Transmission Problems

Posted on

Problems with Automatic Transmissions


Automatic transmissions are the most commonly installed drive train option on modern vehicles.

Unfortunately, this convenient automatic shifting is sometimes accompanied with problems that can be expensive to repair.

In this section of the you fix cars website we will discuss them in general on this page, but at the bottom you’ll find detailed articles that talk about the theory of operation.

Maybe more important then how they work you’ll find posts about common transmission problems with specific models. Let me give you an example. My 2004 Chevrolet S10 Blazer truck came with the mighty 4L60E four speed transmission.

Unfortunately for my model year many of these automatic transmissions were fitted with a substandard sun shell supplied from China.

When the sun shell cracks you lose reverse. The reason I tell this story is that the 4L60E transmission is reliable on many model years.

On my particular year this is not the case. If you’re experiencing a problem with a specific unit you may want to do some checking to see if it is a repair trend or common problem.

Automatic Transmission Operation

This type of transmission does not need a clutch pedal and shifts through the forward gears without control from the driver all by itself when the drive range is selected.

Instead of a clutch and pressure plate to connect the engine to the rear wheels the automatic transmission uses a torque converter.

This is a fluid coupling to transfer the power from the engine’s flywheel to the transmission input shaft and then back to the wheels. The torque converter stall speed allows for proper engine idle without moving the vehicle and smooth transfer of power at all engine speeds.

On vehicles of the last 20 years the shifting is controlled by both electrical and hydraulic principles working together.

The hydraulic part of the equation is an intricate network of passageways, fluid controlled pistons and servos plus other components that use the magic of hydraulic oil pressure to control the internal operation.

The electrical part of the equation is usually the solenoids and electrically controlled valves that open and close to allow hydraulic fluid pressure to flow in the desired direction and accomplish a specific task.

On modern vehicles the main computer is what controls the operation of the electrical circuits. The computer uses its varied inputs from sensors such as vehicle speed and throttle position to determine what actions are necessary for the transmission to apply.

As an example, a solenoid valve can open to let hydraulic fluid flow to apply a certain gear set to perform a specific action. These gear sets provide many foreword speeds as well as reverse.

This system is extremely complicated and my auto shop instructor once told me that the inventor of this modern marvel wound up in a mental institution.

Even if you’re not going to repair it on your own it can be helpful to understand how it operates and the inherent problems that may occur on the exact model car or truck you drive to work everyday.

Car Repair

Posted on Updated on

Which cars cost least to repair?


The report, released Monday, shows which companies’ cars have both the fewest and the least expensive repairs. Hyundai, whose U.S. sales have surged this year, finished second in the rankings, published by auto diagnostic and repair website CarMD, which collects repair data from its network of 3,000 U.S. mechanics. Rounding out the top 5 were  Honda, Ford and General Motors — followed by Mitsubishi, Nissan, Kia, Volkswagen and Chrysler.

The report covers a wide range of model years, from 2001 to 2011, but focuses on repairs made only in the most recent year ending Oct. 1. While ranking individual car models, the CarMD Vehicle Health Index also grades manufacturers on a combination of all their brands. For example, the Toyota ranking includes Lexus and Scion cars, while General Motors includes Chevrolet, Buick, Cadillac and GMC.

Based on data from mechanics, the CarMD report differs from car-owner surveys, such as the Consumer Reports reliability survey. The CarMD index ranks individual car models as well as manufacturers, combining both frequency of repairs and repair cost for an overall rating.

The top-ranked model, the 2009 Toyota Corolla, had not only infrequent trips to the shop but an average repair cost of just $45.84. (Repairs picked up by this system cover everything with a check-engine light sensor, including engine, transmission and pollution control devices. Only items like belts and tires are not included.)

Car Repair Studies From CarMD:

  • Luxury brands generally fared worse because of repair frequency, not high costs. Lexus, for instance, rated more poorly than corporate stablemate Toyota. This conflicts with high owner ratings for Lexus in surveys like that from J.D. Power and Associates. The Mercedes-Benz parent company and BMW ranked below the top 10 in this report, though CarMD did not give ranking details beyond the top 10.
  • Hyundai has made great strides in low repair frequency. The company originally launched its 10-year, 100,000-mile warranty to reassure potential buyers. But Hyundai’s rating was boosted by strong performances from recent models of the Elantra and the 2011 Sonata, which ranked sixth among all models.
  • Ford got an especially strong performance from its Edge crossover SUV, which had three different model years ranked among the top 100 vehicles. But Ford’s Windstar minivan, discontinued in 2003 but still going to repair shops, hurt its ranking.
  • Among General Motors brands, Buick was a standout. If Buick had been ranked individually instead of wrapped into GM, it would have topped the list. Its Lucerne model had three different years in the top 100 cars.

As part of its Vehicle Health Index package, CarMD also cites which repair problems occur most frequently for individual car brands. If you want to check your car, go to this CarMD page and put in the make and year.

CarMD is a service aimed at letting car owners know what is wrong with their car and what it should cost to fix the problem. Its $119 CarMD device plugs into the diagnostic system on your car to discover the problem; users can then feed that data into their website to identify the problem and the likely repair cost, based on data the company collects regularly from mechanics at both dealer service departments and independent shops. Its database since 1996 includes about 500,000 repair reports.  Stop by for more info about automotive repair