Semi Truck Transmission Issues? 5 Possible Reasons Why You’re Experiencing Them


Has your rig been giving you trouble when shifting gears lately? Hard shifts, slips, delays, and transmission-related warning lights are never something you want to ignore. You need to determine the problem and make the necessary repairs quickly. The following are five of the most common reasons you may be experiencing problems with your semi’s transmission.  

Your Tranny is Overheating

If your transmission is exposed to excessive heat, you will have problems. The internal components will wear and slip. Check your transmission temperature gauge regularly and stop to let things cool off if needed. Installing an auxiliary transmission cooler can help as well.

The torque converter may be failing in your transmission. When it does, it slips and produces excessive heat. Have the vehicle checked immediately when you notice a change in the way it operates. Doing so could save you lots of money.

You Have Low Transmission Fluid

Not having enough transmission fluid is a common cause of shifting problems in semis. The fluid keeps things lubricated and provides hydraulic pressure for gear changes. You may experience delayed or hard shifting or complete transmission failure if levels get too low. Routinely check your dipstick and top off the fluid as needed. Any leaks should also be addressed immediately to prevent low fluid.  Learn how a semi truck service here can help resolve this problem.

Your Filter/Fluid is Dirty  

Over time, contamination builds up in the transmission through component wear and blow-by. A clogged transmission filter prevents the proper flow of fluid and fails to trap further contaminants. This starves the transmission of fresh fluid and allows even more metal particles and debris to circulate within it.  Dirty fluid and filters lead to reduced hydraulic system pressure, stuck valves, slipping, and rough shifts. To avoid this, closely follow OEM service intervals for fluid and filter changes.  The small upfront cost pales in comparison to the alternative.

You Have Worn Components

The constant demanding operation of a big rig leads to a lot of wear on internal transmission parts like bands, clutches, bearings, and gears. Excessive wear causes loose tolerances, leaks, low pressure, and damage. Have any leaks, slipping, or abnormal vibrations inspected immediately. Rebuilding or replacing worn parts reduces breakdowns, and proper operation and maintenance prolong component life. However, some worn parts like bands, clutches, and gears may still need rebuilding or replacing to restore proper mechanical operation. Watching for signs of abnormal wear and addressing them quickly reduces the need for more extensive repairs later on.

There’s Electrical System Damage

Truck transmissions rely on electrical solenoids and speed sensors to facilitate smooth shifts. Problems with wiring harnesses, connectors, sensors, or solenoids can all affect shifting performance. Electrical issues may be tricky to diagnose yourself. At the first sign of shifting delays or problems, have the codes read and the entire electrical system inspected by a professional. Catching problems early on reduces bigger repair bills down the road.

Don’t Ignore Warning Signs

Identifying and addressing transmission problems quickly can mean the difference between a minor repair and a complete breakdown. Pay attention to how your rig is shifting and watch for leaks, odd noises, warning lights, or abnormal smells coming from the transmission. Investigating warning signs early allows you to get back on the road faster and avoids creating even bigger issues through neglect. With proper preventative maintenance and care, the transmission in your semi will log many more reliable miles.

Leave A Reply