My old sad and forlorn M25 has been languishing in my plant since the summer.
An acquaintance took the engine to a retired diesel tinkerer a couple of weeks ago
Much to my utter surprise he had the old lump running on modified stand and water supply.
I wish I had found this fellow earlier.
It was running like new.
Diagnoses:it was indeed missing on 3rd cylinder but not due to bent rod, it was improper valve clearance
One valve was completely closed under load and temperature. That explains why it ran ok until load and temp increased
I have no idea why the original mechanic nor the marina mechanic checked this.
Andrew : That will do it every time!!!
Sounds to me like it was hanging open not staying shut after it gets hot. How would a valve stay shut after reaching operating temp? That engine does not have hydraulic lifters does it? It can't that's why there are valve clearance settings? (just trying to learn...)
I am only going by what my new friend Joe told me.
There was only 1 thou clearance on one valve ..so if to stayed open or closed up, I don't know.
BTW he bought the engine to add to his collection. says he will use it to run a generator.