Help me diagnose engine issue please.

drcoastline · 01-07-2019, 06:25 AM

Vehicle is a 2007 Nissan Xterra 4.0 V6.

Short history. 238,000 miles nary an issue in ten years. Until this year simple routine maintenance. The fuel temperature sender went bad which caused the check engine light to go on so I could not get the vehicle inspected. As I was waiting for the sender unit to arrive a multi cylinder miss fire in bank one developed. I assumed one of the Cats went bad so I replaced all four and all four O2 sensors. I also replaced the fuel pump/ sender unit.

Recently the Xterra started consuming oil, which it never did. Excessively consuming oil. like four quarts in one month or less than a few hundred miles. It also began billowing white smoke at start up. I did an oil change including filter and replaced the PCV valve. Air filter is clean. For a few days it seemed the problem was fixed. This morning I started the vehicle and again it is billowing white smoke. Checked dip stick, no oil. Temp outside is about 30 degrees. After about five minutes the smoke has mostly cleared. However, there is a wet spot on the pavement under the tail pipe. Smoke smells like petroleum not antifreeze. Also no drop in antifreeze level.

No oil stains on my driveway and engine block is dry except for where I spilled the oil trying to refill the crank case. so not a leak and running out.

flatbutt · 01-07-2019, 06:29 AM

Just a WAG but have you checked the coolant?

VincentVega · 01-07-2019, 06:31 AM

Nissan v6s are known to use oil. Check out the oil baffle in right valve cover. Compression test would help but cover is quicker, IIRC.'

good luck

fastfredracing · 01-07-2019, 06:42 AM

Missfires , coupled with loss of oil, and 240k sounds like you are going in.
Your next logical step is a compression/leakdown check .
I am not familiar with any known engine problems with that model.

onewhippedpuppy · 01-07-2019, 06:55 AM

Agree on the compression/leakdown test, that would eliminate an internal engine issue. Normally oil consumption starts gradually, so that's a little odd.

legion · 01-07-2019, 07:04 AM

It's almost certainly a worn part that seals better once warmed up. Piston rings, etc. Worst case, it could be a crack in a cylinder wall.

My guess is that it won't be cured without taking apart the engine. If you want to keep the vehicle, it might save you time/money to find a replacement engine rather than try to diagnose/fix what is already there.

wdfifteen · wdfifteen's Garage

Leak down test. Listen at the radiator cap as well as the tailpipe and intake.

ckelly78z · 01-07-2019, 07:51 AM

Somehow, your oil is most likel;y mixing with your engine coolant. Coolant in the combustion chamber will produce the white smoke, and i would venture a guess that the missing oil is in your radiator.....blown head gasket ?

T77911S · 01-07-2019, 08:01 AM

you have blown a head gasket.
does not need to over heat to do it. 240k miles, could be time for it to go.

pull the plugs and take a look at them, probably have one that is wet and oily.

flatbutt · 01-07-2019, 08:36 AM

Flatty guessed correctly?

Arizona_928 · 01-07-2019, 09:27 AM

Quote:

Originally Posted by legion

It's almost certainly a worn part that seals better once warmed up. Piston rings, etc. Worst case, it could be a crack in a cylinder wall.

My guess is that it won't be cured without taking apart the engine. If you want to keep the vehicle, it might save you time/money to find a replacement engine rather than try to diagnose/fix what is already there.

I'm going to guess valve stem seals/guides.

john70t · 09:57 AM

Quote:

Originally Posted by T77911S

you have blown a head gasket.
does not need to over heat to do it. 240k miles, could be time for it to go.

pull the plugs and take a look at them, probably have one that is wet and oily.

What he said.

I was going to say use a bunch of Marvelous Mystery Oil with an Eye-Talian Tuneup to see if it is a sticking oil scraper ring or leaking valve stem from carbon buildup.
Then Sea Foam at idle and an oil change or two.

The white is probably water/coolant. test with a piece of paper.
A pressure test on the cooling system can be done as well.

ckelly78z · 01-07-2019, 09:55 AM

Quote:

Originally Posted by AZ_porschekid

I'm going to guess valve stem seals/guides.

That would give him a blueish oil smelling smoke, not white, That is the sealing between the head, and the combustion chamber which would allow oil to pass through if the rings were also bad. Coolant is in the passages around the combustion chamber, but should not ever be present IN the CB.

fastfredracing · 01-07-2019, 10:08 AM

I do agree with you guys who say that looks like coolant/'steam instead of oil , but he says he has not lost any coolant, and is guzzling oil .
Mark the overflow bottle with a sharpie, and see if you are indeed loosing any . Check it cold every morning for a week or so. If its steaming coolant, you are loosing coolant

RKDinOKC · RKDinOKC's Garage

Need replaced from the tires up.

T77911S · 10:23 AM

my neighbor had and xterra. she had some kind of oil problem that made her sell it but I don't think it was coming out the exhaust. you know how it is trying to get auto info from a female.

blown HG's don't always loose coolant. they don't always effect the oil.
you could check coolant pressure. there is also a HG tester you can buy that samples the coolant for exhaust.

you also don't have to over heat it to blow it

first thing I would check plugs!!

Ayles · 01-07-2019, 10:21 AM

have you done any research on thenewx.org?

there might be some good resources there.

And as an Xterra owner sorry to see you are starting to have some issues.

onewhippedpuppy · 01-07-2019, 12:31 PM

240k, she had a good run.

If you DIY, doing a compression or leakdown test as well as a cooling system pressure test is pretty easy and cheap. Most auto parts stores rent/loan the tools to complete any of the three, and they are pretty non-invasive. I'd definitely do that before throwing more parts at it.

drcoastline · 01-07-2019, 02:36 PM

Thank you all for your input. Tomorrow I will run some of the test you all recommend. Check the plugs, pressure test the coolant system, I'll mark the over flow bottle etc.. Assuming it is not to cold.

Update

Following my post this morning, I topped off the oil, about 2.5 quarters to get it in range. I drove it about 150 miles. I got back a short time ago. Let the car cool off before checking levels. Coolant was a bit low. It took about thirty ounces of coolant. Checked oil and still acceptable.

T77911S · 01-08-2019, 04:38 AM

was it still smoking?

pull the plugs.

one thing you have to look out for is hydro lock.
I had a Volvo that the wife over heated and blew the HG. (drove it for a about 2yrs, maybe more like that). every now and then she would complain it would not turn over, then a little while later it would.
it would hydro lock but then it would "relieve" itself and start.

here is the REAL pisser about that whole deal.
I got my moms Volvo after she wrecked it.
did a motor swap, lots of work to "upgrade" her engine to my newer one.
I was running it for the first time. it ran for 30-45 minutes just fine.
when out to my truck to get gauges to check the AC and it over heated and blew the HG..again.
so I pulled the head and broke 2 head studs off in the block.

I literally pushed it out in the yard and put several rounds into it. I was done.....