Datsun 1200 uses a tradition pellet-type engine cooling thermostat. It regulates temperature by closing when cold, to keep hot water in the engine, and opening when hot, allowing the coolant to flow to the radiator to shed heat.
Temperature
It is not unusual with any 10-year old stock radiator for the temperature to rise during summer. If you have this, don't panic. The engine can run all day close to the "H" mark. Just don't let it go over that. If you are worried, replace the radiator.
Use the stocko fan. Electric fans are notorious for failing to cool the radiator in stop/go traffic.
What is the correct temperature the engine should run at? Primarily, this depends on the thermostat. You can get different temp thermostats, and the coolant should stay steady at that temperature:
- 160 degree
- 180 degree
- 212 degree
160-degree is good for drag racing, or for use with low octane fuel. 180 is recommended for all street cars, it will keep the oil at optimum temperature (oil runs about 20 degrees hotter than the coolant). 212 degree is only run on emission-control cars along with a 14 lb. radiator cap to prevent boiling.
After the thermostat, the radiator is the next factor. If your temp. stays steady except on the hottest summer days it seems you need a replacement radiator, either a new or rebuilt stock unit, or a larger used unit (from a B210 or B310).
Thermostat Testing
Test it like this:
Part Numbers
Cooling Thermostat. $7-$16
Honda 1994 - 1996 PASSPORT
ISUZU 1989 - 1994 AMIGO, 1992 IMPULSE, 1981 I-MARK, 1981 - 1995 PICKUP, 1985 - 1989 I-MARK, 1991 - 1997 RODEO, 1988 - 1990 IMPULSE, 1984 - 1991 TROOPER
NISSAN , 1971 - 1973 1200 , 1980 - 1986 720 PICKUP , 1977 - 1988 200SX , 1977 - 1981 810 , 1979 - 1982 210 , 1974 - 1978 B210 , 1974 260Z , 1986 - 1989 D21 PICKUP , 1975 - 1978 280Z , 1976 - 1978 F10 , 1979 - 1982 280ZX , 1982 - 1984 MAXIMA , 1979 - 1982 310 , 1987 PATHFINDER , 1971 - 1973 510 , 1983 PULSAR , 1978 - 1981 510 , 1983 - 1989 PULSAR NX , 1971 - 1972 521 PICKUP , 1982 - 1988 SENTRA , 1973 - 1976 610 , 1982 - 1989 STANZA , 1972 - 1979 620 PICKUP , 1987 - 1988 VAN , 1974 - 1977 710