Originally Posted By: bmwtechguy
The problem with these engines is mainly the rear bank oil drainback holes in the cylinder head getting plugged shut. The holes are not large enough. As sludge starts to build up from infrequent oil changes or lots of short trip driving, the oil begins to collect in the top of the cylinder head instead of draining down, and eventually the 3 drainback holes can plug completely, causing the white smoke that you are seeing. I worked on a 2001 Avalon, same engine, and at every cold start he had 5 minutes of steady, white billowing smoke and all the other symptoms you mention. We went the ARX route, but had to keep adding Auto-Rx to the oil as we added oil to keep a therapeutic dose of the stuff in the crankcase. We were able to get the oil light to stay off, but never got rid of the smoke or excessive consumption, which actually got up to 1 qt every 2-300 miles. We cleaned and then rinsed for quite some time/mileage, and if anything, the smoke and consumption actually increased some as the gravity drainback holes became completely plugged shut.
While I like Auto-rx and have used and still use it with very good success, there are limits to what it can do. It must have flow to do any good, and when the gravity flow STOPS on these drainback holes, Auto-Rx cannot clean them out. Then you have engine oil pooled and sitting there on your valve stems, getting sucked down by manifold vacuum, or draining down the valve guides into the combustion chambers while the engine is off, making a mess of your plugs, catalytic converter, etc. Eventually you will notice the tendency to have preignition from all the oil and combustion chamber deposits forming. This can be lessened by going to a higher octane fuel or adding some type of water vapor induction like we did.
Eventually we went in there and cleaned it all up, which was quite a job. That is when we observed all of the above. When the job was done, then consumption went back to a much lower, normal level, with zero smoke at any time. Unfortunately, the car was totaled 2 weeks afterwards, so we never got to see the long-term results.
My advice to anyone with this engine is to be careful about doing too much cleaning all at once, since it seems very easy to plug up those rear drain holes completely if the process has started already. The only way to reverse that situation once it happens is to clean them out manually, which means going into the top of the engine and probably the bottom as well.
So should I try Seafoam after ARX? And does those engines have gasket under valve cover? All u said about back drainage makes sense. I seen some oil there when changed plugs. Some smoke comes out just right at start up, and stops right away, just a puff.
Otherwise after driving another 50 miles yesterday I noticed that engine became little less noisy at cold start ups. I mean it is very quiet from the day I got it, comparing to Altima with 3.5 and chain with messy tentioners.
