How to replace the cylinder head gasket on the Great Wall Safe

The Chinese SUV Great Wall Safe is equipped with a GW491QE gasoline engine. This engine is a modified licensed version of the 4Y unit, which was once installed on Toyota Camry cars. The Chinese “finished” the gas distribution mechanism and the cylinder head (cylinder head) in it. The cylinder block and crank mechanism remained the same.

Cylinder head gasket in the GW491QE unit

One of the main vulnerabilities of the GW491QE engine is the cylinder head gasket. And this is not the fault of the Chinese - its breakdown was also found on the original Toyota engine. Most often, the flow begins in the area of ​​\u3b\u4bthe XNUMXrd or XNUMXth cylinder.

The gasket is installed between the cylinder block and the head. Its main purpose is to seal the combustion chambers and the water jacket through which the coolant circulates.

Damage to the cylinder head gasket is fraught with mixing of working fluids, which leads to engine overheating, poor lubricant quality and accelerated wear of engine parts. It may be necessary to replace the engine oil and antifreeze with flushing the cooling system and lubrication system. There may also be engine malfunctions and excessive consumption of gasoline.

The cylinder head gasket resource of the Great Wall Safe engine under normal conditions is approximately 100 ... 150 thousand kilometers. But problems may well arise earlier. This can be caused by malfunctions in the cooling system and overheating of the unit, improper installation of the head, or marriage of the gasket itself.

In addition, the gasket is disposable, and therefore, each time the head is removed, it must be replaced with a new one, regardless of the time of use. Also, at the same time, it is necessary to change the fastening bolts, since their parameters no longer meet the necessary requirements for tightening with the necessary force.

The cylinder head gasket for the GW491QE engine has an article number 1003090A-E00.

You can purchase it in the Chinese online store. You can also select others here.

Instructions for replacing the cylinder head gasket with Great Wall Safe

From the tools you will need a set of long narrow socket heads, a wallpaper knife, zero-skin (you may need a lot), a torque wrench, various cleaners (kerosene, flushing oil, and others).

Work is best done on a lift or viewing hole, as you will need access from below.

As a preparatory step before removing the cylinder head, take the following three steps.

1. Turn off the power by disconnecting the negative cable from the battery.

2. Drain antifreeze. If the engine is hot, wait until the coolant has cooled to a safe temperature to avoid burns.

You will need a container with a volume of at least 10 liters (the nominal amount of fluid in the system is 7,9 liters). It should be clean if you do not plan to fill in a new coolant.

Drain the working fluid from the cooling system through the drain cocks of the radiator and cylinder block. Remove antifreeze from expansion tank.

3. During engine operation, gasoline in the fuel supply system is under pressure. After stopping the motor, the pressure gradually drops over several hours. If it is necessary to carry out work immediately after a trip, make a forced release of pressure. To do this, disconnect the chip with the fuel pump power wires, then start the engine, leaving the gear selector in neutral. After a few seconds, the remaining fuel in the rail will run out and the engine will stall. Don't forget to put the chip back in place.

Now you can proceed directly to disassembly.

4. Before removing the head itself, you need to disconnect everything that will interfere with its dismantling:

- the upper inlet hose of the radiator and the hoses of the heating system;

— duct nozzle;

— a branch pipe of the muffler of an exhaust manifold;

- fuel hoses (disconnect and plug);

- accelerator drive cable;

- water pump drive belt;

- power steering pump (you can simply unscrew it without disconnecting it from the hydraulic system);

— wires with candles;

- disconnect the wires from the injectors and sensors;

- remove the cylinder head cover (valve cover);

- Remove rocker pushers.

5. Gradually, in several passes, you need to loosen and unscrew the 10 main bolts. The sequence of unscrewing is indicated in the figure.

6. Give 3 additional bolts.

7. Remove the head assembly.

8. Remove the old cylinder head gasket and carefully clean the surfaces from its remnants. Close the cylinders to keep debris out.

9. Check the condition of the mating planes of the head and cylinder block. At any point, the deviation of the plane from the gauge should not exceed 0,05 mm. Otherwise, it is necessary to grind the surfaces or replace the BC or head.

The height of the cylinder block after grinding should not decrease by more than 0,2 mm.

10. Clean cylinders, manifolds, head from carbon deposits and other dirt.

11. Install new gasket. Install the cylinder head.

11. Apply some engine grease to the head mounting bolts and screw them in by hand. Then tighten according to a specific procedure.

Please note: Improper tightening will significantly reduce gasket life.

12. Everything that was removed and turned off, put back and connect.

Tightening the cylinder head bolts of the Great Wall Safe engine

The procedure for tightening the mounting bolts is usually described in the accompanying documentation, which should be included with the gasket. But sometimes it is missing or the instructions are quite difficult to understand.

The tightening algorithm is as follows.

1. Tighten the 10 main bolts to 30 Nm in the following order:

2. Tighten to 60 Nm in the same order.

3. Tighten to 90 Nm in the same order.

4. Loosen all bolts 90° in reverse order (as in disassembly).

5. Wait a little and tighten to 90 Nm.

6. Tighten the three additional bolts to 20 Nm.

7. Next, you need to assemble the engine, fill in antifreeze, start it and warm it up until the thermostat trips.

8. Turn off the engine and leave to cool for 4 hours with the hood open and the cover of the expansion tank of the cooling system removed.

9. After 4 hours, open the valve cover and loosen all 13 bolts by 90°.

10. Wait a few minutes and tighten the main bolts to 90 Nm, the additional bolts to 20 Nm.

After approximately 1000...1500 kilometers, repeat the last broaching step. Don't neglect this if you don't want to get into other similar troubles.