A reader had an interesting question this week. He was looking to buy a “new” a car, so he went to We Sell Cars and found a good condition vehicle with a CVT gearbox. Having always driven manual vehicles, he found the drive somewhat disconcerting. There was a slight delay when he stepped on the accelerator before the car accelerated. Also, he could not tell the speed of the car by the ‘feel’ of the engine. He asked if this is “normal” for a CVT, or perhaps this CVT was damaged? How would he know?

For those unfamiliar with the acronym “CVT”, it stands for continuously variable transmission. A CVT transmission uses a pair of variable-diameter pulleys and a belt or chain to provide unlimited gear ratios.

Most of us understand how traditional manual and automatic gearboxes work. A manual has a set number of gears, and the driver determines which gear ratio they need. An automatic also has a set number of gears, but it utilises a hydraulic system that responds to pressure created by the conditions to determine the gear needed without any input from the driver.

A CVT is like an automatic in that it does not use any input from the driver, but that is where the similarities end. A CVT does not have any gears. The most common CVT architecture has two pulleys. One pulley connects to the engine, and the other connects to the wheels. A flexible belt connects the two pulleys

The diameter of the pulley’s changes depending on how much power the vehicle needs. When one pulley gets larger, the other one gets smaller. Since neither the pulleys nor the belt is fixed, they can provide an infinite number of gear ratios, unlike the automatic, which has a set number of gears.

Symptoms of a bad CVT Transmission

 In order to know what you might have to look out for in your car or keep it long lasting and working properly, you need to keep an eye and ear out for potential CVT transmission problems and the symptoms of a bad CVT transmission. 

1. Unusual Noises - There may be noise coming from the CVT transmission. The gears of the transmission slowly wear themselves down over time, causing strange noises to occur when shifting gears or moving out of the idle position. If you hear any loud sounds, like clanging, banging, or screeching, these could be clear symptoms of a bad CVT Transmission. The solution ranges in price and severity, going from replacing transmission fluid to replacing the transmission completely. 

2. Burning Smell - if you notice a burning smell in your car, then the smell of burning something can be evidence of an overheating CVT Transmission and can be a symptom of a bad CVT Transmission.

3. Leakage - any leakage in your car could be a symptom of a bad CVT transmission. The bad smell can also point to a kind of leakage in your car, whether it is oil or transmission fluid.

4. Slipping Gears - a very common symptom of a bad CVT transmission is that the transmission is slipping gears. This is a common problem that is a result of structural problems or not enough transmission fluid, which causes the potential of gears to pop out of gear while you are driving. 

5. Delayed Movement - a key symptom of a bad CVT transmission are delays in movement. If your vehicle stalls for a second or two before shifting gears smoothly, this should be a cause for concern and can be the direct result of any issue. Car owners experience this issue common for a variety of reasons, serving as evidence for gearbox malfunction or transmission fluid issues. 

6. Surging, Lurching or Jumping - Along with the other common symptoms of a bad CVT transmission, surging can be a sign of contaminated transmission fluid. When your transmission becomes too polluted or filled with debris over time, your vehicle might begin to accelerate, jerk, lurch. Jump forward or fall back for no apparent reason. Sometimes, a transmission fluid flush could be all you need to solve the problem.

7. Reversing - Also, a refusal to reverse is a symptom of bad CVT transmission, with cold weather making the problem to reverse much more prevalent, and making it a key and obvious sign that your transmission is in trouble and you have a bad transmission.

8. Muddy Fluid - Muddy fluid or debris filled fluid could be a symptom of bad CVT transmission. If it has a slightly sweet smell and is bright red in colour, then that is working correctly. If the fluid in the transmission starts to look murky, do what you can to get it changed immediately.

9. Engine Light On- if the all-encompassing engine light is on, this, in addition to experiencing some or all the symptoms above, can be a sign that the CVT is giving trouble.

10. Trouble Starting – Again, in isolation, trouble starting could be due to numerous reasons. If your vehicle will not start or will take several attempts to start, becoming more frequent in the cold, AND you are experiencing other symptoms such as surging or slipping, then it could be your CVT.

How to ‘test drive’ a car with a CVT 

Despite all the charms of the vehicle you wish to buy, notably the excellent fuel economy, CVT’s come with a cost that must be closely considered. The main disadvantage of the CVT Transmission is the price tag they come with. A typical CVT replacement can often cost between R40 000 and R80 000 when they fail. Notice how I said when they fail? The CVT unit will not last nearly if the typical automatic transmission. In fact, most of these units last around 150 000 kilometres or less.

Even more important to note is the fact that when they fail, 9 times out of 10 they must be replaced. The reason for this is because parts are very expensive, can be difficult if not impossible to locate, and generally see so much damage they are not even worth attempting to rebuild. Another disadvantage of the CVT is the fact they cannot withstand the horsepower that an automatic or manual transmission can hold up to. For this reason, the CVT unit is not used in any high-performance situations.

That said, if you still wish to purchase a used CVT, look out for the following symptoms when test driving the car:

1. Look out for slow shifting. While you don ‘t has to shift a CVT transmission from first to second gear, you do have to shift between park, drive, and reverse to use your car correctly. If it takes more than just a second or so for the transmission to shift, it can show a faulty CVT Transmission

2. Listen out for strange sounds coming from your transmission. CVT transmissions are usually louder and make more sounds than their traditional manual or automatic counterparts, but they should not be too loud that humming and whining sounds are normal and commonplace for drivers. If you hear too much noise or excessive sounds when accelerating your car, or jerking while accelerating, these are symptoms of a bad CVT Transmission. 

3. Be aware of the transmission is slipping. When you accelerate your vehicle, you should experience a smooth, seamless, and constant acceleration for your car. If the transmission or acceleration slips and you lose power during driving, is a symptom of a bad or faulty CVT transmission. 

4. Jerking while shifting or uneven shifting during acceleration could occur when you are shifting or accelerating in your car. Shifting should never jerk the vehicle, so if it is, these are symptoms of a bad CVT transmission. 

5. Inconsistent RPM are symptoms of a bad CVT transmission. A CVT transmission should remain consistent and smooth, so if there is a fluctuation and discrepancy in the engine RPM while you are driving at a consistent speed, this is a sign there is a problem with your car.