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[Datsun 1200 encyclopedia]

Head gasket

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Category: Engine Mechanical

The Datsun 1200 cylinder head gasket fit A12 and A10 engines. Aftermarket gaskets vary in material and size of cooling holes. Aftermarket gaskets may come with oversized bore holes.



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Also See:
* Changing Head Gasket
* Tune-up
Nissan recommends re-torquing the head gasket bolts ever twenty-four months (every two years):

1972 USA Owners manual (Page 34 ... ):

th_00_cover.jpg   th_34.jpg
Retighten cylinder head bolts, manifold nuts & carburetor securing nuts.

slight weeping leak — oil is weeping out of the gasket, dirtying the cylinder block below. Solution: replace gasket
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Most A-series head gasket are 1.6 mm thick. Some are 1.2 mm thick. So which brand you buy can make a slight difference.

The A12GX Engine used a thin gasket to achieve its 10:1 compression ratio.

Nismo MLS gasket is 0.5 thickness for improved quench, thus slightly more power.

See also: Quench#Gaskets

Head Set

A Head Set gasket kit includes all you need to change the head:

* Cylinder head gasket
* Valve stem seals
* Rocker cover gasket
* Gasket-manifold to cylinder head

it may include the following:

* thermostat gasket
* intake-to-exhaust manifold gasket (heat riser gasket) 
* oil cap packing (gasket)
* fuel pump gaskets
* Victor HS3602
* FEL-Pro HS21181PT 
* ROL HS32060

Blown Gasket

Coolant leaking into the oil pan, causing "milkshake" to be visible on the oil cap and dipstick.
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Double-check by looking at the dipstick

  • Cap milky, dipstick oil clear: This is caused by condensation, not by a bad head gasket
  • Cap milky, dipstick oil milky: oil-water mixture due to bad head gasket

A coolant-system leak test can be performed. However, on an A-series engine, practically the only way this can happen is through the head gasket (gasket failure between coolant hole and oil drain-back hole). On some engines it can have other causes.

Removing the spark plugs: you can see that one plug color differs from the other. There is a problem, but it is not necessarily the head gasket
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After the head is removed, the final inspection can begin
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When a head gasket is blown out (partly missing) between cylinders it is obvious, and the engine will run on "two cylinders" (barely run, if at all). Engine compression test will show this as two cylinders reading zero pressure.
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But head gaskets more often fail in a less obvious manner -- they lift up enough to allow compression to leak past, causing low compression. An Engine compression test will find this.

Sometimes you can see a "trail" were pressure leaked out of cylinder
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A more rare failure is of the oil or water passage. The engine will still run perfectly, but oil will leak or coolant will be lost. A Cooling System Pressure Test can often pinpoint the diagnosis.

Looks like oil leaked onto the gasket during removal. Not a sign of a bad gasket
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Sometimes one cylinder is perfectly clean. This means that engine coolant leaked into the cylinder and 'steam cleaned' the piston top — and sign that the head gasket has leaked
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Turbo Boost/Supercharger

Standard head gasket works fine to at least 15 psi boost. Over 15psi, consider going to a copper head gasket and orings, which requires a special finish and coatings.


Spacers between the block and head gasket are useful for racing with Forced Induction. It reduces the compression ratio, but it allows more boost to be applied, which can be tuned for more power. The downside is less power at part throttle, so it is not recommended for a street engine.

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custom order
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H1000 was the original gasket.

#October 1971 Gasket material change

#H3900 is the revision from May 1972. It made the cylinder openings closer in size to the 73mm bores, in order to reduce emissions. Bonus, it helps HP a tiny bit too.

#H3925 was the late 1972 revision that reduced risk of oil leaks by using an O-ring seal.


H3925 was the July 1972 revision that reduced risk of oil leaks by using an O-ring seal.

Bulletin Number: TS72-77
Date: August 3, 1972
Classification Number: EN72-011
Section: Engine
Models: (K)LB110

Production Change: The modification listed below have been made for better oil sealing

Beginning Engine Serial Number: A12-127535

Beginning Production Date: July, 1972

Note: These number are part of the new number series. See TS72-62 for more information

1. The exhaust valve O-rings and O-ring grooves have been eliminated (See Figure 1)
2. An O-ring has been inserted in the oil hole in the mating surface of the cylihder head with the cylinder block (See Figure 2) The head gasket has also been changed
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Parts Information
Head gasket kit (gasket & O-ring)
New Part Number: 11044-H3925
Former Part Number: 11044-H3900
Interchangeability Yes

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Bulletin Number: TS72-44
Date: May 22, 1972
Classification Number: EN72-007
Section: Engine
Models: A12,L16

Combustion chambers of the 1972 model A12 and L16 engines were redesinged to reduce hydrocarbon emission to a minimum and the configuration of cylinder head gaskets was changed. The opening in the cylinder head gasket at bore location is made smaller in diameter to reduce the quench area to a minimum and thus prevent incomplete combustion of the air-fuel mixture. Because of this change, the correct gasket must be used for replacements on 1972 engines

Beginning Engine Serial Number & Part Number
L16-203416 11044-N2211

A12, not interchangeable
L16, 1972 to earlier models, yes, earlier models to 1972, no

October 1971

Bulletin Number: TS71-45
Date: October 1, 1971
Classification Number:
Section: Engine
Models: (K)LB110

Production Change: On the A12 engine, the currently used oil-soaked cylinder head gasket has been replaced with a dry gasket of the same type

Beginning Engine Serial Number: A12-485141

Parts Information: The part number has not changed
1971 and earlier Cylinder Head Gasket 11044-H1000
1972 Cylinder Head Gasket 11044-H3900
Interchangeability Yes

Part Numbers

11044-H3925 GASKET-CYLINDER HEAD B110 A12 USA 0671- $57 USD > 11044-H3900
11044-H3901 GASKET-CYLINDER HEAD B210+B310 A12 JAP 
11044-H1025 B110 (from '72-5) > 11044-H1000 > 11044-18004
* 11045-H1000 RING "O" (from '72-5)
11044-H1025 B210 from '75-5
11044-18004 GASKET-CYLINDER HEAD B10 A10 > 11044-18002 <> 11044-18001 <> 11044-18000
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A10 PULSAR 1000 BN10 988cc 1978-ON
A10 SUNNY 1000 B10,B20 1000 1966-1970
A12 SUNNY 1200 B110,B210,C20  1171cc 1970-73.3  
A12 SUNNY 1200 B210 1973.4-75  
A10 CHERRY 1000 E10, F10 988 1970.10-73.9  
A12 CHERRY 1200 PE10, F10 1171cc 1972-78  
11044-18004 GASKET-CYLINDER HEAD A12 superceeded 
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11044-H1000 GASKET-cylinder head B110, B210 to '75-4
11044-H1025 B210 from '75-5
11044-H3900 GASKET-CYLINDER HEAD A12 0671- 
A10 PULSAR 1000  BN10  988cc  1978-ON  
A10 SUNNY 1000 B10,B20 1000 1966-1970
A12 SUNNY 1200 B110,B210,C20  1171cc 1970-73.3  
A12 SUNNY 1200 B210 1973.4-75  
A10 CHERRY 1000 E10, F10 988 1970.10-73.9  
A12 CHERRY 1200 PE10, F10 1171cc 1972-78  
11044-H2300 A12GX, A12T
11044-H2301 [thinner?] A12GX, A12T
11044-H2325 A12GX from '72-6
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11044-H2325 A12 GX from '72-6 > 11044-H2300 
* 11045-H2300 RING "O" (from '72-6)
11044-H2301 A12T B210 [thinner?]

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GX Metal

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Nissan Competition

Nissan Competition
Competition198438.jpg* 11044-M0821 COMPETITION HEAD GASKET
Gasket has a bore diameter of 79mm/3.11", an uncrushed thickness of 0.8mm/0.032" and displaces 3.9cc's.

Nismo head gaskets for Nissan A series motor A12,A13,A14,A15 Engine

11044-M0822 t=0.8 79.0 mm bore diameter 
11044-M0823 t=0.6 80.0 mm bore

11044-M0822 79mm diameter bore
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