Toyota Engine 1mz-fe

[Lien Kocurek]

Im posting this in hopes it will help someone else. This is my personal vehicle. I've had this vehicle quite a few years, and put a lot of miles on it. When it started to burn oil, it had around 170,000 miles on the odometer. I am the second owner, and I always changed the oil regularly. I did switch from synthetic blend to full synthetic oil. At around 170,000 miles it began to smoke badly on startup, and use quite a bit of oil. I tried changing the PCV valve and using various chemicals to clean the inside of the engine, but nothing helped. I finally decided to tear the engine down and put piston rings in it. There was no ridge on the cylinder walls, and you could still see the crosshatch. The oil rings were badly sludged up in the ring grooves. I replaced the rings and valve seals, and touched up the valves. After putting everything back together, I still had the same problem as before. On some Toyota 3.0 engines, there is a TSB for a redesigned rear valve cover to address an oil consumption concern, but I couldn't find one for my particular vehicle. I decided to look up a new valve cover anyhow, and I found that the part number for my vehicle had been changed to one for an updated valve cover. I ordered the valve cover and installed it on my engine. I immediately went from using probably a quart of oil in 500-700 miles to using no oil at all, and no smoke at startup! I took the old valve cover apart and I could see nothing wrong with it. I was expecting it to be sludged up inside, but it was pretty clean. I'm just trying to figure what happened to my old valve cover that made the engine suddenly start to use oil after all the miles it had on it. I also wonder what Toyota changed in the design in the new one. Apparently Toyota neglected to apply the TSB to my particular vehicle, but it did apply. Hopefully my headaches will help someone in the same situation.

Holy shit I was just about to take apart my 1mz-fe in my Highlander for this problem. Already did PCV and valve stem seals which slowed the consumption down, but still uses quite a bit. So also thought it was time to take it apart and free up the oil rings. I will get a valve cover ordered. Thanks!

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