Whistling on a cold engine
Content
Whistle on the cold can be caused by the following reasons - slippage of the drive belt of mounted units, a decrease in the amount of lubricant in individual bearings or rollers of the power unit elements. However, there are more rare cases, for example, dirt getting into the streams of the generator pulley. Often, to eliminate the whistle on a cold internal combustion engine, it is enough to perform some manipulations, rather than buying a new belt or roller.
Why is a whistle heard on a cold
Exist four main reasons, due to which a whistle appears during a cold start. Consider them in order from the most common to "exotic".
Alternator belt problem
The most common reason that a whistle is heard when starting an internal combustion engine on a cold one lies in the fact that the alternator belt slips in the internal combustion engine of a car. In turn, this can be caused by one of the following reasons:
- Weak belt tension. Typically, the alternator belt does not have teeth, such as a timing belt, so its synchronous operation with a pulley is ensured only by sufficient tension. When the corresponding force is weakened, a situation arises when the generator pulley rotates at a certain angular velocity, but the belt on it slips and “does not keep up” with it. This creates friction between the inner surface of the belt and the outer surface of the pulley, which often results in whistling sounds. Please note that with a weak tension, a whistle can occur not only when starting the internal combustion engine, but also with a sharp increase in engine speed, that is, during gas flow. If so, check the belt tension.
- Belt wear. Like any other part of the car, the alternator belt gradually wears out over time, namely, its rubber becomes dull, and accordingly, the belt itself loses its elasticity. This naturally leads to the fact that, even with the proper tension, it cannot “hook” on the pulley to transmit torque. This is especially true at low temperatures, when the already dried rubber also becomes frozen. Accordingly, when starting the internal combustion engine on a cold, a short whistle is heard, which disappears as the engine and the alternator belt warm up.
- The appearance of dirt in the streams of the alternator pulley. Often, a whistle under the hood on a cold one appears not for a reason related specifically to the belt, but due to the fact that dirt accumulates in the pulley streams over time. This causes the belt to slip along its working surface, and is accompanied by whistling sounds.
How to eliminate the whistling of the alternator belt
Why does the alternator belt whistle and how to deal with it. 5 basic reasons for the whistling of the attachment belt (alternator belt, power steering belt, pump, air conditioning compressor). Causes of belt whistling and tips for eliminating it. More details
Similar reasoning is valid for other belts used in the car. namely, the air conditioning belt and the power steering belt. If left idle for a long time at a cold temperature, they can suffocate and make whistling sounds until they warm up as a result of their work. Similarly, they can whistle due to a weak tension and / or due to their strong wear.
In rare cases, in cold weather, the grease in the generator shaft bearing can thicken significantly. In this case, belt slippage is possible immediately after starting, since the internal combustion engine needs to exert more force to spin the generator shaft. Usually, after the lubricant acquires a more liquid consistency, belt slippage, and, accordingly, whistling sounds, disappear.
also, in rare cases, the belt may whistle and slip due to the fact that moisture condenses on its inner surface (adjacent to the drive pulleys). For example, when a car is parked for a long time in conditions of very high humidity (at a car wash, in a hot sea climate). In this case, after starting the internal combustion engine, moisture will naturally evaporate and the whistle will disappear.
Like moisture, various process fluids can get on the belt. For example, oil, antifreeze, brake fluid. In this case, the duration of the whistle will depend on how much liquid has got on the belt, and how quickly it will be removed from its surface. In this case, in addition to assessing the condition of the belt and its tension, it is imperative to diagnose why this or that process fluid gets on the belt. And make appropriate repairs. They will depend on the cause.
Worn idler roller
In machines equipped with a tension roller, it is he who can become the source of the “cold” whistle. namely, the roller bearing, which gradually fails. it can also whistle or crackle at certain engine speeds. Roller diagnostics must begin with checking the tension. Often, the roller begins to whistle when the drive belt or timing belt is under- or, conversely, over-tensioned. Please note that over-tightening the belt is harmful to the bearings of the individual rollers and pulleys that the specified belt connects.
you also need to assess its general condition. To do this, you need to dismantle the roller from its seat. next you need to inspect its wear and ease of rotation of the bearing. Be sure to check the roller (bearing) for play, and in different planes. Along with the diagnosis of the roller, you need to check the condition of the belts.
Water pump failure
The pump, or another name for the water pump, can also make a whistle when the engine is cold. On some older vehicles, the pump is driven by an additional belt from the crankshaft pulley. In modern cars, it is spinning with a timing belt. Therefore, often on older cars, the pump drive belt can also stretch and slip over time. An additional source of unpleasant sounds can be a worn pump pulley. The belt will slip over it and whistle.
Often, when the belt heats up, the whistle disappears, because if the belt is not very stretched, then it stops slipping and, accordingly, the whistling sounds will go away as the power unit warms up.
Similarly, as with the generator, the bearing grease can thicken at the water pump, or even completely wash out with antifreeze from its working cavity. In this case, there will be a slight whistle when starting the internal combustion engine on a cold one. However, if there is no lubrication at all, then often whistling sounds will be heard not only in the cold, but also while the car is moving along the road.
In addition to such obvious and explainable reasons for a whistle under the hood on a cold one, there may also be completely unrelated to the operation of the belt and rotating mechanisms. So, for example, when warming up the internal combustion engine on VAZ cars (namely, the Lada Granta), there may be such a rare case as the resonance of the crankshaft position sensor. So, the sensor (abbreviated as DPKV) emits a high-frequency squeaking sound between its internal parts, as well as the engine body. This is due to the design of the sensor.
How to eliminate whistle when starting an internal combustion engine
Elimination methods will depend on the very cause of the whistle when starting on a cold internal combustion engine. So you may need:
- Tighten the belt.
- Clean the streams in the crankshaft pulley or generator.
- Replace the failed part, which may be a pump, roller, bearing.
- replace the harness.
Since, according to statistics, the alternator belt is most often “guilty”, the diagnosis must be started with it. It is recommended to perform an appropriate check every 15 ... 20 thousand kilometers or more often. Typically, a V-belt is used for the generator. When checking, you need to pay attention to the presence of cracks on its inner surface (streams) when the belt is bent. If there are cracks, the belt needs to be changed. The approximate recommended car mileage for replacing the alternator belt is about 40 ... 50 thousand kilometers. Please note that the life of a particular belt is also affected by its tension.
In the event that the belt tension has loosened, it must be tightened. This is usually done using an appropriate roller or an adjusting bolt (depending on the design of a particular vehicle and its internal combustion engine). If the tensioning mechanism is not provided, then in this case it is necessary to replace the stretched belt with a new one.
in order to determine what the belt or roller is whistling, since the sounds they make are very similar to each other, you can use special protective aerosols - rubber softeners. Most often, belt conditioners are used for this, less often silicone grease or the popular universal remedy WD-40. namely, it is necessary to spray said aerosol onto the outer surface of the belt. If it is worn, stretched and / or very dry, then such a temporary measure will allow for a while to eliminate the whistle.
Accordingly, if the remedy helped, it means that the worn belt is the “culprit” of unpleasant sounds. In the event that the indicated measure did not help, then most likely the roller is to blame, namely, its drive bearing. Accordingly, additional verification is required.
Some drivers, instead of replacing the indicated belts (both the air conditioner and the generator), use special tools - rubber softeners or friction enhancers (there is rosin in the composition). However, as practice shows, such tools can only be used as a temporary solution to the problem. If the belt has a significant mileage, then it is better to replace it with a new one.
When checking the belt, pay attention to the grooves of the pulleys. Do not be too lazy to remove the belt and walk along the HF pulley and generator with a metal brush, as well as brake cleaner in order to wash off all the dirt.
If it turned out that it was not the belt that was whistling, but the roller, then it was worth changing it. When the squeak comes from the bearings of the pump or the overrunning clutch of the generator, the part is also under replacement.
But if the squeak is emitted by a resonant DPKV, as happens on Frets, then it is enough to put a small gasket under it in accordance with the size of the sensor. So, cutting out a small foil gasket, install it between it and the internal combustion engine housing. Depending on the size of the gap, the gasket will have three to four layers of foil. the basic task of the gasket is to provide mechanical force on the sensor from top to bottom.
When performing similar work on other vehicles, the size of the gasket and its installation location may differ. To find out exactly where the gasket should be installed, you need to mechanically press the crankshaft position sensor housing with your thumb. That is, you can press both from top to bottom, and from bottom to top, or sideways. So empirically, you can find a position in which the sound will completely disappear or become much quieter.
