# Oil consumption issue??



## blocksbikes (Mar 2, 2012)

Got a 2002 Altima with a 2.5L that has 200,000km and it started loosing power. Found that the catalytic converter was getting plugged and had it changed out. Car has all of its power back but now its using a litre of oil every couple weeks?? Never used oil before and always had oil changes done every 3000km's. Can someone tell me why this is?? The car has no leaks and does not smoke on start up nor does it smoke while driving. Also checked the tail pipe and no signs of black moisture there either.

Anybody got any ideas or have the same problem?? :wtf: 


Thanks


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## rogoman (Dec 16, 2004)

If your car uses a 4-cylinder QR25DE engine, then the following can occur:
- Vehicles with the QR25DE may ingest material from a damaged pre-catalyst resulting in increased oil consumption.
- Power valve screws in the intake manifold may become loose and result in unstable idling or power loss.

This was a problem with some of the early models from 2002 to, I think, 2006.


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## blocksbikes (Mar 2, 2012)

So if there was a problem with the old cat that was swapped out, would I have not been having oil consumption issues then? There is no loss of power or idle issues... the car runs great. 
Any other ideas??

Thanks


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## smj999smj (Jan 1, 2006)

The oil was likely what caused the catalytic converter to fail. It's a common problem. As mentioned, the catalyst media in the exhaust manifold/precat assy. breaks down. The QR25DE uses valve timing for exhaust gas recirculation rather than a conventional EGR valve setup, so the exhaust valve partially opens on the intake stroke to suck the exhaust gas back through the valve and into the combustion chamber. With the catalyst media being sucked into the combustion chamber along with the exhaust gas, the cylinder walls begin to get scratched and eventually start burning oil. There was a recall issued for this concern; you may want to see if it's still "open" for your vehicle. The recall covered a number of checks and upgrades, including reprogramming the ECM with an updated program, replacing the catalytic converter heat shields with redesigned shields, in some cases replace the catalytic converter and engine short block.


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## blocksbikes (Mar 2, 2012)

Thanks for the info smj  I get all what your saying but still do not know why if the cat media was breaking down before why was the car not using oil then? Its only after we changed out the old cat for a new one that it started using?

Thanks


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## rogoman (Dec 16, 2004)

At this point to further diagnose your oil burning problem, carefully examine all the sealing points around the valve cover gasket; you may have a leak there without realizing it. Also remove all the spark plugs and examine them for oil fouling. While the plugs are out, do a compression test on all cylinders. Let us know what you find.


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## blocksbikes (Mar 2, 2012)

So I did check for any and all leaks again and nothing.....but when i went to remove the spark plugs I found in a couple guides that lead down to the plugs there was a couple cc's of oil sitting down in the hole. I did not remove the plugs to do the compression test because i did not want the oil to drain down into the cylinder. Does anybody know where this oil came from??

Thanks, D


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## smj999smj (Jan 1, 2006)

Spark plug tube seals in the valve cover are leaking. This will not cause a heavy oil consumption issue, though. Oil going into the cylinder won't hurt anything; you can always turn the engine over with the plugs removed to blow the cylinders clear. Proceed with the compression test, and if you have the equipment, a cylinder leakdown test.


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