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.
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.