almost done with cylinder 1. The carbon on one of the two valves in cylinder 1 is breaking loose with little effort, not much for the other one. If this is the process, I think I'll be at it for a few days. My rides in a self help shop and only able to get in there a few hours at a day. Thank you for your help.

Just tried turning the crankshaft five times and no valve movement. I put a piece of tape on a long screw driver to mark cylinder one height and no noticeable difference between the other cylinders. Not sure if it's because the fuel injectors aren't installed? I'm going to press on cleaning in the meantime and do more research at night to see what could be causing the valves to stay closed
 

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@AYCHE, sorry for the confusion about turning the crankshaft. I completely forgot these VK56VD motors are VVEL operated so the intake valves are closed regardless. I just remembered when the first time I did this DIY years ago, I questioned it too and learned afterwards on why the intake AND exhaust valves stay closed at TDC.
 
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Discussion Starter · #7 ·
@AYCHE, sorry for the confusion about turning the crankshaft. I completely forgot these VK56VD motors are VVEL operated so the intake valves are closed regardless. I just remembered when the first time I did this DIY years ago, I questioned it too and learned afterwards on why the intake AND exhaust valves stay closed at TDC.
No worries. Thank you for the updated information and help.

Would the valves open through any point in a turn of the crankshaft?

Also, do you think there would be damage caused if I did the compression test with the passenger side VVEL actuator disconnected? I checked compression and three, maybe four, times before realizing that i forgot to reconnect the VVEL actuator after removing the coils and plugs.
 

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Just make sure the crankset pulley is at TDC.

I doubt you damaged anything with the VVEL disconnected. If anything, when you plug everything back in, it'll probably show a DTC for the VVEL since it was disconnected when you had the truck switched on.

Btw, this was a thread I created almost 2-1/2 years ago when I did this DIY GDI cleaning and diagnosing a stubborn P0171/P0300.

 
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Discussion Starter · #9 · (Edited)
Thank you very much for the reassurance and providing the write up.

Even with the crank at TDC, I spray a little carb cleaner at a time to double check for any possible opening/leak. The carbon is caked on and it makes it a little challenging to see clearly if there is any opening. My fingers are crossed every time I go to make sure and even when I spray the cleaner.

One day I saw coolant leaking, thought a mouse bit the line, topped it off and it hasn't leaked since (or at least haven't been able to tell). But I noticed that there was trace of coolant down the front bottom portion of the engine (while I was setting up to turn the crankshaft) and thinking my water pump is leaking. I'll be replacing that once I finish carbon cleaning.

I cleaned up all the intake valves best I could but had to push my vehicle out of the self help shop. Wasn't able to get back to it for a little while until today. I finally was able to get back and get the car back in but I messed up by holding down the brake and turning the motor over before getting it pushed back in. Eager to get back in track, I went to turn the crank to TDC by hand and no luck, it was very hard even with and extended ratchet. I had the spark plugs in, hand tight and no packs connected. I thought this would be the hang up as to why the crank wouldn't move by hand. Pulled out the spark plugs and looked in with the borescope. Looked in cylinder 2 and there was liquid, the intake cleaner got past the intake valves and was sitting on top. I stuck a vacuum hose in the spark plug well and a air blow gun in the injector spot to blow out and suck up the intake cleaner. The other cylinders looked to be dry.

I thought to bump it to see if I could get it to TDC but wouldn't. Tried again by hand and this time it made it from 1 o'clock position to 6 o'clock position. But wouldn't go further. Tried bumping again in hopes to move it to TDC and it would always pass TDC each time Went back for a last effort by hand and noticed an odd sound that wasn't the same as when I was able to turn the crank by hand before. Sounded like something was rubbing/grinding metal on metal and it felt like it gave a little when the odd sounds appeared while turning the crank. I start to look around the engine bay and my heart sinks as I see that none of my camshaft position sensors and VVEL actuators are hooked up. I've come to the point where I think I have to tear this motor apart and get to replacing who knows what. I just hope that the block itself is good and that it's not too bad. I'm good ng to start my research for rebuilding and hope to get it done right. So the journey is about to begin.
 
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