NEW FLUID LEVEL INDICATORS AND NEW FLUID CHECK PROCEDURES

SUBJECT: New Fluid Level Indicators and Fluid Check Procedures

VEHICLE APPLICATIONS: B, D, F, Y - Cars C/K, R/V, S/T, P - Trucks G, M/L - Vans

TRANSMISSION APPLICATIONS: 1991-92 HYDRA-MATIC 4L60 (MD8) 1991-92 HYDRA-MATIC 4L80-E (MT1)

TRANSAXLE MODELS: All

New Fluid Level Indicators:

During the 1991 and 1992 Model Years, changes were made to the fluid level indicators (dipsticks) in most HYDRA-MATIC 4L60 and all HYDRA-MATIC 4L80-E transmissions.

The new fluid level indicators (all except 91 S/T trucks, G and M/L vans with 4L60) have a cold fill area that is located lower on the stick than the previous fluid level indicators. The area was moved in response to a fluid level study which showed the previous markings did not reflect current hot fluid expansion rates.

The cold area on the fluid level indicator may have two holes (dimples) to identify it, or it may have a section stamped "COLD". See figure 1 to identify indicators which have dimples and indicators which say "COLD".

When dealer prep personnel check transmission fluid levels in these vehicles, it is important to know the temperature of the transmission fluid before determining that fluid needs to be added. The dipstick "hot" and "cold" markings are calibrated to correspond to the following temperatures:

HOT 82-94 degrees C (180-200 degrees F) COLD 24-29 degrees C (75-85degrees F)

This means that if the fluid level is in the "COLD" range area while the fluid temperature is 24-29 degrees C (75-85 degrees F), the fluid will always expand to be within the "HOT" range area when the fluid temperature is 82-94 degrees C (180-200 degrees F).

Fluid level may be checked and adjusted only if the fluid temperature falls within either the "HOT" or "COLD" range area.

Driving the vehicle a few miles will not expand the fluid into the hot (crosshatched) range. DO NOT ADD FLUID DURING A HOT CHECK UNLESS YOU CONFIRM FLUID TEMPERATURE IS 82-94 DEGREES C (180-200 DEGREES F), AND THE INDICATOR SHOWS THE FLUID IS BELOW THE CROSSHATCHED AREA.

DO NOT ADD FLUID DURING A COLD CHECK UNLESS YOU CONFIRM FLUID TEMPERATURE IS 24-29 DEGREES C (75-85 DEGREES F), AND THE INDICATOR SHOWS THE FLUID IS BELOW THE "COLD" AREA.

Since the cold area has been lowered on the fluid level indicator, if the transmission fluid is not warmed up enough, you will get a false low reading.

New Fluid Check Procedure:

NOTICE: Excess fluid or insufficient fluid can cause damage to the transmission. Be sure to get an accurate reading when you check the transmission fluid.

Wait at least 30 minutes before checking the transmission if the vehicle has been driven:

- When outside temperatures are above 32 degrees C (90 degrees F). - At high speed for quite a while. - In heavy traffic--especially in hot weather. - While pulling a trailer.

To check transmission fluid hot:

A hot check is made when the transmission temperature is 82-94 degrees C (180-200 degrees F). This can be accomplished by driving about 24 km (15 miles) when outside temperatures are above 10 degrees C (50 degrees F). If it's colder than 10 degrees C (50 degrees F), you may have to drive further.

To check transmission fluid cold:

A cold check is made when the transmission temperature is 24-29 degrees C (75-85 degrees F). You may have to let the engine run at idle to warm the fluid, or let the vehicle sit with engine off to cool the fluid. Let the engine run at idle for five minutes if outside-temperatures are above 10 degrees C (50 degrees F). If it's colder than 10 degrees C (50 degrees F), you may have to idle the engine longer.

Determining Fluid Temperature:

There are two ways to determine fluid temperature.

1. You may attach a thermocouple to the dipstick and directly read fluid temperature.

2. If the transmission is a HYDRA-MATIC 4L80-E, you can hook up a Tech 1 and read the transmission sump temperature.

To check the fluid hot or cold:

- Park the vehicle on a level place. - Place the shift level in "P" (Park) with the parking brake applied. - With your foot on the brake pedal, move the shift lever through each gear range, pausing for about three seconds in each range. Then, position the shift lever in "P" (Park). - Let the engine run at idle for 3-5 minutes.

Pull out the dipstick and wipe it with a clean rag or paper towel.

- Push it back in all the way, wait three seconds and then pull it back out again.

Check both sides of the dipstick and read the lower level. The fluid level must be in the cold area for a cold check or in to the hot (crosshatched) area for a hot check.

- If the fluid level is correct, push the dipstick in all the way. If the dipstick has a locking top, flip the handle down to lock the dipstick in place.

To Add Transmission Fluid:

If the fluid level is low, add only enough DEXRON IIE to raise the fluid level to the cold area for a cold check or the hot area for a hot check. DO NOT OVERFILL.

After adding fluid, recheck the fluid level.

When the correct fluid level is obtained, push the dipstick back in all the way. If the dipstick has a locking top, flip the handle down to lock the dipstick in place.

General Motors bulletins are intended for use by professional technicians, not a "do-it-yourselfer". They are written to inform those technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions and know-how to do a job properly and safely. If a condition is described, do not assume that the bulletin applies to your vehicle, or that your vehicle will have that condition. See a General Motors dealer servicing your brand of General Motors vehicle for information on whether your vehicle may benefit from the information.