My 2002 Altima with a 2.5 engine had been increasingly using oil over the past few months. In the past week or two the rate seemed to increase to about a quart every 25 miles if that’s possible. When the engine is cold there is a lot of smoke - more whitish then blue. When warm no smoke. Basically engine is now running pretty rough and stalling once in a while.
I began to search these symptoms on the web and much to my surprise found that this a fairly common problem for the 2002 and also a pretty heated topic as well. The story goes that there is some defect with a few of these engines which Nissan has more or less acknowledged. Not quite really clear on the cause. Some posts claim a faulty cat converter damaged the engines. I’ve noticed a least one post on this forum as well.
In any case it is also clear from reading various postings that the official fix as prescribed by Nissan shops all across the country is to replace the engine. No matter what the exact symptoms might be. I called my local nissan dealer and got the same advice without even bringing the car in. One or two forums even mention a class action suit in the works. This sounds great however it does nothing for my car in the meantime.
At this point I would really appreciate any advice on how to proceed on getting my car back to a reasonable state. Is the recommended engine replacement the only solution.
What are the best steps for diagnosing the cause of this excessive oil consumption.
Thanks in advance for any help.
Well, the best course of action is to replace the engine.
Oh, and don’t forget to replace the cat convertor when you replace the engine, otherwise your new engine will get the combustion chamber sand blasted by the material being loosened from the convertor.
The theory is that the cat convertor that is built into the exhaust manifold, over time, degrades, and material starts breaking free. During the period of valve overlap, that loosened material is being sucked into the combustion chamber, and is causing damage to the cylinder walls, which causes an increase in the piston ring and oil ring gaps, and that causes the increase in oil consumption.
So you have two choices:
Get a rebuilt engine from a Nissan source, or get a used (preferably low mileage) engine from a salvage yard.
Rebuilding your engine isn’t really a cost effective possibility, as most shops are not going to tie up a spot in their garage to take the amount of time it takes to tear down and rebuild a motor.
The easiest way to tell if your oil loss is from increased cylinder wall clearance is via a compression and leakdown tests.
BC.
Yep, Consumer Reports has ‘much worse than average’ for ‘engine major’ for the 2002 2.5l engine. Have you asked in Altima forums about any help from Nissan?
In my experience with a 2002 altima this was due to the computer being soaked by water from the ac condensor. The dealer 5 years ago gave me a replacement that took two weeks to arrive but it was free. The replace the engine may be BS. The action suit mostly involves the issue that the computer was put on the floor hump under the dash just below the joint under the ac coil pan where if the drain hole gets plugged the ac water drips on computer. Now your milage may vary. You could have a bad engine mine only had 55k on it in 2004. The water problem killing the computer probably will live until they move the computer. The oil issue has nothing to do with any engine problem unless you were a bad owner. (1)You have a system leak not involving the engine. A quart every 25 miles and no smoke equals a leak not in the cylinders.
(2)Check the comp first, mine had several times where it dried out and was ok until it finally went in to crap mode.
(3)To help you I would need to know how many miles are on the engine? did you do regular oil changes? Did you pimp this engine and fry it? Has this car overheated?
If you had burned as much oil as you state the smoke would always be blue. The whitish smoke is either fuel or water. Period. The fuel comp is dumping fuel or you have a coolant leak(which you also did not mention). For this problem more detail is required.
During the period of valve overlap, that loosened material is
being sucked into the combustion chamber
I’m trying to envision when this scenario could occur.
When the engine is running, valve overlap is used to take advantage of the momentum the outgoing exhaust gases have (this helps to create a “pull” for the intake mixture). In all my studies of this, I never saw any mention of negative pressure during the overlap period. For all the reasons valve overlap exists, it doesn’t make sense that a negative pressure (which would pull exhaust gas in) would exist.
Thinking about it more, I can see this happening while the engine is starting. If there was no combustion in the cylinder and a piston is beginning it’s intake stroke with some valve overlap, I can see a small window for suction from the combustion chamber.
Do any others have thoughts on how the valve overlap could cause suction from the combustion chamber into the cylinder?
The forums I found mostly had postings from very angry and frustated people. They were all pretty much told by Nissan the only fix was to replace the engine. I really would like to hear from someone besides Nissan.
Thanks for the reply!
It just seems that replacing the engine is pretty extreme considering the car does run. I was wondering if an option is to remove the cylinder head and have a competent mechanic take a look. I know this is a big job but maybe not as big (and costly) as replacing the entire engine
Thanks for the reply!!
I’ve been carefully checking for leaks but havn’t found any. I guess it could be leaking when the engine is running and the oil is just evaporating off the hot engine.
Thats interesing about the smoke because it is going through coolant as well but not nearly extreme as the oil.
The mileage is 110,000. I think for the most part I was pretty regular about oil changes although I can’t say I was replacing the oil every 3000 miles
Here is the way I envision how exhaust gases could be pulled back into the cylinder. During high speed coast down, the intake manifold vacuum is very high. In addition, the fuel injectors are cut off so there is no combustion heat to expand the compressed charge. On the intake stroke the intake valve(s) close (ABDC) on vacuum. Through the compression and expansion stroke no additional air and minimal heat is added to the charge. When the exhaust valve(s) open, there will remain a vacuum in the cylinder. Exhaust gas will be pulled back in and then expelled during the completion of the exhaust stroke. Then during valve overlap more exhaust gases will be drawn into the cylinder and into the intake through the partially open valves.
This problem with the Altima engine is interesting.