Damaged cylinder smoothness of BMW engine – how to fix it?

BMW driver question – details of the damage to the smoothness

In my engine, the bottom of the piston was burned all the way to the ring, and the smoothness has a depression (visible in the photos), probably from the burn and fragments of the piston. The compression pressure on this cylinder was 0, and on the others it was about 16 bar and on one 14.5 bar. Before the incident, it was less than 15 bar on all of them.

I took diameter measurements in two perpendicular directions on the three cylinders and the differences (so-called ovalization) were 0.40 mm, 0.20 mm and 0.20 mm, respectively (measured with a traditional caliper to the nearest 0.05 mm).

The exhaust valves of the damaged cylinder gently “flopped”, as they show leakage after several minutes of soaking from the top with gasoline. The rest of the valves and seats seem to be fine, not letting gasoline through, but we would have to check this carefully. The seats are most likely coated with nicasil. Please advise.

The problem was with BMW 5 E39 with M52B28 engine with single VANOS, but it may happen in other models as well.

Response from BM Cars service – the economics of repairing a damaged honk

From the described damage to the engine, it appears that, unfortunately, the cost of repairing it will exceed the value of a functioning used engine purchased on the secondary market.

In the case of damage to the cylinder head, there is an additional need to replace the engine block, which increases the cost dramatically. Prices of engine parts are also very high and not all of them are attainable as replacements. He suggests looking on the aftermarket for a working engine with a start-up warranty. The cheapest version is a post and gear ratio from your engine.

For an accurate diagnosis, it is necessary to carry out additional checks.

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