Good news: I found a great '08 LE V8 with only 105K on it for an almost "too good to be true" deal. I went through it with as fine tooth comb as I could at the time and found it didn't need much aside from a front diff seal, a set of shocks, and the middle seat cup holder. Deal was good enough that even if I found a few other misc things after driving it the 3hr trip home, I'd be able to take care of it and still be good.

On the drive home, the truck performed swimmingly and I was super happy. About an hour after I parked it from the homeward trip, my boys wanted to take a spin. When I fired it back up, a nice cloud of oil smoke appeared. My heart sank.

It continues to do this. After the initial start up, the cloud creation goes away, so I'm inclined to think the valve stem seals are shot and weeping oil letting it collect in the cylinders as it sits.

I am planning on running a compression test tomorrow to make sure I don't have wasted rings. Is there anything special about running a compression test on this truck? I only have a standard compression tester from my days of wrenching almost 20 years ago

Has anyone replaced the valve stem seals on one of these before? I've done a bit of digging here and haven't come up with any step by steps. I have to do some more research on pulling the cams to get at them, and to be honest, I'm a bit terrified to do so...

Could I be missing a simpler cause of the oil burning? What I'm really afraid of is how/why it got to this point at 105K miles... I fear gross neglect and what more might crop up in the future.

It wouldn't hurt to check your PCV valve and do a fuel pressure leak-down test, first. Compression test is the same as any other engine and a cylinder leak-down test would be a good idea, as well. I would also make sure the engine oil isn't overfilled.
I'm pretty sure the valvetrain is similar to the VQ40's and, if so, would be a real pain in the tail to replace the valve stem seals! You would have to remove the front cover, timing chains, valve covers, camshafts and bucket tappets (don't mix them up) to get to the valves. It's a pretty big project!

I am planning on replacing the PCV, although I feel the cloud of smoke is way greater than what a faulty valve could potentially cause. The oil is not over full, as I've been checking it regularly to gauge how much I've been burning. So far, about 1/2 quart over 750 miles.

I didn't think about doing a leak down test on the fuel system, as I don't have any black smoke or hard starts, but it's definitely a good idea.

I know the job is labor intensive, and I'm not afraid to get into it, I'd just feel a whole lot more comfortable doing it after reading through someone else's experience.

Piston ring & cylinder wall damage may be damaged by current or prior front catalytic converter failure.
Check cylinder compression & leakdown.

WestMIPath wrote:. So far, about 1/2 quart over 750 miles.
.

While this is more than these engines would normally do it still works out to 1 qt over 1500 miles.
well within acceptable range by yesteryear standards.

VQ37s were known for this issue when Nissan went with looser rings in the horsepower wars of the late 2000s.

Not Poo-pooing your concerns but just putting things in perspective.
Your leakdown tests may yet come out fine..

palmerwmd wrote:

WestMIPath wrote:. So far, about 1/2 quart over 750 miles.
.

While this is more than these engines would normally do it still works out to 1 qt over 1500 miles.
well within acceptable range by yesteryear standards.

VQ37s were known for this issue when Nissan went with looser rings in the horsepower wars of the late 2000s.

Not Poo-pooing your concerns but just putting things in perspective.
Your leakdown tests may yet come out fine..

My 2013 5.0 V8 Mustang GT will use about a quart every 1,500 miles and has since new. I thought it was an issue until I learned that the 5.0 in the Mustang has what Ford calls a floating ring? And it's not uncommon for the V8 to use some oil esp if you wind it up around town. It will hardly use any oil if I drive it all highway miles. Strangely it will use less Valvoline Synpower synthetic then several other oil brands I have tried.

So, I'm finally getting time to get back into this. I did do a compression test, and all cylinders are hitting between 170 and 180 psi. I don't have the tools (or knowledge) to do a fuel system leak down test though.

When pulling the plugs, the 1 and 3 plugs were by far loaded up the worst. You can see them from the link below.

https://drive.google.com/open?id=1nk7mL ... Yn_GQRR_Ob

Next thing I did was pull the driver's valve cover gasket off to find a nice build up of sludge, the biggest of the build up being at the 1 and 3 cylinders. You can see that loveliness here:

https://drive.google.com/open?id=1XJuHX ... oER46SZdr2

https://drive.google.com/open?id=1ytHZn ... FvsqNhzGdk

My plan at this point is to pull the other valve cover, clean out as much of the crud as I can, unblock any and all oil passageways, and put it back together. I think I'll run a few short millage oil changes, substituting a quart or two for trans fluid to help clean things out. I've contemplated running some sort of engine clean through, but I'm skeptical based on the horror stories of ruined seals and burned up bearings... After all is said and done, I'll drop the pan (which I haven't looked into seeing how bad of a job that is yet) to desludge and make sure the oil pump pickup screen isn't getting all plugged up. Oh joy.

Took advantage of the warmer weather and put the pathy back together over the past few nights. I ended up dropping the oil pan too, just to see how bad things were. Good thing I did, the oil pickup screen was 75% plugged and there was a healthy layer of sludge deposit. You can see for yourself here:

https://drive.google.com/file/d/1K-Y1ya ... sp=sharing

Note that the oil left in the pan has about 500 miles on it.

I did swap out a quart of oil for trans fluid and am planning on changing the oil again in less than 500 miles. When looking under the truck after firing it back up, I also noticed a small leak from behind the oil cooler plate. So it looks like I'll be replacing the seal behind that at the next oil change too.

After firing it up, I let it get up to operating temp and took it for a spin around my neighborhood, then parked it. After letting it cool down for a half hour, I restarted it. This is when I would typically see a big cloud of smoke from the tailpipe. Not even a small puff this time. It looks like clearing the blocked oil passages in the head helped keep the oil from pooling up top and seeping down the valves. Time will tell though...

Wow! So bad PCV, coolant mixing with the oil? Or neglect from past owner? Anyway it sounds like your cleaning plans should fix the problem over time. Run your cleaner mixed with oil like trans fluid or some say Marvel Mystery oil works too and make a few highway runs should clean up.

PCV was completely plugged up, but it was mostly just neglect from what I can tell at this point. The carfax report listed oil changes every 20,000 miles or so. I just assumed they were taking it to different garages that don't all report to carfax when they do service. Assuming bites me it the arse again...

Good job running down the problem!

Carfax reports can be very spotty when it comes to oil changes and I think your expectation may not have been unreasonable.

For example my favorite shop does not report to carfax so tons of maintenance I do is unreported.

Those compression numbers sound great!
I suspect the engine should give you many years of good service!

If it was not hard to drop the oil pan I think after several short oil change cleaning runs I would drop it again and do a full clean out.

When I picked up a new oil pan (bent the flange pretty severely pulling the old one.), I picked up two gaskets for just that reason

Been driving the Pathfinder all week with zero oil loss per constant dipstick checks and zero signs of burning. This makes me very happy. After 200ish miles, the oil is already darkening though, so I may do the next oil change tomorrow.

On a side note, I absolutely LOVE driving this in Michigan winters. AWD with the traction control turned off is phenomenal with the V8.

WestMIPath wrote: On a side note, I absolutely LOVE driving this in Michigan winters. AWD with the traction control turned off is phenomenal with the V8.

PICS!