New valves in slightly-used guides/seats?

[Walt Fricke]

Magnus - like you, I don't think leakdowns damage bearings. If they did, among other things, you'd expect to see a crosswise line on each rod bearing for each leakdown, though maybe not on the mains. These don't appear.

But I understand the puzzlement, as the surface of the bearing is soft so foreign particles can be imbedded and not scratch the crank journals. And the oil wedge separating the crank from the bearings is dynamic, created by the oil pump on a running engine (hence the value of an Accusump to prepressure the oiling system, if you feel the need). All authorities state that starting creates the most (concentrated?) routine wear because the oil pressure hasn't built up.

But I'm not going to loose sleep over it any more than I do about where the missing mass of the universe might be.

[safe]

Originally Posted by Walt Fricke

Magnus - like you, I don't think leakdowns damage bearings. If they did, among other things, you'd expect to see a crosswise line on each rod bearing for each leakdown, though maybe not on the mains. These don't appear.

But I understand the puzzlement, as the surface of the bearing is soft so foreign particles can be imbedded and not scratch the crank journals. And the oil wedge separating the crank from the bearings is dynamic, created by the oil pump on a running engine (hence the value of an Accusump to prepressure the oiling system, if you feel the need). All authorities state that starting creates the most (concentrated?) routine wear because the oil pressure hasn't built up.

But I'm not going to loose sleep over it any more than I do about where the missing mass of the universe might be.

Yes, and I started thinking and got confused too. I remembered that someone told me to not worry about oil pressure the bearing builds its own pressure as log as its feed oil. So I googled...

The old saying that startup and shutdown induces the most wear is true, but not from lack of oil or oil pressure, its from the fact that the crank is not moving or moving to slow to build the required oil film.
There are bearing that are floated on oil pressure but they seam to be a very specialised bearing for large equipment.

https://www.machinerylubrication.com/Read/779/journal-bearing-lubrication

So, I'm still confused but yet again not worried about a leakdown.