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I recently removed the head off a Bukh DV20 due to a suspected pin hole leak in the gasket; it was getting progressively harder to start and was down on power.
After removing I dropped the pistons down 50mm and filled with oil as it was going to take a couple of weeks to overhaul and refit. After 1 week the oil level has dropped considerably in one cylinder, the level in the other has also dropped but not as much. I was surprised by this as a recent compression test showed no issues and I expected the oil to hold for an extended period.
How long would you expect a barrel to hold oil if the cylinder and rings were in good condition?
 

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Temp and weight of oil are factors but that doesn't sound unreasonable at all. The oil has to sneak past the butt ends of each ring so any carbonizing or manufactured difference in rings would make an ignorable difference. This butt gap would vary if the pistons were in cylinders of sightly different dia (a bit more honing on one of them) Rings are actually pushed out against the cylinder by gas pressure behind them so not noticeable in a compression test .Just my opinions Experts may yet join in. other factors include tired injectors, valves for starters.
 

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TY. Verry interesting. I would have expected the oil to stay for years. Perhaps the rings or the cilinder or both have worn enough to increase end gap. perhaps, perhaps, perhaps,
I don't know. We need another diesel mechanic to chime in on this. Verry Interesting.
 

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I am a diesel god.
the cylinders that are full most likely have more carbon build up on the rings.
A perfect engine would lose all the oil in a matter of hours. The ring ends gaps are large, at least if you are oil. If they are going to be off a long time coat them with oil and put sticky plastic, AKA self sealing, on the top where the head gasket went. This will keep crud out, and humid air too.
 
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