I am posting this in case others come across similar issues as I am sure it doesn't matter the make or model - a diesel is a diesel! Mine happens to be a 1978 Ford 1600 2 cylinder diesel.
Symptoms - tractor would not start one day even with the help of gas or ether. When it was running it would occasionally throw coolant out the radiator overflow tube. Coolant was black in color.
Attempted fixes (not in order) - bled fuel lines, removed and cleaned brushes on starter, checked glow plugs, removed and cleaned injectors, checked battery for proper amperage, checked to make sure no load was on the engine (hydraulics, etc). Checked oil level - engine was not making oil and was the proper color. Since everything else checked out a lack of compression was suspected.
Successful diagnosis - tore the engine down and found the head gasket was partially corroded which caused a loss of compression (hence no start) and when it was running would allow exhaust gasses to mix with the coolant and create pressure that would throw it out the overflow. I also had the head machined and checked for cracks while I had it off. Replaced head gasket and tractor fired right up. Flushed coolant system many times to remove exhaust sludge.
Lesson learned - OEM head gasket was $130 - very expensive tractor!!
Question - previous owner had replaced head and head gasket only 6 months ago (aftermarket). I don't know if he had the head machined.
What would cause the gasket to corrode? Diesel fuel and coolant are not corrosive are they? Anything I should do to avoid a repeat? Thanks.