Common Signs of a Failing Heavy-Duty Truck Transmission

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Whether you are a truck driver, a fleet manager, or an operator of a delivery truck business, truck maintenance is a routine fact of your life. No matter how durable you think your trucks are, you can’t expect them to last forever. Delivery trucks and commercial vehicles are in a league of their own as they are often loaded with cargo, and they travel long distances. Even those who are religious enough about doing regular inspections and maintenance, at some point, will need to deal with some issues that warrant repair.  

During your truck’s lifetime, it is the transmission that takes a lot of use, wear, and beatings compared to other mechanical components. But since the transmission service and maintenance schedule and intervals vary according to the year, make, and model of the trucks and commercial vehicles, some drivers and operators fail to have the service done on time.

Minor issues with your truck’s transmission, if left unaddressed, can quickly worsen and become major problems. Transmission repairs can put a huge strain on your finances, and the longer your truck’s downtime is, the more money you are losing. So, it is worthwhile to pay attention to anything that feels or sounds unusual. At the first indication of a transmission problem, it pays to get your big rig checked by a pro, particularly one that specializes in working with semi-trailers, light to heavy trucks, and commercial vehicles.

But how do you know if your big rig’s troubles are related to the transmission system? Here are the common indications that your transmission is going bad:

• Leaking transmission fluid 

One of the easiest ways to spot a failing transmission is leaking fluid. This fluid is vital to your truck’s shifting capabilities as it lubricates the transmission’s moving parts. A small drop of the transmission fluid on your driveway can turn into a big problem. You can easily recognize if the fluid leaking out of the vehicle comes from the transmission as this is usually clear, bright red in appearance, and is a bit sweet-smelling when everything is working well. If the fluid has a burnt smell or has a dark, murky color, it is now time for you to pump it all out and replace it with fresh fluid. Also, if the transmission fluid is running low, there sure is a leak somewhere, and it must be checked by a pro.     

• Erratic shifting 

In a properly functioning automatic transmission, gear shifting should be done smoothly. If the gear shifts make the vehicle shake or if the transmission refuses to shift into the next gear, have your truck’s transmission checked the soonest.

Moreover, a sudden jump in your truck’s RPMs during gear shifts means there is a delay, and it could be a sign that the level of transmission fluid has dropped. Sometimes, a delay is accompanied by unusual noises. If such delay is felt while shifting gears, take your truck to a mechanic to have it inspected.  

• Unusual noises 

Other signs that your truck requires a transmission repair are unusual noises that occur when changing gears. These can be grinding, growling, or gurgling sounds that usually emerge because of low transmission fluid, incorrect ride height adjustment, or cracks in the gears.

• Gear slips

Slipping gears are not only symptoms of a failing transmission; but, these are also serious safety hazards for vehicle owners and nearby drivers and pedestrians. In such cases, the driver’s response to avoid a hazardous situation is to slam on the brakes or accelerate quickly. A big rig that fails to respond or slips into neutral or between gears poses a safety threat. If this is the case with your big rig, don’t think twice about taking it to a qualified transmission repair shop for proper inspection.  

In many modern transmissions, such an issue is prevented by providing the driver with an option to go to “safe mode” or “limp mode.” In these settings, the truck or vehicle’s computer system will sense any irregularity with the transmission and default to one gear. The transmission will operate in just one gear and avoid shifting between gears, enabling the driver to get to the nearest repair shop safely.

• Check Engine Light

In some cases, the check engine light can also be a great early sign that something is starting to go wrong with your rig’s transmission. When this light comes on, it doesn’t necessarily mean that your big rig will stop working soon. This indicator light illuminates for several reasons that may not be related to the transmission. This warning sign, however, should not be overlooked.

One of the easiest ways to know if the problem is with the truck’s transmission is using a diagnostic tool. There are circumstances when a diagnostic code points to a minor service that prevents major damage, which warrants costly repair, from happening. Sometimes, the diagnostic code informs the technician of a serious transmission issue that requires major repair.

• Acceleration issues

Smooth yet powerful acceleration can be achieved if your big rig is in proper working order. This system transmits the power from the engine to the wheels in order for your ride to accelerate. If you are experiencing slow or weak acceleration, it could be due to poor compression or a clog in the exhaust manifold or air filter.

If your mechanic recommends replacement of some transmission system components, FinditParts is here to help. This one-stop online truck parts and accessories shop carries a wide selection of top-quality transmission parts for your maintenance, rebuild, upgrade, and repair needs. We carry products from different brands and parts suppliers—from the world-renowned truck parts manufacturers to lesser-known brands specializing in transmission items.  

Do you need a highly durable differential, transmission gasket set, input shaft, snap ring, or transmission repair kit? FinditParts has got them all and more at pocket-friendly prices and reasonable shipping costs. Yes, we make sure to give you the best bang for the buck there is. Browse our online catalog now and allow us to help you address your truck’s transmission problem without breaking the bank.