Many automotive noises creep up on you. The first time you notice it you may wonder if you’re hearing anything unusual at all. Then you start to wonder how long this has been going on before you noticed. Automotive noises can stress you out. The car seems to be working fine, but you know something must be going wrong. How serious is it? Is the car unsafe, or is it going to let you down somewhere?
Interpreting automotive noises is often a matter of experience so the amateur mechanic is usually at a disadvantage because their experience is usually limited to the cars that they or their family own. But there are a few symptoms that are common across a range of cars and a few logical checks can help you figure out what is going on.
Part 1 of 1: Troubleshooting a whining sound
- Mechanic's stethoscope
- Workshop manual
Step 1: Ruling out engine noise. If the car doesn’t make the noise when it is not in gear, chances are it isn’t an engine noise.
Race the engine gently with the car in Neutral and listen carefully for any signs of the offensive noise that are associated with the engine speed. With a few exceptions, a noise that occurs when the car is shifted into gear is most likely associated with the transmission.
Step 2: Manual or automatic. If your car has a manual transmission, the sounds that it makes can mean entirely different things from an automatic.
Does the sound occur when you put your foot on the clutch to shift into gear? Then you probably looking at a release bearing, which means clutch replacement. Does the sound occur as the car just starts to move as you release the clutch then go away when the car is in motion? That would be a pilot bearing, which also means clutch replacement.
A manual transmission is only turning when the car is either in motion, or when the transmission is in Neutral and the clutch is engaged (your foot is off the pedal). So sounds that occur while the car is stationary and in gear are most likely associated with the clutch. Whirring sounds that occur while the car is in motion may indicate transmission bearing noises or driveline noises.
Step 3: Check the fluid. If your car has a manual transmission, checking the fluid can be a big job. The car has to be jacked up and a check plug removed from the side of the transmission.
An automatic transmission might be easier, but in recent years manufacturers have started to eliminate dipsticks and fill spouts from the user serviceable hardware. Check your workshop manual for instructions on checking the automatic transmission fluid.
Either way, it’s an important step. Low fluid can cause all sorts of problems, and noises are usually the first noticeable symptoms. Catching a low fluid level early can save you a lot of money.
If the noise began shortly after you had the transmission serviced, contact the service professional to find out exactly what kind of fluid was used. In the last 15 years, many transmission manufacturers have each been using their own special fluid, and using anything else can sometimes cause inappropriate noises.
Step 4: Put the car in Reverse. If your car has an automatic transmission, there are a few other checks you can make.
With the engine running, put your foot on the brake and put the car in Reverse. Does the noise get worse? If this is the case, you might have a restricted transmission filter.
When the car is is in reverse, the transmission pressure rises and the transmissions demand for fluid rises with it. A restricted filter will not allow the fluid to pass quickly enough. You can change the fluid and filter if this is the case or have it done for you but it might not be the end of your troubles. If the filter is clogged, it is clogged with debris from the inside of the transmission, so something else is breaking down.
Step 5: Check the torque converter. The torque converter is what your automatic transmission has instead of a clutch. The torque converter is spinning anytime the engine is running, but is only under load when the car is in gear either forward or reverse. As soon as you shift into Neutral, the sound goes away.
The torque converter is located where the engine meets the transmission. Put your mechanic’s stethoscope in your ears, but pull the probe off of the hose. This will give you a very directional tool for seeking out sounds.
While a friend keeps the car in gear with their foot firmly on the brake, wave the end of the hose around the transmission and try to pinpoint the direction the noise is coming from. A torque converter will generate noise from the front of the transmission.
Step 6: Drive the car. If the noise doesn’t occur unless the car is in motion, you may have trouble with one or more gears or bearings in the transmission. There are many parts in the transmission that are stationary unless the car is under way. Planetary gear sets can produce whining noises as the gears begin to wear out but they will only complain when the car is moving.
Determining and correcting the exact cause of transmission noise may be beyond the scope of the amateur mechanic. If the problem cannot be solved by topping off the oil, or changing the filter, there is probably little that can be done that doesn’t involve transmission removal. Having it checked by a professional at home by a technician, such as one from YourMechanic, can go far towards easing your worry.
This article originally appeared on YourMechanic.com as How To Troubleshoot a Car That Makes a Whining Noise When In Gear and was authored by John Hege.