2002 Nissan Altima: 2.5L 4-Cyl Automatic Leaking

2002 Nissan Altima: 2.5L 4-cyl Automatic..leaking

Customer Question

I have a 2002 Nissan Altima, 2.5L 4-cyl Automatic. For a while now (~ 1 year), it has been using a lot of oil. It is not leaking it - no puddles ever. It really doesn't smoke either. I've been suspecting the fuel system (see more below). It doesn't take long after an oil change for the oil to start looking black and thinned out like maybe the cylinders are being washed down with too much gas. When I crank the car in the morning it will also clatter some. Additionally, it idles rough. Sometimes, it idles very smooth, but not for long. Sometimes, it may be idling fine and smooth, then the engine RPM suddenly drops 200-300 RPM and pops right back up, but then it idles rough. It's not the A/C kicking in (since the A/C is off) and I don't think it is the alternator kicking in (I've replaced the alternator twice). I've also replaced the engine belt idler pulley. I've also replaced the PCV valve recently. I've also experienced some flooding issues that seem to be common with this year model. It doesn't happen often (couple of times a year after it has sat for a few days without running), but when it does, I cannot get it cranked until I replace the spark plugs. Sorry for such a long description, but I wanted to make sure you knew of the symptoms.

Submitted: 3 years ago.

Category:Nissan

Share this conversation

Expert:Jay replied3 years ago.

Hello and thank you for using JustAnswer.com
I am afraid it sounds like you may have the common symptoms of engine contamination. Let me explain.
On the 2002 and the 2003 2.5 engines the exhaust manifold design with the catt converter had some issues.. Now these issues still carried out through to 2006 models, but the redesign of the exhaust manifold in 2004 lower the rate of this happening. What happens is the catt converter towards the top of the exhaust manifold breaks apart. When this happens, the debris can get sucked into the engine. This happens more so since Nissan eliminated the EGR system. I feel and other techs feel that if Nissan left the EGR system on these engines this wouldn't happen. When the debris gets sucked into the engine it mixes with the oil and becomes like a lapping compound. A lapping compound is what they use to seat valves into the head and grinds away the metal to make a nice even seat. Anyway, when the debris mixes with the oil, this lapping compound is now circulated through out your engine contaminating it. It start by taking out the oil rings, so it causes oil consumption issues. Once this happens, repairing the engine is useless, since it's now contaminated. The next things that can fail is the head gasket and compression, until there is complete engine failure
So most likely this is your problem I am afraid. The only way to correct it would be to replace the engine. Do not rebuild it. I don't recommend getting a used engine either for this same reason. At the same time, a reman engine is not much more money than a used engine. That is what I would recommend. Then if you do decide to replace the engine, remove the exhaust manifold with the Catt Converter and replace it with a Exhaust Header with a rear 02 sensor spacer. If you do that, then this problem will never damage the new engine and will last.
These are not bad engines, it's just the catt converter is the cause of all the engine issues I am afraid.
If you have any more questions on this, please feel free to ask. Thanks Jay!

Ask Your Own Nissan Question