2008 Burning Oil?

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Cr@2y Gr33k
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2008 Burning Oil?

Postby Cr@2y Gr33k » Mon Dec 02, 2013 9:51 pm

Hello everyone, it's been a while since I've posted on this forum. I'm having a little issue with the VQ40 burning oil. My 08 has a little over 88,000 miles. For some reason a few weeks ago, the engine sounded like it was short on oil. I was afraid I was going to some irreparable harm so I left it at the dealer. After the tech at the dealer looked at it, they told me that I was down THREE quarts of oil, and that the engine is burning oil. I would like to know if anyone else has experienced an issue like this or is experiencing an issue like this, and how costly or how easy will this be to repair. The last thing I want to do is get rid of the Pathfinder after it's been paid off for over a year.


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smj999smj
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Postby smj999smj » Mon Dec 02, 2013 10:42 pm

That usually a bad sign. Assuming the engine hasn't been neglected as far as oil changes, the first thing to check would be the PCV system. The PCV is on the right bank valve cover. Make sure the valve is not stuck and the hose is connected and not collapsed. A PCV issue would be the best case scenario, as it is cheap and easy to fix. The other two issues that sometimes arise on these engines usually require replacement of the engine.
The VQ40DE does not use a conventional EGR valve-type system. Rather, it uses the variable camshaft timing to crack open the exhaust valves slightly during an intake stroke to accomplish exhaust gas recirculation. As the exhaust valve is opened during the intake stroke, exhaust gas is pulled directly from the exhaust system, past the exhaust valve and into the combustion chamber, where is mixes with the fresh air that passes by the intake valve into the combustion chamber. As many Altima 2.5L owners know, this can lead to problems if the catalytic converter starts to break down. What happens is that particles of the catalytic converter substrate get sucked into the combustion chamber along with the exhaust gas and the score the cylinder walls until they create a poor sealing condition between the cylinder walls and the piston rings. The fix is replacing one or both of the upstream catalytic converters and replacing the engine or short-block assy., or overhauling the engine. Used VQ40DE engines usually show up on Ebay for around $2500.
The other issue with VQ-engines is something I think doesn't affect the 4.0L and is more of a problem with the earlier Pathfinders with the VQ35DE engine. The VQ engines apparently have a very slight taper to the cylinder bores. The oil control rings would stick in the piston grooves and not seal during the full stroke of the piston and cause an oil burning issue. From what I understand, Nissan re-designed the ring set to prevent this from happening. The problem, of course, is that you need to teardown the entire engine to re-ring it. I doubt that this is your problem because I believe this issue was addressed before the VQ40DE production.
Leaking valve seals could cause oil burning, but I haven't heard of any cases of bad valve seals on VQ-series engines. If the PCV system is working, then a compression test would be in order...and cylinder leakdown test, if needed.

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Postby skinny2 » Tue Dec 03, 2013 6:23 am

I love how the dealers diagnosis is "3 qt low...burning oil". Allllllrightythen!

I'm not sure I've seen anyone on these forums complaining about oil burn or loss. I'm over 100k on my '08 and i'm down maybe 1/4 qt @ 9,000 mile interval on oil change. I'm starting to sample at every oil change though to monitor any jumps in wear.

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Postby disallow » Tue Dec 03, 2013 6:49 am

That was a great summary SMJ.

I agree, this is bad news. My experience is that the dealer will take this diagnosis and suggest an engine replacement. Chasing and attempting to repair oil consumption issues can be costly, and may outweigh the cost of getting a certified recon engine, especially considering the hourly rate that most stealers charge.

Ran into this on my sister's 99 civic when she snapped the timing belt. Ended up taking it to a friend that does competent repairs in his own shop. That may or may not be a good idea in this case, it would depend on how much you can get a recon engine for.

I also recall Carl having the issue regarding the Catalyst substrate getting sucked into his cylinders. That makes me worry for my 05, I've had a P0430 code for a while now...

Here is Carl's post:

http://www.thenissanpath.com/viewtopic. ... ght=#40663

t

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Postby Cr@2y Gr33k » Tue Dec 03, 2013 7:17 am

Wow. Thanks for the replies. I knew it had something to do with the cats. Last winter, one of the cats had gone bad and i had to have it replaced along with new ignition coils and spark plugs. It's been losing/burning oil since then. I will have to keep a close eye on it now.

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Postby skinny2 » Tue Dec 03, 2013 8:07 am

It seems like bad cats are somewhat common on these as well. Any idea what causes this particularly at such low mileage. I don't recall having a bad cat on ANY vehicle and I've owned several well into the 200k mile range.

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Postby slavabon » Tue Dec 03, 2013 8:04 pm

Apparently a lot of FX45s burn oil as well and a good fix for it was using Shells Rotella t6 5w40 oil. Most people report an end to oil consumption with this oil, but you can google all the views if you like. I'm not sur how bad it eats oil in your case, but this is worth a shot before you start ripping your engine apart. It's a good, inexpensive synthetic oil anyways that can be purchased at any Wallmart.

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Postby Cr@2y Gr33k » Wed Dec 04, 2013 8:05 am

Since I had taken the Pathfinder to the dealer, I have been checking the oil regularly. Every time I check it, there is no loss of oil. Not yet anyway. Does it have something to do with the fact that I changed from conventional to synthetic oil? The service manager told me that it shouldn't make a difference. I know that synthetic oil is thinner than the convetional 5w-30 that I usually put in.

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eieio
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Postby eieio » Wed Dec 04, 2013 8:56 am

three qts low is a LOT OF LOW! :(
that in itself is plenty to cause engine wear grief
didn't you check the oil level when (or before) the engine got noisey? :?
for now, you're doing the right thing by monitoring the level
is it possible that they (the dealer) were just plain wrong (or dishonest) about the oil level being so low?
then again, there's the noise
is it gone since the dealer visit?

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Cr@2y Gr33k
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Postby Cr@2y Gr33k » Wed Dec 04, 2013 2:06 pm

Before that I checked it a few times. When I would pull the dipstick, it showed that there wasn't any missing oil. Since the dealer visit, there has not been any noise. As for the dealer being wrong or dishonest, I don't know. I have a mechanic that I trust, that I will be taking it to. He had rebuilt his brother-in-law's Pathfinder's engine.

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Postby skinny2 » Wed Dec 04, 2013 8:01 pm

Cr@2y Gr33k wrote:Before that I checked it a few times. When I would pull the dipstick, it showed that there wasn't any missing oil. Since the dealer visit, there has not been any noise. As for the dealer being wrong or dishonest, I don't know. I have a mechanic that I trust, that I will be taking it to. He had rebuilt his brother-in-law's Pathfinder's engine.
Who did the last change and how long since before the noise appeared? I wonder if it was underfilled by a couple quarts which maybe caused issues and burned off even more.

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Cr@2y Gr33k
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Postby Cr@2y Gr33k » Thu Dec 05, 2013 6:44 am

I always have gone to the dealer where I bought my Path from to do oil changes. It's convenient because it is on the way to work. Just drop it off or wait for the oil change to finish, as they are usually no more than 30 minutes. The last time I changed the oil was about two months ago. I started hearing the noise two weeks ago, and went immediately back to the dealer to have it looked at.

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Postby Cr@2y Gr33k » Sat Jan 11, 2014 6:52 am

After a lot of thinking and deliberation with family and friends, I finally decided this week to trade the 08 in. I am now the owner of a 2011 Pathfinder LE. I love the color and all of the options that it has.

Image[/img]

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Postby smj999smj » Sat Jan 11, 2014 3:20 pm

Well, that's one way to solve your problem!

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Cr@2y Gr33k
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Postby Cr@2y Gr33k » Sat Jan 11, 2014 6:38 pm

I weighed my options and talked with my mechanic. He told me not to bother overhauling or replacing the engine. So I did the best thing. i bought the 11 with a 100,000 mile warranty.


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