The owner of the VAZ 2106, summing up the results of the 50, 000th run, barely restrained his emotions: almost from the first trip, the engine "eats up" the oil. The candle of the first cylinder had to be changed so often that it became a habit. I contacted the service - they changed the caps, "helped" in the first half hour … Then everything repeated. My guys also started with the usual measures, first of all, again replacing the suspicious caps. But a day later, the client returned: he is junking again! It turned out that we were faced not with the trivial wear of any part, but with something new. Indeed, a defect was found … but not at all what they were looking for. For 40 years of repair practice, I saw this for the first time. In photo 1 - the intake valve stem, the cap of which is especially "critical" when it comes to suctioning oil into the cylinder. Where does this deep (almost half a millimeter) furrow come from? Changing the cap for the first time, they did not notice it, and who would look for it? After all, everyone is accustomed to consider the valve a part of the first class of accuracy, and at the same time of high surface purity. But in our age, these ideas seem to be outdated.
Below the main scratch we found a brood of others, smaller ones. Looks like the cap was unsweetened … Now we acted without errors. With a new bushing, valve and cap, the motor worked flawlessly.
Having heard blows under the hood while driving, the owner of VAZ 2111 wisely delivered the car “on a tie”. They removed the head cover - and the owner already whistled: where is the valve? The sleeve hole gapes … The valve fell into the cylinder, at the top there was a pusher with springs and their plate. Here they were even more surprised: both crackers sit tightly in the hole of the plate! What a miracle … But when they looked closely, they did not find scallops inside crackers - they were worn out. After examining the other plates (the head was dismantled), we found that on all the valves there are no gaps between the crackers, which means that their internal diameters are overestimated: such valves are not clamped (photo 2). It turns out that the broken valve just turned out to be the first at the finish, the scallops of other crackers also worn out a lot. Whom to thank, the thing is dark: about three months ago the engine was serviced in a major service - you never know what they could do! It is possible that the crackers are "left".
Of course, we went over the block head. Replaced a broken piston with a suspicious connecting rod, etc. In general, “science” was expensive!
