78Thermostat & Water Temperature Sensor Adapter Kit for NA6CE

Supported MIATA model:NA6CE ('89 early model / 1.6L)

(Photo 1) Left:Adapter for water temperature gauge
Center:Maruha 78 Thermostat Right:Inner ring

Maruha 78 Thermostat, which is one of our hit products, has remarkable performance with the high stroke rod in 10 mm and the large-diameter valve.

The product's valve begins opening at 78 degrees of Celsius and completely opens at about 90 degrees of Celsius. It allows the radiator to increase the capacity with superb water circulation to cool down the engine.
The 78 Thermostat is an excellent product, but unfortunately, it cannot be used for NA6CE model because of the interference in the thermostat housing.

Maruha 78 Thermostat Kit makes it possible to install our 78 Thermostat in NA6CE without any interference. To begin with, we will mention the background of developing the thermostat kit.

(Photo 2) The MIATA genuine NA6CE thermostat housing

The L-shaped metal housing is designed to set the thermostat in a vertical position.
Photo 2 shows the NA6CE thermostat housing designed to fit the thermostat onto the housing pipe.
The normal NA6CE thermostat's full length is shorter than that of the other genuine ones (Photo 3).

(Photo 3) The MIATA genuine NA6CE thermostat

If a thermostat longer than the genuine NA6CE housing is installed by mistake, coolant leaking might occur due to clearance between the thermostat body and the thermohousing.
For instance, when Maruha 78 Thermostat is arranged in the normal NA6CE thermostat housing, the red circle shows that clearance can be found between the thermostat and the housing (Photo 4).
The allowance causes the housing damages besides the fluid leaking.

(Photo 4) Unsuitable thermostat in the NA6CE thermostat housing
The clearance (red circle) can cause the coolant leaking and the damages on the thermohousing.

The bottom ribs of the NA6CE thermostat housing bring the interference to the thermostat (Photo 5).

(Photo 5) Bottom of the NA6CE thermostat housing
The ribs in the red circle cause the clearance.

The ribs are designed to allow the coolant fluid to flow smoothly through the housing as well as to maintain the strength of the housing body.
Furthermore, we found that the thermostat valve operating with the change of water temperature can be placed perfectly into the housing (Photo 6).
This fact enables to solve the problem.
If there is no allowance, Maruha 78 Thermostat is available in the NA6CE model.
Arranging an adapter between the ribs and the thermostat avoids the interference without any troubles.

(Photo 6) Installing Maruha 78 Thermostat without an adapter in the NA6CE thermostat housing
The top of the thermo valve can be set in the housing without floating, even though there can be seen several clearances between the thermostat body and the housing.

The adaptor of Maruha's thermostat kit provides Maruha 78 Thermostat without interference in the ribs on the bottom of the thermostat housing.
The following shows how to install Maruha 78 Thermostat in the NA6CE model.

[How to Install]

  1. Put the adapter on the thermostat housing.
  2. Install Maruha 78 Thermostat above the adapter.
  3. Place the inner ring over the thermostat.

* Assemble the parts in the right order to avoid damages.

The inner ring preventing the movement of the thermostat has a slit for guiding the water temperature gauge to the right position.
The gauge should be set above the thermostat body.
In case the gauge is fixed under the thermostat, it is possible to interfere with the rod spring when the thermostat shrinks.

Maruha 78 Thermostat Kit includes a 1/8 NPT female bolt for the water temperature gauge.
Please confirm the bolt sizes for your gauges before purchasing.

The product should be installed by a professional.

For more information about Maruha 78 Thermostat, please visit Maruha 78 Thermostat page.


Maruha Motors Co., Ltd.
Ushizuma 2095-6, Aoi-Ward
421- 2106 Shizuoka city, Shizuoka prefecture
TEL: 0081-54-294-0076
FAX: 0081-54-294-1312
E-mail: info@maruhamotors.co.jp