Originally Posted by nes
had very specific directions against running at low load (less than 30%).
The reason given for the load restriction was lower cylinder pressure at low load. The piston rings are designed to operate at rated load combustion pressures, this ensures normal lube oil consumption
rates. Light and no load operation promotes “souping”, which is excessive oil
escaping past piston rings into combustion chamber. Souping causes smoking exhaust
and potential exhaust
Yes, forgot about that. I know it as 'slobbering' and it can make a mess out of your exhaust system. It can also cause buildup in the combustion chamber as it just runs too cold. Also, according to what I have read (no first hand experience thank God), this condition can become permanent if the engine
runs under those conditions too long. I gather that both the rings and cylinder liner get damaged over the long term.
I have not heard mention of exhaust fires but can see that happening if the engine
is run on idle for a long time.
I should clarify one thing - in my opinion (and no, I can't back it up), running at just above idle 'should' be ok if the engine is heavily loaded. Having said that, I tend to run around 2000 rpm
to cover my butt.