I am having an unusual problem with my Yanmar 3YM30 Diesel
developed an unusual roughness on a cold start.
It was time for service
, so I changed both the primary (Raycor) and secondary fuel
filters, and the engine
air filter. This helped, but did not fully eliminate the problem.
Currently, when I cold start the engine it initially starts up smoothly, but within 15 seconds it begins to shudder, as if missing in one cylinder; 15 seconds later the shudder settles down to alternating between smoothness and roughness once per second.
The belts are new, and properly tensioned. The impeller was changed based on time, not wear. The oil
and filter was recently changed. The coolant
is correct. There was no water
in the fuel
. I have allowed the engine to idle for some time, with no change. I have slowly brought the engine up to full speed while in neutral, with no change.
The engine tach reads 850 rpm