Engine volume 1.6 MPI, installed on cars Skoda Octavia of different generations (A5 and A7), is one of the most popular units in the VAG range. Despite the simplicity of the design and the absence of direct injection, this engine requires careful attention to the gas distribution system. Incorrect setting of the valve timing when replacing the belt can lead to serious consequences, including deformation of the valves.
Replacement process timing belt on the 1.6 unit (engine codes CWVA, CFNA, BGU, BSE) has its own technical features, which are often ignored by technicians. Many owners believe that it is enough to simply align the marks on the pulleys, but in reality, precise fixation of the crankshaft and camshaft is required. In this article we will look in detail at how to correctly set timing marksto avoid fatal errors.
Preparation for replacement and necessary tools
Before you begin disassembling the attachment, you need to make sure you have the specialized tools. A standard set of keys will not help here, since the shafts need to be firmly fixed at top dead center. You will need camshaft retainers and a snap ring for the crankshaft.
It is important to understand that the EA111 series engines (1.6 MPI) use double row timing belt, which works in tandem with a tension roller. The lack of a high-quality tool for fixing the shafts will lead to the fact that when removing the old belt, the shafts will spin and you will lose phases. This will make it impossible to reassemble correctly without disassembling again.
- ๐ ๏ธ A special camshaft clamp (bar) is a must-have tool for Skoda Octavia.
- ๐ง Crankshaft retaining ring (hex or pin) that locks the flywheel.
- ๐ฆ Powerful flashlight for inspecting marks on gears in hard-to-reach places.
- ๐งด Carburetor cleaner and new valve cover gasket.
Don't try to save money on the belt and rollers. Cheap analogues often do not maintain the declared service life, and jumping several teeth leads to disruption of the engine. For Octavia with a 1.6 engine it is critical to use a kit from trusted brands, such as ContiTech or Gates.
Setting the top dead center (TDC)
The first stage of work is to accurately align the marks on the crankshaft and camshaft gears. The engine must be cranked clockwise until the marks on the flywheel match the mark on the gearbox housing. This is the basic position from which the entire procedure begins.
After the flywheel is aligned, it is necessary to check the position of the camshafts. There are special cut-out marks on the rear timing drive cover. They should fit perfectly with the edges of the lid. If you see even the slightest shift, it means that the TDC is set incorrectly and the shafts require adjustment.
โ ๏ธ Attention: It is strictly forbidden to turn the crankshaft counterclockwise. This can lead to slipping of the oil pump drive chain (if there is one) or disruption of the belt tension, which will ruin the installation geometry.
There are cutouts on the camshaft gears that should look straight up and coincide with the plane of the cover. The mark on the crankshaft gear should be directed straight up. Only in this position can the clamps be installed.
Installing clamps and checking tension
The most crucial moment is installation camshaft clamp. The bar should fit freely into the grooves at the ends of the shafts without the use of force. If you have to apply force, it means the shafts are misaligned and you need to turn the crankshaft again. Improper fixation can damage the camshaft lobes or break the retainer itself.
After installing the bar, you need to check the crankshaft fixation. A locking pin is inserted into the hole on the clutch housing and should fit freely into the flywheel. If the pin doesn't go in, it means you haven't hit TDC and you need to adjust the crankshaft position.
โ๏ธ Checking the installation of fasteners
- ๐ The camshaft retainer must fit snugly against the ends of the shafts.
- ๐ฉ The crankshaft stopper should tightly block the rotation of the flywheel.
- โ๏ธ The timing belt should be tensioned according to the pulley indicator.
The tension pulley on these engines has a tension indicator. When the tension is correct, the mark on the roller should align with the cutout. If the mark does not match, you need to tighten the roller with a wrench, observing the direction indicated on the body. Excessive tension will kill the bearing, while too little tension will cause it to jump.
- ContiTech
- Gates
- INA
- Original Skoda
Belt installation diagram and tension features
When installing a new belt, it is important to follow the order in which it is placed on the gears. Start with the crankshaft gear, then pull the belt onto the pump, then onto the intake camshaft gear, and finally onto the exhaust camshaft. There should be no sagging in the area between the crankshaft and the pump.
It is important to ensure that the belt teeth fit tightly into the gear grooves. If the teeth do not match, there is no need to forcefully turn the shafts. Remove the belt, check the position of the marks again and start the procedure again. On engines 1.6 MPI There is no way to โpredictโ the tension without fixing the shafts.
After putting on the belt, you need to tighten it using a special pulley wrench. Turn the roller counterclockwise until the indicator is in the correct position. Then tighten the roller nut to the torque specified in the service book (usually 20 Nm + additional torque).
What happens if the belt installation order is mixed up?
If you put the belt on in the wrong order, you may not notice the phase shift by one tooth. The engine will run but will lose power, increase fuel consumption and may have trouble starting in cold weather.
After tensioning, be sure to rotate the crankshaft two full turns (720 degrees) clockwise. This action is necessary so that the belt falls into place and internal stress is relieved. Do not turn the engine counterclockwise at this stage.
Checking the crankshaft two revolutions after tensioning is the only way to ensure that the marks are not misaligned when installing a new belt.
Torque table and specifications
For correct engine assembly, it is important to observe the tightening torques of fasteners. Neglecting these parameters can lead to unscrewing of the pulleys or destruction of threaded connections. Below is a table with basic data for 1.6 MPI engines.
| element | Tightening torque (Nm) | Additional turn |
|---|---|---|
| Crankshaft pulley bolt | 110 | 90ยฐ (quarter turn) |
| Tensioner roller nut | 20 | Without additional rotation |
| Roller guide bolt | 20 | Without additional rotation |
| Timing cover fastening | 10 | Without additional rotation |
Pay attention to the crankshaft pulley bolt. This is a critical element that works for shearing when the engine starts. It must be replaced with a new one every time the timing belt is replaced. An old bolt may have stretched threads, which will cause it to come loose and end up in the oil pan.
It is also worth paying attention to the pump. On many engines Skoda Octavia 1.6 the pump is driven precisely by the timing belt. If it starts to make noise or leak, it must be replaced. Ignoring this detail can lead to the pump jamming and the belt breaking along the way.
Before installing the new pump, apply a thin layer of sealant to the seat, but do not use too much silicone so that it does not get into the internal passages of the engine.
Common mistakes and how to avoid them
The most common mistake is trying to set marks without using clamps. The master relies on the visual coincidence of the marks, but due to play in the bearings, the shafts can move by fractions of a millimeter. For 1.6 MPI engine this is critical since the clearance between the valves and pistons is minimal.
The second common problem is incorrect roller tension. If the tension indicator does not coincide with the mark, many try to โtightenโ the roller even more without tightening the crankshaft. This leads to the fact that after cranking the engine, the belt becomes overtightened or weakened.
โ ๏ธ Caution: Never use a hammer or pry bar to fit the belt onto the gears. This can damage the belt teeth, causing it to quickly wear out and break.
It is also worth remembering to replace the seals. If the crankshaft or camshafts show signs of oil leakage, the seals need to be replaced. Oil that gets on the timing belt destroys the rubber, and the belt begins to slip or break. For Octavia with a mileage of more than 100,000 km, replacing oil seals when replacing the timing belt is a smart investment in reliability.
Why can't I use the old crankshaft pulley bolt?
The crankshaft pulley bolt is a one-time use item. After the first tightening, its thread is deformed and it loses its elastic properties. If used repeatedly, it may become loose due to vibration, causing serious engine damage.
Completion of work and inspection
After installing all components, you need to check that the marks match again. Remove the clamps, turn the engine by hand two turns and make sure that the marks match again. If something is wrong, the procedure must be repeated again. Do not attempt to start the engine unless you are sure of the correct installation.
The first start of the engine after replacing the timing belt should be done in cranking mode with the starter without fuel supply (turning off the injectors) to ensure that there are no mechanical jams. Only after this can you connect the injectors and start the engine. The engine should run smoothly, without any extraneous noise.
- โ Check for oil leaks from the new timing cover gasket.
- โ Make sure the belt does not touch the guard when rotating.
- โ Listen to the operation of the tension roller - it should rotate silently.
If everything went well, assemble the attachment and test drive it. Closely monitor the engine temperature and the absence of errors on the instrument panel. The appearance of valve timing errors (P0016, P0017) immediately after replacement is a sign that the marks are set incorrectly.
โ ๏ธ Attention: If, after replacing the timing belt, the engine is unstable or the "Check Engine" light comes on, stop immediately and check the timing. Driving with the phases mixed up can cause the pistons to hit the valves.
FAQ: Frequently asked questions
Is it necessary to change the timing belt on 1.6 earlier than the regulations?
The scheduled service life is 210,000 km or 10 years, but experts recommend changing the kit every 90,000โ100,000 km. This is due to the fact that rubber loses elasticity over time, and operating conditions in our region are often more severe than those expected by the factory.
Is it possible to change only the belt without changing the roller and pump?
Technically possible, but highly undesirable. A new belt installed on a worn pulley can quickly break. A pump that has not been replaced may jam after 10,000 km, which will lead to a broken belt and expensive engine repairs.
How often should tags be checked after replacement?
The first check should be carried out 500โ1000 km after replacement. If the belt is installed correctly and there are no extraneous noises, additional checking of the marks is not required, unless symptoms of engine problems arise.
What 1.6 engine codes are found on Octavia?
On Skoda Octavia There are engines with codes BGU, BSE, BSF, CCSA, CFNA, CWVA. The method for installing marks for all these motors is almost identical, since they belong to the same EA111 series.