The thermostat is replaced in case of violation of the thermal regime of the engine, when the engine either overheats (the thermostat valve is stuck in the closed position) or does not heat up enough (the thermostat valve is stuck in the open position).
When checking the thermostat on a car after starting a cold engine, the bottom hose from the radiator should remain cold for some time, and then (after the coolant temperature reaches 89˚ C) heat up quickly, which indicates the beginning of the circulation of the coolant in a large circle .
To dismantle the thermostat, drain the coolant (article - Checking and replacing the Renault Duster engine coolant ).
We show the removal of the thermostat on the F4R engine, on the K4m engine we remove the thermostat in the same way.
Without disconnecting the hoses from the nozzles of the thermostat cover, with a head of 10, unscrew the three bolts securing the thermostat cover (the supply hose is removed for clarity)
Remove the cover from the thermostat housing
Remove the thermostat from the socket in the housing
The connection of the thermostat to the housing and cover is sealed with a rubber gasket.
If the gasket is damaged or has lost its elasticity, it must be replaced with a new one.
To check the thermostat, we lower it into a vessel with water.
We heat the vessel, while stirring the water and controlling the beginning of the opening of the thermostat valve with a thermometer.
The valve stem should begin to extend at 89°C, indicated by the number 89 on the end of the thermostat bottle
At a temperature of 95±2˚С, the valve should open completely - the stem stroke should be at least 8 mm.
Install the thermostat in reverse order.
Pour liquid into the cooling system and bring the liquid level in the reservoir to normal.
Removing the water distributor
We remove the water distributor to replace the sealing gasket in the connection of the cylinder head with the flange of the thermostat housing, as well as when repairing the cylinder head.
Draining the coolant from the cooling system
Remove the thermostat as described above.
Remove the air intake and the engine air path resonator.
Disconnect the wiring harness block from the coolant temperature sensor
Using the blade of a flathead screwdriver to pry the plastic bracket of the wiring harness
We take out the piston 2 from the hole 1 of the thermostat housing (shown with the gearbox removed)
Using an 8 spanner wrench, unscrew the bolt that secures the bracket for the heater hoses of the wiring harness to the thermostat housing.
We compress the ends of the fastening clamp with sliding pliersi of the hose for supplying fluid to the heater radiator, move the clamp along the hose and remove the hose from the nozzle of the thermostat housing
With a head of 8, unscrew the nine bolts securing the thermostat housing to the cylinder head
Removing the water distributor
Remove the gasket
In the body and the gasket there are channels for oil and coolant.
We install a new gasket and tighten the nine bolts in the sequence shown in the figure.
Tightening torque - 10 Nm.