2002 QX4 with 102k miles. purchased it with 20k miles. seems to burn 2 quarts of oil between oil changes (3000 mile oil changes)
the truck does not show hints of burning oil at all, and it does not leak oil.
is it normal to burn oil?
Burning Oil
Re: Burning Oil
NO
If it is burning oil at the rate of 2 quts between oil changes at 3000 miles you should have some oil discharge in carbon forming around the exhaust pipe. Your EGR may also be carbon filled, your valve upper or top end may be carbon filled. Your idle air control valve may be a bit plugged. How is your mileage?
If you do not believe that the engine may be fouled with carbon, does it run on when stopped, does idle try to hunt, have you seen the plugs lately. Still concerned try Seafoaming that car. If you follow instructions you may dissappear in the fog of smoke.
If that truck is full of carbon you will over time increase compression to the point of run on. If there are no leaks that oil if not forming carbon could be part of your coolant which is also not a good thing.
All oil leaks are not readily evident, some tend to crowd the upper transmission and bell housing, mix with dirt and stay thereespecially a new leak.When you get some free time, crawl under with a bright flash light and look close, at the crank case, at the main shaft crank, at the rear of the engine and the valve covers.
Look for oil drips and drops where you park.check the forward side of the rear diff and around the transfer case and end of the transmission.
2 qts of oil are going somewhere...undercoating as it were
If it is burning oil at the rate of 2 quts between oil changes at 3000 miles you should have some oil discharge in carbon forming around the exhaust pipe. Your EGR may also be carbon filled, your valve upper or top end may be carbon filled. Your idle air control valve may be a bit plugged. How is your mileage?
If you do not believe that the engine may be fouled with carbon, does it run on when stopped, does idle try to hunt, have you seen the plugs lately. Still concerned try Seafoaming that car. If you follow instructions you may dissappear in the fog of smoke.
If that truck is full of carbon you will over time increase compression to the point of run on. If there are no leaks that oil if not forming carbon could be part of your coolant which is also not a good thing.
All oil leaks are not readily evident, some tend to crowd the upper transmission and bell housing, mix with dirt and stay thereespecially a new leak.When you get some free time, crawl under with a bright flash light and look close, at the crank case, at the main shaft crank, at the rear of the engine and the valve covers.
Look for oil drips and drops where you park.check the forward side of the rear diff and around the transfer case and end of the transmission.
2 qts of oil are going somewhere...undercoating as it were
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Towncivilian
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Re: Burning Oil
I wouldn't run a solvent such as Seafoam in the crankcase, it can potentially loosen large deposits that can clog oil passages or the oil pickup. Perhaps through a vacuum line is ok, though. 20% of the oil capacity substituted by Marvel Mystery Oil has been equated with a slow, gentle cleaning process by many members on Bob Is The Oil Guy, it may be worth trying for an oil change or two.
Perhaps your PCV valve is malfunctioning, but it's quite difficult to access and replace. Another possibility is a power valve screw falling out, being consumed by the engine, and causing engine damage which could be manifested in the form of oil consumption, but such an event happening on our VQ35DEs is a rarity. It's possible that the right hand valve cover has been clogged; read here.
What brand of oil and oil filter are you running? What is your typical oil change interval?
Perhaps your PCV valve is malfunctioning, but it's quite difficult to access and replace. Another possibility is a power valve screw falling out, being consumed by the engine, and causing engine damage which could be manifested in the form of oil consumption, but such an event happening on our VQ35DEs is a rarity. It's possible that the right hand valve cover has been clogged; read here.
What brand of oil and oil filter are you running? What is your typical oil change interval?
Re: Burning Oil
Towncivilian is right with things like Seafoam, too many guys for some reason think it is neat to see so much smoke from your exhaust pipe that the Fire Dep't gets called in.
Older cars should not be drenched with Seafoam.
But they will work well with a small amount over time and the car will not smoke. Be cautious with any cleaner as Towncivilian states, loose carbon particles will travel until they are stuck and if the stuck particle is big enough to slow or stop oil flow, good bye!
I use Seafoam rarely, I like marine 2 stroke oil in my Q and my Goldwing of 31 years. Keeps upper end lubricated and helps other areas and it is cheap and can be burned
Older cars should not be drenched with Seafoam.
But they will work well with a small amount over time and the car will not smoke. Be cautious with any cleaner as Towncivilian states, loose carbon particles will travel until they are stuck and if the stuck particle is big enough to slow or stop oil flow, good bye!
I use Seafoam rarely, I like marine 2 stroke oil in my Q and my Goldwing of 31 years. Keeps upper end lubricated and helps other areas and it is cheap and can be burned
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metalfabsteve
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Re: Burning Oil
Thats not as bad as mine burnes 5 litres of oil in 5000 kms no leaks no smoke!king_j wrote:2002 QX4 with 102k miles. purchased it with 20k miles. seems to burn 2 quarts of oil between oil changes (3000 mile oil changes)
the truck does not show hints of burning oil at all, and it does not leak oil.
is it normal to burn oil?
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Buzzman
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Re: Burning Oil
Wow, that can't be good.metalfabsteve wrote:
That's not as bad as mine. Burns 5 litres of oil in 5000 kms., no leaks, no smoke!
Where is it going if not out the tailpipe?
My '02 has over 240,000 Kms, and uses 1 litre between oil changes, which I do every 6,000-7,000 kms.
I've been running Mobil1 since I bought it in 2003.
Maybe that makes a difference?. Thoughts?
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metalfabsteve
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Re: Burning Oil
I read that the pcv valve is a flaw and it sucks oil through mine is a 5 speed so its mabey more prone to it. My 97 hardbody pick-up would use literally no oil between 5000k intervals.
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Towncivilian
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Re: Burning Oil
I don't know, my PCV valve is original as far as I know and my Pathfinder doesn't seem to consume a drop of oil. All power valve screws were tight and accounted for as well, and my parents took good care of the Pathfinder when my mother was driving it, so it's had a pretty good service history. But then again I've always changed the oil roughly every 3k miles... this time I'll extend it to 6 or 7k (why waste some good Mobil 1 High Mileage oil?) and see if any gets consumed - but I doubt any will.
Re: Burning Oil
1997 QX4 at 240,000 Km with Mobil 1 not a drop, change out is from 4-6 months.
PCV vent keeps the crankcase from building excessive pressure and then redirects to the intake as does EGR with the hope of burning off the oily excess.
Verify your by pass at idle around the throttle plate with your idle control circuit, look closely at the valve for carbon. Check the throttle plate for carbon build up and pull at least 1 plug and see what colour it is, a #3 or 4 since it is mid block.
3 -5 liters or quarts within an interval of change at about 5000 miles is about a quart per 1000 miles. A too high consumption with theses engines. It may do you well to do a leak down test then a compression test just to see if valves and rings are wearing. An engine will still run with low compression and blow by but you exhaust parts especially the cat will take its toll. Converters do not wear out, they are killed and a loss of 3-5 quarts is quite a lot for a converter to digest.
If your still sure there are no leaks, you can put a filter cloth in or wrap around the final exhaust port in the tail end where the pipe is not too hot, a cloth filter should withstand 452F and the tail pipe at the very end is not that hot. An experiment with a oily filter would show you if you are running that much oil through the engine.
I know that I run no appreciable amount of oil loss and my tail pipe has a black appearance and my throttle plate and intake need 2x a year cleaning, with 3-5 quarts consumed are you guys getting a very dirty throttle and /or dirty intake? Maybe you would like to reply, thanks
PCV vent keeps the crankcase from building excessive pressure and then redirects to the intake as does EGR with the hope of burning off the oily excess.
Verify your by pass at idle around the throttle plate with your idle control circuit, look closely at the valve for carbon. Check the throttle plate for carbon build up and pull at least 1 plug and see what colour it is, a #3 or 4 since it is mid block.
3 -5 liters or quarts within an interval of change at about 5000 miles is about a quart per 1000 miles. A too high consumption with theses engines. It may do you well to do a leak down test then a compression test just to see if valves and rings are wearing. An engine will still run with low compression and blow by but you exhaust parts especially the cat will take its toll. Converters do not wear out, they are killed and a loss of 3-5 quarts is quite a lot for a converter to digest.
If your still sure there are no leaks, you can put a filter cloth in or wrap around the final exhaust port in the tail end where the pipe is not too hot, a cloth filter should withstand 452F and the tail pipe at the very end is not that hot. An experiment with a oily filter would show you if you are running that much oil through the engine.
I know that I run no appreciable amount of oil loss and my tail pipe has a black appearance and my throttle plate and intake need 2x a year cleaning, with 3-5 quarts consumed are you guys getting a very dirty throttle and /or dirty intake? Maybe you would like to reply, thanks
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metalfabsteve
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Re: Burning Oil
Well my cats were definately fried probally 90% just replaced 2 so it could pass emissions test. I cleaned the intake recently it could use it again
Re: Burning Oil
--------------------------metalfabsteve wrote:Well my cats were definately fried probally 90% just replaced 2 so it could pass emissions test. I cleaned the intake recently it could use it again
If the cats were dumped and nothing else they will be killed again, a very pricy temporary fix.
If your PCV valve is sucking out too much HC this chemical reaction of hydrogen and carbons will quickly remove the catalytic properties.
Test your PCV and follow the line to the intake manifold and examine for an oil substance. Also your EGR needs a real close look at. Also your intake at the throttle, within the case and test your vacuum with a gauge and see how high it is.
A leakdown and a compression test are in order.
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Towncivilian
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Re: Burning Oil
The PCV valve is in a pretty horrible position on the VQ35DE Pathfinders. It's on the rear side of the engine up against the firewall, and I believe the 2001's PCV valve isn't threaded (2002-2004 are). I don't know if it's necessary to remove the lower intake manifold collector to replace the PCV valve.