[ap.higgs]

I'm curious what this job rates on the PITA scale 1 - 10... after reading the Haynes manual seems like a solid 8/10 PITA. Maybe more!?
If you're curious why I'm asking.. read on.

Here's my story in three parts:

PROLOGUE
-2008 Nismo, obviously the VQ40. 282000 km. Owned since 2017.

Current relevant OBDII codes:
-P0011 - Camshaft timing position over-advanced
-P2A00 - Bank 1 O2 Sensor 1 Above threshold
-P0300 - random misfire
-P0306 - cylinder 6 Misfire

PART 1 - 91 Octane Life

p0011 and p2A00 have been faithful friends for several years. Swapped the Cam/Crank sensors, nada. The codes don't seem to impact overall vehicle performance, but over time I've begun to wonder if they are connected to an issue I've had since purchase.. pre-ignition 'ping'. When the weather is warm and I run 87 octane fuel the engine sounds like it's full of gravel when under load - a condition remedied by running 91 (retarded ignition = proper ignition timing). Swapped for new spark plugs, cleaned MAF/intake, etc, etc, problem persists. Seems to point to a problem with the VVT/VCT system.
Confirmed that the solenoid is functioning.. perhaps loss of oil pressure in VVT/VCT system OR stuck actuator on the VVT sprocket actuator. Oh well, keep driving.

PART 2 - Timing Chain Whine / Frontier owner whine

This summer - the much-feared timing chain whine manifests! Awesome. Cool. Maybe this is an excuse to get into the timing case and check out my VVT/VCT problem..! But then after a couple months of driving the whine goes away... strange. Don't get me wrong, the engine is pretty clattery. Perhaps I just blew right through the tensioner guides.. yikes. Oh well. Still driving.

PART 3 - No heat, misfires, and stinky coolant

As the weather turned for the worse it became apparent the the truck wasn't interested in producing heat to the cabin. Only under heavy load would heat actually blow. And look! New codes! p0300 and p0306..
Burped the system, over-filled the reservoir, great - heat is back.. but man, that coolant reeks of combustion gases, and when I'm idling/running in traffic the smell starts to blow into the cabin. Oil currently appears fine, no residue in cap or on dipstick. After a month of daily driving I've still got heat, so no obvious airlocks/coolant loss yet.

SUMMARY - what would you do?
To recap: I've got a suspect VVT/VCT system, suspect timing chain tensioners, and now a suspect head gasket. Vehicle performance is not great but not bad.. rough starts, but chugs along fine once it's warmed. Fuel consumption may be up.. but hard to tell city driving in the winter - it's always seemed erratic.

What could I be missing here?
Plan of action: 1) cylinder compression/leakdown test, 2) block test (combustion gases in coolant), 3) ???

Taking the truck to a shop is out of the question, I'm a student on a tight budget. I'm interested in doing the repairs myself and have the time/shop space to do so.. BUT given the age and mileage of the vehicle, is it worth digging as deep as the head gaskets? I also have some serious work on brakes and suspension in order.
Who else has done this job?

 

[rapatt95]

Sounds like it’s about high time for a VK swap

 

[ap.higgs]

Sounds like it’s about high time for a VK swap

this can't seriously be the best option..

 

[CT_Nismo]

What you have is a project truck. Or an endless money pit. The head gasket is a priority as you are losing compression. The other codes are also no picnic.

 

[speed demon]

Head gaskets on these are not easy, if you have moderate mechanical skills, expect to spend 20-30 solid hours on it. More if you're not familiar with the Nissan timing chain and torque angle process

 

[rapatt95]

this can't seriously be the best option..

Like others have said, head gasket is a time consuming and difficult job. Is a VK swap the best option? Maybe, maybe not. But a lot of people have replaced an engine or bought a new vehicle due to a blown head gasket. Considering time, price, and typical options, you’re going to have to weigh what you can do. You said you’ve tried several things that have not actually fixed the problem. At a certain point, replacing the entire engine starts looking more appealing to get rid of the problem altogether. Whatever you decide, I do wish you the best of luck, as it sounds like you really like your truck. I know that if down the road, my engine gives up, I’ll VK swap. I do admit though, it is a bit of an extreme option

 

[TWX]

I did head gaskets on a 2.4L in a Dodge Stratus. Screwed it up. Had to have a mechanic fix the car.

 

[FrontEar808]

I replaced my head gaskets engine in vehicle; to be honest it was a 9 out of 10 PITA at the time. I basically lived in the bay for two to three weeks 8 hours a day (job offer fell through at that time). Given, one, it was my first time doing head gaskets ever, also I was solo. Two, I bought the truck with the bad head gasket(s) so I expected to have to do it when the blue devil wore off lol.
Three, best precursor to where I’m at now as a Technician, sweet serendipity😊.. enough about me.
It really depends on your situation on how soon you need it “driveable” again.
Timing chains, guides and water pump should be changed at 150k mi.
Do you have the resources to have a leak down test and block test done? If so test and verify.
There’s still some variables of what could be going on I.e. spark plug tube seals drowning your plugs creating a misfire. I’d say check what you can that would just cost you some time. Pull plugs “read them”; dip a long extension in the cylinders to see if there’s coolant or oil in there. There are peep holes on the cover to check timing as it may be off from the slack. Also don’t forget to find try to hunt down the cause of any overheat. Maybe a fan clutch gone bad.