I just bought an 82 Rabbit Diesel 1.6L. My questions are many but let me start with the most serious. The guy I bought it from said it runs hot so he straight wired a toggle switch to the fan so you can run it all the time. Even with this mod it still runs hot. What should I check for first? (thermostat?) Next serious question, my buddies say its normal for an old diesel but is there anything I can do to help the vibration when the car is idling? Is this just part of owning a diesel or can you get some sort of upgraded motor mounts to calm downt he vibrations? Any help on these subjects would be greatly appriciated.

The thermostat would be the easiest & cheapest place to start. The mounts, particularly the one at the fron timing belt, were prone to collapse & vibrate.

if the engine vibrates excessively the cam timing may be slightly retarded (i just resolved this issue with my own engine). it can be advanced up to five degrees measured on the crank shaft (or 2.5 measured on the camshaft, but it is easier to measure this on the crank). it certianly won't be the most smooth running engine ever, but things in the car won't shake as bad with the cam advanced, and the intake noise will be somewhat more quiet as well (due to the intake valve closing before reversion can occur -- that's my best guess).

while you are replacing your thermostat you should check the operation of the fan swich. replace it if you think it may be inoperable; that is the safest approach with a diesel.

Run the engine until is is warmed up good, then shut it off and disconnect the power to the fan (so it can't turn on unexpectedly and take off your fingers) and feel the radiator. Any area that is cold has a clogged water tube.

I just bought an 82 Rabbit Diesel 1.6L. My questions are many but let me start with the most serious. The guy I bought it from said it runs hot so he straight wired a toggle switch to the fan so you can run it all the time. Even with this mod it still runs hot. What should I check for first? (thermostat?) Next serious question, my buddies say its normal for an old diesel but is there anything I can do to help the vibration when the car is idling? Is this just part of owning a diesel or can you get some sort of upgraded motor mounts to calm downt he vibrations? Any help on these subjects would be greatly appriciated.
I had one running hot and found out the small hole on top of the radiator that attaches to the line that goes to the plastic resovour was plugged. I carefully drilled it out and was in business. You should see water squirting into this plastic resovour through the line when running and cap off.