Mechanic Tips

Addressing Transmission Slipping Issues: A Car Servicing Checklist

A slipping transmission can be one of the most frustrating issues for a car owner to experience. You press on the accelerator, yet the engine rpm climbs without the expected acceleration. This slipped gear effect is a common sign that your transmission needs attention. Ignoring it risks more serious and costly damage.

The good news is that, in many cases, transmission slipping can be resolved or prevented through proper maintenance and servicing. Let’s look at the likely causes of a slipping transmission and the maintenance steps you can take to get your car shifting smoothly again.

Common Causes of Transmission Slipping

Worn Clutch Disc or Pressure Plate: The clutch disc and pressure plate are responsible for engaging and disengaging the engine’s power to the transmission. If their friction surfaces become excessively worn or damaged, smooth power transfer will suffer. Replacing the clutch disc and resurfacing the flywheel will typically solve clutch slippage issues.

Low Transmission Fluid Level: Like any mechanical component, an automatic transmission needs sufficient fluid to operate properly. A low fluid level can cause delayed gear engagement, slipping, or hard shifts. Top up the transmission fluid to the proper level, inspect for any leaks, and test drive the vehicle.

Contaminated Transmission Fluid: Not only does the transmission need enough fluid, but that fluid should be clean. Contaminants like dirt, metal shavings, or clutch material particles will reduce the lubricating properties of the fluid. Drain, flush, and replace dirty transmission fluid to restore shifting performance.

Worn Transmission Bands or Clutches: The bands and clutches in an automatic transmission are critical for shifting gears. Excessive wear allows them to slip, leading to delays in power transfer through the driveline. Replacement of these internal parts may be necessary to restore positive gear engagement.

Electrical Issues: Modern transmissions rely on electrical solenoids, speed sensors, and electronic controls. Faulty wiring, connectors, or sensors can contribute to irregular shifting, including slipping. Diagnosing and repairing any transmission electrical faults is key.

Essential Transmission Maintenance Steps

Check the Transmission Fluid Level: 

This simple check takes just minutes but helps spot low fluid levels before they cause serious damage. Locate the transmission dipstick, typically near the engine oil dipstick. With the engine warmed up and running, pull out the dipstick, wipe clean, reinsert fully, then pull it out again to check the fluid level. It should fall within the indicated full or hot range. Top up as needed with the specified transmission fluid type.

Inspect the Condition of the Transmission Fluid: 

The fluid level is only part of the equation – quality matters too. Drain out a small sample to assess the condition. Transmission fluid should have a clear reddish color. Cloudiness, dark color, or a burnt smell points to contaminated fluid in need of replacement. Change the fluid at the specified service intervals or anytime you spot fluid degradation.

Check Transmission Fluid Leaks: 

Slow leaks can gradually drain transmission fluid levels causing slipping issues over time. Visually inspect around the transmission case, hoses, cooler lines, axle seals, and the dipstick tube for any evidence of fluid leaks. Trace any leaks back to their source and repair as necessary to prevent ongoing loss of fluid.

Replace a Worn or Slipping Transmission Filter: 

Transmission filters capture debris and prevent contamination of internal components. But clogged filters can impede fluid flow and circulation. Replacing a worn filter helps restore smooth operation and reduce strain on the transmission. Always use the correct filter for your specific transmission model.

Inspect and Replace Old Transmission Fluid Lines: 

Hard, cracked, or leaking transmission lines should be addressed to maintain fluid system integrity. Install genuine OEM replacement lines as needed to prevent collapse or further deterioration of old lines. This prevents fluid leaks and maintains proper line pressure.

Consider a Transmission Flush Service: 

Extremely contaminated fluid may require more than a drain and refill. A flush machine cycles fresh, clean fluid through the system multiple times to fully purge old fluid and debris from the inner passages. Transmission flushes can rejuvenate shifting performance, especially if the vehicle has no service history.

Address Any Transmission Electrical Issues: 

Faulty wiring and sensors often cause intermittent shifting problems. Check connectors for corrosion, damage, or loose pins. Inspect sensor mounting positions and output. Scan for any diagnostic trouble codes pointing to specific faults. Repairing identified electrical issues restores proper control signals to the transmission.

Regular transmission maintenance provides the essential fluids, operating pressures, filtration, and electronics needed for smooth, reliable shifting. But internal hard parts like bands, clutches, and gears are also subject to mechanical wear over time. If your transmission continues to slip after performing proper servicing, internal repairs or rebuild may be required by a transmission specialist.

Ignoring early signs of transmission trouble risks more extensive damage. But staying ahead of maintenance needs and addressing slipping issues promptly can often restore normal operation and extend the lifespan of your vehicle’s transmission.

What are the most common causes of a slipping transmission?

The most common causes are low fluid level, contaminated fluid, worn clutch components, worn transmission bands or clutches, and electrical problems like faulty speed sensors.

Does a slipping transmission mean I need a rebuild?

Not necessarily. Many slipping issues can be corrected through proper servicing and minor repairs. But a full rebuild may be required if internal hard parts are excessively worn.

What type of transmission fluid should I use for top-ups?

Always use the specific fluid type recommended by your vehicle manufacturer, found in your owner’s manual. Using the wrong fluid can damage your transmission.

How often should I change my transmission fluid?

For most vehicles, transmission fluid and filter changes are recommended every 30,000 to 60,000 miles. Refer to your owner’s manual for your specific model’s change intervals.

At SNC Automotive, our experienced mechanics can diagnose transmission issues and provide factory-recommended servicing to stop slipping and restore smooth shifting. As a leading auto repair in Brendale for over 20 years, we care for your car as our own. Contact us today to schedule an inspection.

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