In Reply to: Re: Well it's begun posted by Jerry on August 04, 2018 at 18:34:14:
Residue from the additive package the oil companies use to help control the amount of exhaust emissions in the fuel they produce. May have been running a little hot and lean also. You will find the residue is HARD.
If the engine ran well, reasonable oil consumption and pressure, has good compression ran, in normal heat range prior to the oil pump failure a set of bearings, rings and valve grind would probably do the job.
Obviously you will have to gauge all the wear surfaces, liners, barrels, pistons, piston pins, etc. If there is no ring ridge and the taper is in the mid range of the wear limits, I'd leave them alone. Replace the valve springs, they are cheap. Unless you have access to a New Way QikKut cutter or grinder you may have to send out the block to a machine shop. No need to to remove the crank.at least for the shop here.
However if the valves look good, no pitting, not burned or wqarped, nice even shiny sealing surface slightly away from the margins and the seats look the equally good, a clean up and lapping should do the job.
Eyeball the intake ports for heavy oily residue. Its presence indicates worn intake valve guides. It's not as prevalent in the flatheads as in the OHVs though. Easy to replace. Or..... go old, old school and knurl the guides. (OMG!!!, did he just post that? and in 2018 no less? Head slap,X2.). I know, I know if they are cast no point in even trying. I didn't replace mine. I'll have to keep the Rs down along the back straight at MIS I guess.
FInally depending on how badly the oil pump was trashed, spend a lot of time and use a lot of solvent cleaning the rifling and oil galleries in the block, especially the crank. (I don't remember if the plugs for the rifling in the crank are accessible with the crank installed. If so try to remove them and flush the crank with solvent. Time spent here is time well spent. Minimal investment. When you get it reassembled and started I would run it for a few minutes just enough to get the oil circulated. Drop the oil and filter and replace. May not be necessary but it's something I would definitely do.
It sounds like you have had your fingers in the guts of an engine so a time or two so some or all of this may be redundant.
ANd finally............ If it were a Lycoming 0360 C1, (one variant is Marvel Schebler carbureted BTW) it would come out, get completely disassembled, inspected, boiled out, then reassembled with any out of spec parts regardless of TBO.
Since I don't have a Power Plant certification, I can't get my fingers into these engines.
However if your tractor was limping along and you were "trying to get just one more season out of it before it shells." by all means do an out of frame. ANything less is false economy.