the R50 series Deutz has 1. head temp on #1 cylinder next to flywheel. It is not an on /off switch but operates between a certain ohm range. It will be the first to tell one it is overheating. 2. there is a temp sensing sending unit around the oil filter base - this is your temp gauge on rh side. 3. There is a warning light for the overhead for the temp that screws in the bottom of the oil pan - it is wired in sequence with the fan belt switch and oil pressure.
Keep the fins blown off in the cylinder and the oil coolers and intecooler. Between the turbo and the push rod tubes there is a plate that covers the tubes - remove this cover - it can be cut in two pieces to ease service, and blow out around push rods once every 200 hours or so or once a season. The big item is the oil cooler - it is right beside the oil filter. Blow or wash out from bottom up the top down when oil temp seems a bit high. Finally look at the blower fan -early OEM's were not 'nitrided'
or hardened aluminum like the expensive replacements are - I wish we could find some standard fans as these unit are now mostly lower hour use machines - and if the edges of the fins get thin - paper thin - they WILL NOT keep the engine cool.
Hope this helps.

 

Picked corn all day today with my R-50. Oil Temp barely got to 1/4. I blow off the engine and oil coolers every time I grease the machine which is about every morning. Also mine is extremely fuel efficient. I probably burning about a gallon an acre with an 830 head in 120 bushel corn.

 

I'm thinking I have some electrical gremlins - my oil temp guage isnt working and my oil pressure light is intermitant -- I'm gonna start checking the 3 senders on the oil pressure light -- figure as long as its not the fan belt switch i can trouble shoot it easily - fan belt looks new and in great shape but we'll see how that checks out. Also my head temp light would come on - and the engine was cool enough to lay my hand on - so im thinking i have some bad connections. When the head light was on (supposed to be 400 deg) my digital thermomitor was right at 170 on outside of jugs -- shut engine off and pulled shields and the temp was 170 on the jugs themselves - right after it was shut down it was 160.

 

check the engine harness - it is on the floor just in front of the alternator - major plug 2.5" X1 " approx best I can remember. This can get corroded as it is not a weatherpac type connector. Cann effect eng tach reading as well.