When changing the timing belt - PLEASE make sure it goes on correctly, its just sad to see the number of nissan CD20 belts misaligned causing engine damage...
Before taking off the original belt - apply some yellow paint on the old belt where the pulley marks meet them (engine should be at perfect TDC) - do this for both.
now count the teeth between the marks - on a CD17 the count is 37th tooth and the pump is 21st tooth, (CD 20 is I belive 39th tooth).. If you dont do this you will never find proper timing - this is Nissans original timing belt installation guide (original Nissan timing belts come with marks on them). Once installed with the drive side taught (loosen tensioner and tighten again, rotate engine so you see TDC align on belt once again - loosen and tighten tensioner - your belt will be tensioned properly this time)
While at this task - buy some nice coolant, Caltex, ZIC, Mobil, Seiken and buy a gallon distilled water from the medical or chemical market near Denso Hall, prepare and replace all old coolant with this new mixture. When you start up your engine be sure to purge any air from it, by parking upslope (or jack under the car) and loosening the bleed valve or slightly loosening the cylinder head upper radiator pipe so air can escape (remember to have your heater at max too), slowly pour the coolant and keep on topping till it settles or starts to dribble out of the pipe fitting. tighten, top up again, pump the pipes by hand to remove any stuck air while slightly revving and you'll be good (your cooling fans may also kick on as the Tstat opens up) - btw the cooling fans are also module controlled hence coolant keep the sensor in top shape. Dont try to fiddle with it, this one module also runs the temp gauge.