Engine knock on cold in Polo Sedan

In the modification of the Polo Sedan, owners often experience a cold blow from the engine.

Causes of engine knocking Polo sedan

A properly adjusted engine in good condition with sufficient oil runs smoothly and without interruption. Experienced drivers refer to this condition as "whispering". Knocks are manifested in the form of episodic, short, non-standard sounds that regularly violate the overall picture. By the nature of the impact, its echoes and location, the wipers even determine the cause of the malfunction.

The VW Polo sedan is different in that in this model, users often encounter such a nuisance as engine knocks when cold. When starting the engine after stopping, short-term crackling or rattling is observed.

After working for a certain period of time (usually from twenty to thirty seconds to one and a half to two minutes), the bump decreases or completely disappears.

Among the main causes of knocking in a cold engine are the following:

1. Incorrect operation of hydraulic lifters. Although each node has its own resource, even relatively new hydraulic lifters may not work normally. The reason often lies in low-quality oil, which disrupts the work. When disassembling a VW Polo engine, sometimes it is enough to replace the “dead” hydraulic lifters, although often the cause must be looked for further.
2. Another problem is the wear of the crankshaft main bearings. In the cooled state, the metal parts of the friction pairs have the smallest dimensions, gaps appear between them. After the engine warms up, the parts expand and the gaps disappear, the knock stops. This is the normal state of the engine, which has already traveled many thousands of kilometers, sooner or later, a scheduled replacement of the necessary parts will still be required.
3. Knocking in the clockwork. When it's cold, large gaps appear in the beds of the camshafts. Also, the call can be supplemented with a not entirely successful chain.
4. The most dangerous reason is the wear of the pistons along with the rings. If there is friction on the piston or cylinder, over time this can cause the engine to seize. Often it’s easier to just practice, so according to the laws of physics, they hang a little on a cold engine, but due to thermal expansion, they fall into place when wear is not so critical. If the owner of the car heard that the knock is progressing and does not go away when warmed up, this is an indication for urgent disassembly of the engine.

Engine features Polo sedan

The community of car owners noted that hitting a cold engine often has little to do with mileage. It is logical to hear extraneous sounds in an engine that has traveled about 100 thousand kilometers, but often a knock is observed at 15 thousand and even earlier. As a result of the discussion, it was concluded that knocking is generally characteristic of the CFNA 1.6 engine, which is equipped with cars sold in Russia and some other countries. Despite the German assembly, it has features that create conditions for strange nuances of engine operation even with low mileage:

1. Tight exhaust manifold. Due to the specific design, exhaust gases are poorly removed after combustion. Some cylinders (in operation) result in uneven wear resulting in cold detonation.
2. The special shape of the cylinders and their coating means that there is a click when passing top dead center. As it wears off, it becomes more intense and audible, becoming the same rhythm. For a long time it can be quite safe, but then the lottery begins - someone is lucky and he will drive further, while someone will have scratches on the cylinder walls.

Pillow knock

Sometimes the cause may not be in the engine itself, but in the way it is installed in the car. When engine mounts wear or shrink, metal can vibrate against metal. Also check these places carefully if you are buying a used car.

A worn-out pillow is often covered with several overlays, which, having loosened a little, can start rattling in the cold.

Knock prop

Unfortunately, no one canceled the fatigue of the metal. The engine cushion, experiencing constant loads, can violate its integrity, microcracks appear on it. Its invisibility during external examination causes bewilderment among many owners.

Read also How to change the brake pads on a Volkswagen Polo Sedan

What can be done

Some car enthusiasts have been driving the Polo sedan for years with cold weather. The engine itself is quite reliable and well assembled. However, if you hear a disturbing sound, it's best to take the car to an authorized service or dealer for further troubleshooting. As measures after disassembly, you can take the following:

• replacement of hydraulic lifters;
• time settings;
• replacement of crankshaft bushings;
• replacing the piston group and exhaust manifold.

Summary

On specialized forums, you can find information that even after repair, the knock returns after a dozen or two thousand kilometers. We have to admit that CFNA engine knock is typical and in many cases practically harmless. However, such a conclusion can only be given after a complete diagnosis of the car.