I had a bad gas of muck growing in the
fuel system of my
Yanmar 3ym30. I cleaned the tank, the lines, replaced the filters and sent the injection
pump for servicing. Replaced the injectors.
Re-installed the injection
pump and injectors. Checked the timing (16 +- 1 deg BTDC), bled the filters.
Got the
engine started after a few attempts. Ran well from 2,000
RPM to 4,000
RPM, but idelled badly and then would cut out.
Found air at the bleed screw. Bled, same again.
Eliminated everything on the suction side until I had clean
fuel from a jerry can feeding directly to the
lift pump. Same again.
Checked the
oil and found a very high level. 1.5 times full! Not milky. Dropped a drip of
oil fluid on paper. A ring appeared, indicating
diesel in the oil.
Suspected the
lift pump of introducing air and pumping
diesel into the oil. Took it off, inspected the
diaphragm, maybe fine cracks but no visible oil.
Ordered a replacement lift pump. While waiting for it drained the oil through the dip stick and also via the banjo bolt that hold the dip stick tube to the bottom of the
engine.
Installed new lift pump. Re-installed banjo fitting bolt at bottom of engine. Changed
oil filter.
Poured one liter of new oil into filler on top of valve cover.
Then went to turn over the engine using a wrench and the crankshaft pulley bolt so as to help distribute the oil. The engine should take 2.8 liters.
Oil level is below dipstick.
Cannot shift the engine clockwise. Anticlockwise unscrews the bolt.
Checked that engine is not in
gear.
Maybe the lift pump cam was locking the camshaft in the injection pump.
Removed the new lift pump. Still seized.
Suspected
water in cylinders. Maybe syphon via
water pump">raw water pump but Seacock was shut after I last ran the engine. Checked
muffler anyway. Found drain screw. Opened, very little water trickled out.
Muffler was not heavy so discounted that thought.
Took out injectors to ensure that I was not trying to compress fluid, water, diesel, oil, whatever. Still cannot turn crankshaft. Nothing coming out of injector
ports.
Suspected injection pump. Maybe the seal went which could account for the diesel in oil, and then maybe the injection pump seized.
Removed the injection pump
gear. Crankshaft Still seized.
Considered a stuck starter
motor. But that would not seize the engine.
Alternator and fresh
water pump and
raw water pump are belt driven. Eliminated them.
I am left with seized pistons, valve problems or ??
My latest theory is that the engine was running at high revs with unknown to me, oil diluted with diesel. While waiting for the replacement lift pump, the piston rings seized.
My next step is to run freeing oil into the cylinders via the injector
ports and let soak for a few days.
Maybe also remove the valve cover and look for bent valve stems.
Please any serious suggestions? I am running out of ideas here.