Knocking Sound from 03 QX4

[coledog188]

I guess my QX4 burns oil, I didn't realize it and it ran a bit low. The oil light never came on which was weird, but after adding 4 quarts of oil it finally registered full on the dipstick.

In any case, now I have a knocking noise going on at idle especially. It also has a bit of a rattle when giving it a little gas.
My mechanic friend said it sounds like a rod is about to go...

My questions are:
Is it most likely a rod?
What's my best course of action without dropping too much money just in diagnosing it?
Should I get a new used engine off ebay with a 90 day warranty and have that dropped in? (there are quite a few with around 100k miles for $900-1000.)
What else could it be?
Fixable?

It's an 03 as I said, 4th digit on the VIN is a D. Has 169k miles, gotten make the car last another 3 years!

Lay it on me...


EDIT:
Sounds a bit like this video, just not as bad: http://www.youtube.com/watch?v=BfIOfozFpVc

[Towncivilian]

Four quarts low is a significant amount. How long ago did you change the oil?

There is a potential issue where no threadlocker was applied to the power valve screws during assembly. The lack of threadlocker allows the possibility of the very small screws to back out of their screw holes due to vibration, and get eventually sucked in by the engine when the power valves are actuated, potentially causing significant engine damage. It is not known which specific VINs or years are affected.

Check your power valve screws by following this guide: threadlocker-on-power-valve-screws-pics-t304263.html

If any are missing, you are most likely on borrowed time with that engine, given your knocking noise. If all are present, apply red threadlocker to all 12 screws and button things back up.

Are you the original owner of this vehicle? Have you changed your engine oil and filter at the correct interval (3,750 miles for severe service)?

[coledog188]

It's been about 4000 miles since I last changed my oil.

I haven't checked the valve screws, I'll print off the guide and take it to my garage.

No, not the original owner, I bought it at 96k miles two years ago.

[Towncivilian]

Consuming about a quart of oil every 1000 miles? That is generally deemed excessive. Are there no oil leaks? Did the previous owner supply any service records to get a glimpse of an idea of how often the engine oil was changed?

[coledog188]

It was owned by an Infiniti dealer employee. Every last service item was take care of by the time I bought it based off the records he gave me. Oil had been done on a regular 3-4k schedule.

I can't see any oil leaks, we have snow on the ground up here and it's clean under the car.

[Towncivilian]

Well, that just points more towards something like a power valve screw and not lubrication-related damage or failure, in my opinion. If the previous owner had the oil changes done at a dealer, no doubt they have service records. If it turns out to be a power valve screw working itself loose, I would suggest calling 1-800-NISSAN1 and trying to see if you can get any compensation. Nissan may require logs of your oil changes too, so I hope you kept logs or receipts.

If all the power valve screws are ok, the oil consumption may be caused by a bad PCV valve or worn out/stuck piston rings. You can replace the PCV valve while you're checking the power valve screws, but you need to remove the lower intake manifold as well. When I did my power valve screws, I just removed the upper IM and applied threadlocker - the power valves need a rather large amount of force to actuate, so I didn't have much worry of dropping a screw into the intake. If you choose to replace the PCV valve, definitely apply threadlocker when the UIM is off the vehicle. You can read my PCV valve replacement story if you want to get an idea of what not to do.

Worn out piston rings is a larger challenge to fix and would require a significant amount of work to replace.

As for the knocking noise, I'm not too sure. Did it go away once you added oil to the full mark, or is it still present?

[coledog188]

The noise is still present, after filling it up a couple days ago.

I'm going to check the levels again tomorrow morning after warming it up add more if it needs it.

I've been running full synthetic in it, oil changes every 3500-7500 miles since I've owned it. Since I started noticing the oil light coming on (about 6 months ago) I've been more diligent about changing the oil and checking my levels since it's been consuming the oil. I had heard a little tick before when it got low on oil, but nothing this bad...Also when I would fill it up the noises would go away and the purring would be normal.

[coledog188]

Here is a video during acceleration, if you turn it up you can hear the knock especially during the shift.

http://www.youtube.com/watch?v=rE7XfPFNPWE

[CanuckQx4]

That motor sounds like its about to lock up. Dont drive it like that

[coledog188]

Well...It's officially done for.
I'm looking for a cheap engine at this point...Something sounds horrible in it and there's no power.

Recommendations for used engines? I found a few with 90 day warranties on Ebay for about $900-1000 and about 100k-130k miles on them.

I really don't want to put a lot of money into the engine when I only plan on keeping the car another 3 years...Suggestions please!

(Also, if anyone has a wrecked QX4 and wishes to sell the engine...I'd be interested!)

[Towncivilian]

Sorry to hear that. I don't know of any sources for used engines.

If you end up swapping the engine at some point, could you take the upper intake manifold off the "dead" engine to check the power valve screws regardless? I'm curious to see whether it was indeed one of the screws falling out.

[coledog188]

Will do!

And I plan on swapping engines...I have a loaner car from my brother but I crave my QX4 badly after only a few days.

[yeldogt]

I am a bit confused? You say no oil light and then you mention that the light has been coming on for 6 months?


The oil light is the oil pressure light - it was telling you the pressure was low ... maybe the pump was going or the miles on the engine reduced the pressure --- the lack of pressure will quickly starve parts of the engine of lubrication and cause problems.


As with any old car like this you need to get different estimates and weigh the cost vs replacing the car.

[Towncivilian]

The oil pressure light is triggered when the oil pressure is too low to maintain idle speed. It's just a dummy light that goes on below some specified value (4 PSI or something); it's not variable at all. It might go out once you start hitting the gas since pressure would rise assuming there was any oil left in the crankcase.

I missed the part where you say you've been seeing the oil pressure light come on rather frequently for the past 6 months... how low was the oil level when the light would trigger usually? I suppose it doesn't matter anymore since the engine is shot now, but still...