Common Problems in 68RFE Transmissions and Effective Fixes

The 68RFE transmission, used in many Dodge Ram trucks since 2007, is a six-speed automatic transmission designed to handle the robust demands of diesel engines. Despite its widespread use, the 68RFE has been known to experience a range of common issues, particularly under heavy-duty usage. Understanding these problems and their effective fixes can help extend the life of your transmission and improve overall performance.

1. Low Line Pressure and Weak Clutch Packs

Problem:
One of the most common issues with the 68RFE is low line pressure, which can lead to weak engagement of the clutch packs. Over time, this causes the clutches to slip, resulting in premature wear and eventual transmission failure.

Symptoms:

Sluggish shifting between gears
Delayed engagement when shifting into Drive or Reverse
Overheating of the transmission

Fixes:

Upgraded Valve Body: Installing an upgraded valve body or a shift kit can help maintain proper line pressure, ensuring better clutch engagement.
Billet Input Clutch Drum: This modification increases the holding capacity and durability of the clutch packs.
Regular Maintenance: Periodically replacing the transmission fluid and filter helps maintain optimal line pressure.

2. Overheating

Problem:
Overheating is a major concern, especially for vehicles used for towing or heavy hauling. Prolonged high temperatures can degrade the transmission fluid and damage internal components.

Symptoms:

Transmission temperature warning light
Burning smell from the transmission
Reduced performance, particularly under load

Fixes:

Aftermarket Transmission Cooler: Adding a larger or auxiliary transmission cooler helps dissipate heat more efficiently.
High-Quality Transmission Fluid: Using synthetic fluids with higher thermal resistance can prevent fluid breakdown under extreme conditions.
Monitor Transmission Temperature: Installing a gauge to monitor transmission temperature allows you to take action before overheating causes damage.

3. Torque Converter Failure

Problem:
The torque converter in the 68RFE is prone to failure, often due to overheating or excessive wear. When the torque converter fails, it can lead to slipping, shuddering, or complete transmission failure.

Symptoms:

Shuddering or vibrations when accelerating
Poor fuel efficiency
Slipping in higher gears

Fixes:

Upgraded Torque Converter: Replacing the stock torque converter with a billet or high-performance version improves durability and efficiency.
Flush the Transmission: After a torque converter failure, it’s essential to flush the entire system to remove debris and prevent damage to new components.

4. Faulty Overdrive Clutch

Problem:
The overdrive clutch in the 68RFE can fail prematurely, especially in vehicles frequently operating in overdrive gear. This is often caused by insufficient lubrication and high stress on the clutch.

Symptoms:

Difficulty engaging overdrive gear
Noise or clunking when shifting to overdrive
Transmission slipping in higher gears

Fixes:

Overdrive Clutch Upgrade: Installing a performance overdrive clutch with improved materials can handle higher stress levels.
Adjust Shift Strategies: Avoid prolonged use of overdrive in heavy towing conditions. Use lower gears when hauling heavy loads.

5. Solenoid Pack Issues

Problem:
The 68RFE’s solenoid pack controls the flow of transmission fluid for shifting gears. When the solenoids malfunction, it can lead to erratic shifting or the transmission going into limp mode.

Symptoms:

Erratic or harsh shifting
Transmission stuck in one gear (limp mode)
Check Engine Light illuminated

Fixes:

Replace the Solenoid Pack: Faulty solenoids need to be replaced to restore proper fluid flow and shifting behavior.
Software Update: A reflash or update of the transmission control module (TCM) software can resolve some solenoid-related issues.

6. Pump Failure

Problem:
The transmission pump is responsible for circulating fluid throughout the system. Pump failure can result in inadequate lubrication and cooling, leading to catastrophic damage.

Symptoms:

Whining noise from the transmission
Low fluid pressure
Overheating or slipping

Fixes:

Install a Heavy-Duty Pump: Replacing the stock pump with a high-performance version ensures reliable fluid circulation.
Check Fluid Levels Regularly: Maintaining proper fluid levels prevents the pump from working under stress.

7. Weak Input Shaft

Problem:
The stock input shaft on the 68RFE may not withstand the high torque levels of modified engines or heavy-duty applications. A broken input shaft can leave you stranded with a non-functional transmission.

Symptoms:

Loss of power transfer
Grinding or snapping noise during operation

Fixes:

Billet Input Shaft: Upgrading to a billet input shaft significantly increases strength and torque capacity.
Avoid Excessive Power Loads: Use the transmission within its designed power limits to reduce strain on the input shaft.

8. Electrical Issues

Problem:
The 68RFE transmission relies heavily on electronic controls, making it susceptible to wiring and sensor failures.

Symptoms:

Erratic shifting
Intermittent Check Engine Light
Transmission stuck in limp mode

Fixes:

Inspect Wiring Harness: Look for damaged or corroded wires and repair them as necessary.
Replace Faulty Sensors: Diagnosing and replacing bad sensors, such as the input/output speed sensors, can resolve electrical issues.
TCM Replacement: In severe cases, the Transmission Control Module may need to be replaced or reprogrammed.

Preventive Maintenance Tips for 68RFE Transmissions

Regular Fluid Changes: Stick to the manufacturer’s recommended intervals for fluid and filter replacements to keep the transmission in top condition.
Use the Right Fluid: Always use high-quality fluids that meet the 68RFE’s specifications, such as ATF+4 or other compatible synthetic options.
Avoid Excessive Heat: When towing, use lower gears and ensure the transmission has adequate cooling.
Install Upgrades Proactively: If your vehicle is used in heavy-duty conditions, consider installing upgraded components before problems arise.
Monitor Performance: Pay attention to changes in shifting behavior or unusual noises, as they may indicate developing issues.

Conclusion

The 68RFE transmission is a reliable and capable system, but like any mechanical component, it has its vulnerabilities. By understanding common issues and implementing effective fixes, you can ensure your transmission operates smoothly and lasts longer. Regular maintenance, the use of high-quality fluids, and proactive upgrades are key to preventing major problems and keeping your vehicle performing at its best.