Withdrawal
Pic. 7–1. Water pump and thermostat for cars with 2.8L petrol engines: 1 - thermostat; 2 - sealing ring; 3 - thermostat housing; 4 - bolt, 10 Nm; 5 - gasket; 6 - water pump; 7 - bolt, 10 Nm
The thermostat is located in the housing (pic. 7–1), mounted on the engine block.
Drain the coolant.
Remove the V-ribbed belt and its tensioner.
Remove the left and right toothed belt covers.
Using a marker, chalk or paint, mark the direction of rotation of the toothed belt.
Loosen toothed belt tension. Slightly turn the crankshaft in both directions to loosen the toothed belt tension and remove the toothed belt from the tension roller and the right camshaft pulley.
To protect the toothed belt from coolant, cover it with polyethylene.
Pic. 7–2. The location of the bolts of the thermostat housing
Unscrew the two bolts and remove the thermostat housing from the front of the cylinder head (pic. 7–2).
Remove the O-ring and thermostat from the cylinder head. Check the functionality of the thermostat.
Installation
Pic. 7–3. The correct location of the thermostat on gasoline engines 2.8 l
Install the thermostat in the cylinder head so that the bleeder valve is at the top (pic. 7–3).
Install the thermostat housing with a new sealing ring and secure with bolts, tightening them with a torque of 10 Nm.
Install the toothed belt onto the camshaft pulley.
Install poly V-belt.
Pour coolant into the cooling system.
Start the engine and check the cooling system for leaks.
Checking the functionality of the thermostat
Pic. 7–4. Operating positions of the thermostat valve: a - the valve is closed; b - valve open
Measure length A closed thermostat (pic. 7–4).
You can approximately check the thermostat's performance as follows: hang it on a thread in a glass vessel filled with water and heat the water to a boil. When the water boils, the thermostat valve should open. Otherwise, replace it.
The opening temperature of the thermostat valve is marked on its body.
When the thermostat is heated to the boiling point of water, the length b open thermostat with an open valve must be longer than the length A with closed valve 7 mm (see fig. 7–4).
A thermostat whose valve does not close when the water cools should also be replaced.
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