HST limits

[betsy]

I recently got an 80's T1600 2 cylinder diesel lawn tractor, with deck. I am a retired bicycle mechanic and am trying to get up to speed and Diesel engines and hydrostatic transmissions.
The tractor sat in an unheated garage for close to 3 years. When starting it it takes quite some time to get going and puffs a fair bit of black smoke when it does. I consider using sea foam or some other product to clean out fuel system but am hesitant. I have put in 20 litres of diesel.
Second concern is that I use it to haul firewood, gravel and fill and even a Digger (tow hoe) that weigh 2000lbs.
My woods road is fairly smooth but at times reaches close to 30% grade. My trailer uses bicycle wheels with cable disc brakes which I keep engaged when going down hill. The tractor still seems to work at not letting things run down hill. Should I be concerned about burning out the motor, and more importantly the transmission.

 

[GeoHorn]

30-percent grade is a change of 30-feet over 100 ft distance…quite a steep grade. It will be important to avoid roll-over in the side-ways … but, additionally to recognize that travelling uphill can flip the tractor longitudinally if sudden-acceleration -forward should occur. It may be safest to travel Uphill in Reverse.
Keep all loads at lowest-position, to avoid elevated center-of-gravity of the machine/combination.

Using lower gears, a 30% grade will not harm a healthy tractor.

Maintain a ROPS system and Wear your seatbelt at all times on that slope.

SeaFoam and additives are unlikely to repair significant fuel/air ratio problems. Black smoke is indicative of excessively-rich fuel/air ratio. Is the black smoke reduced shortly after the start-up? …. or is it still present even after the engine is thoroughly-warmed up… ?

My opinion is worth what you paid for it.

 

[William1]

Do you... use the glow plugs on start? A puff of smoke during cranking is normal as fuel is injected in as it cranks until it finally fires off. That puff of smoke is usually the first few squirts of fuel sitting in the exhaust before the engine lights off.
Do be VERY careful for your safety on step hills. Well ground can be very slippery and once traction is broken, it could be a wild ride. When I tractor, traction and angles are the foremost concern in my mind. Not worth having a machine doing the heavy work if it kills me.
HST's are terrific, the maintain speed (power or braking) using fluid (hard to break fluid), basically unbreakable. My Sears Craftsman garden tractor has been towing a way over loaded garden cart for 26 years, albeit carefully....

 

[North Idaho Wolfman]

No you're not going to damage the engine or the transmission one bit running grades.

Treat the fuel, it might or might not help.
You may need to do more work to get it to start easier.