FLUID LEVEL & LEAKS

(from www.aa1car.com)

One of the most common complaints with automatics is fluid leaks. Fluid can leak out of the driveshaft seals, the input shaft seal, the transmission pan gasket, the torque converter or the ATF cooler and line connections. If the fluid level gets low, the transmission may be slow to engage when it is shifted into drive. Gear shifts may be sloppy or delayed, or the transmission may slip between shifts. If the fluid level is really low, the transmission may cause the vehicle to not go at all.

On most vehicles, the fluid level should be checked when the fluid is hot with the engine idling, the parking brake set and the transmission in Park. If fluid is needed, add only enough ATF to bring the level up to the full mark. Do not overfill because doing so can cause the fluid to become aerated, which may affect transmission operation.

If the dipstick reads low, the transmission is probably leaking. So look underneath to see where the fluid is going. If there are no visible leaks, check the radiator for ATF in the coolant. The ATF cooler inside the radiator may be leaking and cross-contaminating the fluids.

You should also check the condition of the fluid. Some discoloration and darkening is normal as the fluid ages, but if the ATF is brown or has a burnt smell, it is badly oxidized and needs to be changed. Varnish on the dipstick is another indication of worn out fluid.

You can also do a "blotter test" to check for worn fluid. Place a few drops of ATF on a paper towel and wait 30 seconds. If the spot is widely dispersed and red or light brown in color, the fluid is in satisfactory condition. But if the spot does not spread out and is dark in color, the ATF is oxidized and should be changed.

Many transmission experts say most transmission problems can be prevented by changing the ATF and filter regularly for preventive maintenance. How often depends on how the vehicle is driven. For some vehicles, this might be every 30,000 miles or two years.

The harder the transmission works, the hotter the fluid runs. The life of the fluid drops quickly once its temperature gets up above about 200 degres F. Installing an aftermarket auxiliary ATF cooler that is parallel to the OEM ATF cooler is recommended to keep fluid temperatures down on vehicles that are used for towing or are driven hard.

ATF also becomes contaminated with normal wear particles from the clutch plates, bushings and gears. The filter will trap most of this debris before it can cause problems. But many older Asian transmissions only have a plastic or metal screen that does little to protect the transmission against internal contaminants and nothing to keep the fluid clean. On these vehicles, changing the fluid is the only way to get rid of these contaminants.

When adding or replacing ATF, use the type specified by the vehicle manufacturer. GM, Ford, Chrysler, Honda, Mercedes and others all have their own specs for ATF. There is no such thing as a "universal" ATF that works in all transmissions. Some fluids meet a variety of specifications, but cannot meet them all because of the different friction additives that are required.

Ford has three automatic transmission fluid specifications: Type F (a non-friction modified formula for most 1964-81 transmissions), Mercon (a friction modified ATF similar to Dexron II for 1988-97 transmissions), and Mercon V (Fords latest friction-modified formula, introduced in 1997).

General Motors has two specifications: Dexron II and III. Both are friction modified formulas and Dexron III can be used in the older GM transmissions that originally required Dexron II.

Chrysler has a number of different ATFs: MS-7176D (also known as ATF+2) is Chryslers version of a friction-modified ATF that is similar to Dexron II. But Chryslers fluid is more slippery than GMs, so Chrysler recommends using only ATF that meets their specs in Chrysler transmissions. In other words, do not use Dexron or Mercon in a Chrysler transmission.

Chrysler MS-7176E (also known as ATF+3) was introduced in 1998 and supersedes ATF+2. It should only be used in 1998 and newer Chrysler transmissions, but can also be used in earlier Chrysler transmissions.

Chrysler ATF+4 is for 2000-01 model year applications, and their newest fluid ATF+5 is for 2002 and newer models.

Visit Trevino Transmissions (www.trevinotrans.com) for Transmission Repair in El Paso Texas.