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Revision as of 22:09, 13 November 2012

Datsun 1200 uses a traditional 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.

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1 Cooling Thermostat
2 Thermostat Housing

Cooling Thermostat

Replacement

Replacement of the thermostat is called for when:

the engine runs too hot and other causes have been out. See Cooling System Diagnoses
the engine runs too cold

Put a bucket under the radiator fan to catch spilled coolant
Loosen the clamp on the hose at the water outlet
Twist and pull the hose off the outlet
Remove the two fastening bolts
Scrape all traces of gasket off water outlet and cylinder head face
- be careful not to nick the aluminum of the gasket faces
Fit thermostat into engine, then gasket, then housing and tighten moderately. The gasket goes against the housing (not the head).
Top up coolant
Rinse spilled coolant off engine and body with water
After engine has been fully warmed up, and cooled down, top up coolant again.

Be sure to fit thermostat with spring facing into engine

WARNING: Due to air pockets, the coolant level usually drops down and the engine can easily overheat if not monitored for a few days after changing the thermostat.

Temperature

It is not unusual with any 10-year old stock radiator for the temperature to rise during summer. If this occurs with your Datsun, don't panic. The engine can run all day close to the "H" mark.

DO NOT let it go onto the H mark. Pull over immediately if it goes past the H mark. Don't wait 30 seconds, it could be too late.

Typical Temperature

If this worries you, fit a slightly larger radiator to provide more cooling than Datsun provided with the 1200s.

According to Owner's Manual: Water Temperature Gauge,
the engine will run "satisfactorily" in this range:

1972 USA Owners manual (Page 10 ... ):

For most types of driving, the pointer will hover about halfway. However, the engine will run satisfactorily when the pointer is at any position in the middle range.

TIP: Use the stock engine-drive fan. Electric fans are notorious for failing to cool the radiator in stop/go traffic. Of course an electric fan can work well, but many don't.

What is the correct temperature the engine should run at?
Primarily, this depends on the thermostat. The engine can run fine at a variety of temperatures. You can get different temp thermostats, and the coolant should stay steady at that temperature.

Datsun factory options were:

* THERMOSTAT 170 F (75.5c optional, for tropical use)
* THERMOSTAT 180 F (82 c, for standard use)
* THERMOSTAT 190 C (88 c, optional for winter)

These three thermostats were mainly because of the heater. 170 for hot climes so the room heater won't put out much heat, 190 for cold climes so the heater puts out more heat.

180 is recommended for all street cars, it will keep the oil at optimum temperature (oil runs about 20 degrees hotter than the coolant). A guy at the oil company told me 180 is ideal for the oil working the best. He went through training for Mobile I think it was and they were formulating oil for 200 degrees, which works out to be 20 degrees warmer than the coolant for most engines. Maybe it's changed now but it won't be colder as engines now run hotter than ever. If anyone has documentation for this please add it here.

160-degree is favored by some for drag racing as they tune the carbs for cold dense air, or for use with low octane fuel. But EFI computers don't run well at cold temps nor does the oil, and cold temps mean more engine wear. Cold temps are not recommended.

But won't I make more HP with a colder thermostat?
Not if your carburetor jetting is stock -- it expects warmer less dense air. And when you floor the accelerator pedal, the air cleaner hot air duct opens up letting only cooler air in, and the stock Hitachi compensates via the power valve. Those clever Datsun engineers had it covered.

Many cars use a 195 F degree thermostat along with a 14 lb. radiator cap to raise the boiling point. A radiator is more efficient at higher temperatures, because the temperature differential to the air will be greater, thus shedding heat faster. In turn airflow can be reduced which increases aerodynamics.

After the thermostat, the radiator is the next factor. If your temp. stays steady except on hot summer days (which is normal), you can use a bit larger replacement radiator and it will stay steady even during temperature peaks. Use either a new unit, rebuilt unit, or a good used unit from a B210 or B310, which are larger than the 1200 radiator.

See Radiator.

Thermostat Types

Newer Type - advanced type with 'jiggle' valve. The jiggle valve is used to "shorten the warm up period" (Nissan Service Bulletin No. 188 Introduction of New Datsun B210, 1973).

Thermostat Testing

Test it like this:

Thermostat Part Numbers

Buy at http://www.rockauto.com

Gaskets

There are various gaskets.

4-bolt gaskets work on a 2-bolt housings.

2-bolt: 11062-18000 GASKET-WATER OUTLET
3-bolt: 11062-M3001 GASKET-WATER OUTLET
4-bolt: 11062-H7201 GASKET-WATER OUTLET

Cooling Thermostat

Cooling Thermostat. $7-$16

Nissan Part Numbers

B10, B110 and early B120:

21200-78500 THERMOSTAT 82 C
21200-A3001 THERMOSTAT 82 C EVAPO systems
21200-78502 THERMOSTAT 76.5 C (optional, for tropical use)???????
21200-A3005 THERMOSTAT 88 C (optional, winter)

Late B120, early B122:

21200-H7800 82 C 7602-8503
21200-V0105 88 C 7908-8109?????????
21200-V0205 88 C 8110-8503?????????

Late B122

2100-G3100 82 C 8504- ???????
2100-G3160 82 C 8504- ??????????
2100-V0206 88 C 8504- ????????

Interchange

For standard B110 180-degree thermostat: Rockauto.com

STANT 13858 with jiggle pin
STANT SuperStat 45858 with jiggle pin
GATES 33478 with jiggle pin
GATES 33478S Premium with jiggle pin
BECK/ARNLEY 1430685
BECK/ARNLEY 1435685 Fail-Safe
Prestone 391-180
Prestone 752-180

Dimensions:

2 1/8" diameter
29/32" high hot side x 29/32" high cold side

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

Thermostat Housing

Nissan calls the thermostat housing the "Water Outlet".

11062-18000 GASKET-WATER OUTLET

11060-G0300 OUTLET-WATER B110 JDM, USA
11060-H7000 OUTLET-WATER B110 USA MANUAL from 0373
- Has boss for temp switch
  22120-U2001 ASSY-SWITCH WATER TEMP from 0373

A-engine Variations

There are a number of different type for A-series engines.

2-bolt Type -- as used by early engines, and some late engines
3-bolt Type -- newer engines
4-bolt Type -- newer engines

It further breaks down:

2-bolt Type -- as used by Datsun 1200
- B10/B110 Type, outlet points 180 degrees
- Late B110 USA -- with boss for thermo switch
- B210/B310 Type - Outlet points 225 degrees
3-bolt Type
- with accessory mounting bosses
4-bolt Type -- as used by some newer engines
- with accessory mounting bosses and Air fitting
- with accessory mounting bosses (forward) and Air fitting

2-bolt Type Thermostat housings attaches radiator hose at:

B10/B110: 9:00 o'clock (180 degrees)
B210/B310: 10:30 o'clock (225 degrees) to clear alternator belt

of high-mounted alternator

Head Mating Surface

Starting with the 1974 redesign, all A-series cylinder heads feature alternator on right side of engine. This necessatated adding a bolt hole to the front of the head next to the water outlet. This means the water outlet was raised up so as to not cover the bolt. This in turn means the radiator hose location is different, even though the first yeat B210 radiator is otherwise nearly identical to the B110.

Head Mating Surface: 1974-up engine w/o Air passage

Head Mating Surface: 1974-up engine with Air passage

Housing Part Numbers

NOTES:

CAL = California
CAN = Canada
FED = USA, except California
GFU = 5-speed Round-port A14 engine
JDM = Japan Domestic Market
Gasket is also called "WASHER-JOINT WATER OUTLET"

The 4-bolt gasket works on a 2-bolt housing.

2-bolt Type

The 2-bolt type is used by B10 and B110. It is also used by some B210/B310 engines that do not have an Air passage in the cylinder head.

11062-18000 GASKET-WATER OUTLET

11060-18000 OUTLET-WATER B10
11060-G0300 OUTLET-WATER B110 JDM
11060-G0300 OUTLET-WATER B110 AUTOMATIC USA
11060-G0300 OUTLET-WATER B110 MANUAL from 0273 USA
11060-H7000 OUTLET-WATER B110 MANUAL from 0373 USA
- Has boss for temp switch:
  22120-U2001 ASSY-SWITCH WATER TEMP from 0373

B110 housing and original fittings

11062-H7201 GASKET-WATER OUTLET

11060-H5000 OUTLET-WATER B210 A13 USA 1974, A12 JDM early
11060-H5000 OUTLET-WATER B310 A12,A13,A14,A15 JDM 8011-
11060-H5000 OUTLET-WATER B120 A12 -8910
11060-H5000 OUTLET-WATER B310 A12A CAL from 0879
- 11062-H7201 GASKET-WATER OUTLET

You can see how on newer engines, the alternator bracket bolts next to the outlet. This requires the outlet at 45 degrees up so the bolt is uncovered.

11060-G2500 OUTLET-WATER B120 A12 8910-
- 11062-H7201 GASKET-WATER OUTLET -9202
- 11062-18000 GASKET-WATER OUTLET 9202-

3-bolt Type

The 3-bolt water outlet was used in newer engines that do not have an air port in the front of the cylinder head -- and that do not have the alternator bracket bolted to the front of the head. In this case, the outlet can exit more to the side, even covering the 4th bolt hole.

11062-M3001 GASKET-WATER OUTLET

11060-M3001 OUTLET-WATER B310 JDM -7812 A12 S,K; A14 V
11060-M3001 OUTLET-WATER B310 A14,A15 FED

4-bolt Type

All engines with Air passage in the cylinder head require a 4-bolt housing and gasket. Some newer engines without Air system also use the 4-bolt kit.

Air Pump Type - bosses up

11062-H7201 GASKET-WATER OUTLET

11060-H7201 OUTLET-WATER B210 A14 USA
11060-H7400 OUTLET-WATER B210 A14 FED GFU from 1276
11060-H7400 OUTLET-WATER B210 A12 late, A14
11060-H7400 OUTLET-WATER F10 A14 USA

Air Induction Type - Bosses Forward

11060-H9100 OUTLET-WATER B310 A14,A15 CAL,CAN
- 11062-H7201 GASKET-WATER OUTLET B310 A14,A15 CAL,CAN
11060-H9100 OUTLET-WATER B310 A12A from 1278
- 11062-H7201 GASKET-WATER OUTLET A12A CAN from 1278
- 11062-M3001 GASKET-WATER OUTLET A12A FED from 0879