Chevrolet Full-size Cars 1968-1978 Repair Guide

Automatic Transmission

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FLUID RECOMMENDATIONS & LEVEL CHECK





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Fig. Fig. 1 With the engine idling and the transmission hot pull the transmission dipstick out of the tube



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Fig. Fig. 2 Wipe the dipstick off, then reinsert and remove it again. The level should read in the crosshatch area



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Fig. Fig. 3 If necessary, place a funnel in the dipstick tube and add the proper amount of transmission fluid

Check the automatic transmission fluid level at least every 6,000 miles (7,500 miles for 1975-78 cars). The dipstick can be found in the rear of the engine compartment. The fluid level should be checked only when the transmission is hot (normal operating temperature). The transmission is considered hot after about 20 miles of highway driving.

  1. Park the car on a level surface with the engine idling. Shift the transmission into Neutral and set the parking brake.
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  3. Remove the dipstick, wipe it clean and then reinsert it firmly. Be sure that it has been pushed all the way in. Remove the dipstick again and check the fluid level while holding it horizontally. With the engine running, the fluid level should be between the second notch and the FULL HOT line. If the fluid must be checked when it is cool, the level should be between the first and second notches.
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  5. If the fluid level is below the second notch (engine hot) or the first notch (engine cold), add DEXRON® (1968-75) or DEXRON®II (1976-78) automatic transmission fluid through the dipstick tube. This is easily done with the aid of a funnel. Check the level often as you are filling the transmission, be extremely careful not to overfill it. Overfilling will cause slippage, seal damage and overheating. Approximately one pint of ATF will raise the fluid level from one notch/line to the other.
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Always use DEXRON® or DEXRON®II ATF. The use of ATF Type F or any other fluid will cause severe damage to the transmission.

The fluid on the dipstick should always be a bright red color. If it is discolored (brown or black), or smells burnt, serious transmission troubles, probably due to overheating, should be suspected. The transmission should be inspected by a qualified technician to locate the cause of the burnt fluid.

DRAIN & REFILL/PAN & FILTER SERVICE





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Fig. Fig. 4 To drain the transmission, remove all front and side pan bolts, and all but two rear pan bolts



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Fig. Fig. 5 As you loosen the two rear pan bolts, the pan will lower in the front, allowing more fluid to drain



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Fig. Fig. 6 Inspect the pan for debris. Large pieces of debris laying inside this pan indicate future problems



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Fig. Fig. 7 Once the pan is removed ...



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Fig. Fig. 8 ... remove the transmission filter attaching screws ...



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Fig. Fig. 9 ... then remove the filter. Be careful of any additional fluid which may drain



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Fig. Fig. 10 Be sure to remove the old filter gasket; usually it sticks to the filter mounting surface

The fluid should be changed with the transmission warm. A 20 minute drive at highway speeds should accomplish this.

  1. Raise and support the vehicle on safety stands.
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  3. Depending on the type of transmission the crossmember may have to be removed from the vehicle, in order to remove the fluid pan bolts. If so, be sure to properly support the transmission before removing the crossmember.
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  5. Place a large pan under the transmission pan. Remove all the front and side pan bolts. Loosen the rear bolts about four turns.
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  7. Pry the pan loose and let it drain.
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  9. Remove the pan and gasket. Clean the pan thoroughly with solvent and air dry it. Be very careful not to get any lint from rags in the pan.
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  11. Remove the strainer to valve body screws, the strainer, and the gasket. Most transmissions will have a throw-away filter instead of a strainer. On the 400 transmission, remove the filter retaining bolt, filter, and intake pipe O-ring.
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  13. If there is a strainer, clean it in solvent and air dry.
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  15. Install the new filter or cleaned strainer with a new gasket. Tighten the screws to 12 ft. lbs. On the 400, install a new intake pipe O-ring and a new filter, tightening the retaining bolt to 10 ft. lbs.
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  17. Install the pan with a new gasket. Tighten the bolts evenly to 12 ft. lbs. (8 for Powerglide).
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  19. Lower the vehicle and add the proper amount of DEXRON® or DEXRON®II automatic transmission fluid through the dipstick tube.
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  21. Start the engine in Park and let it idle. Do not race the engine. Shift into each lever position, shift back into Park, and check the fluid level on the dipstick. The level should be 1 / 4 " below ADD. Be very careful not to overfill. Recheck the level after the vehicle has been driven long enough to thoroughly warm up the transmission. Add fluid as necessary. The level should then be at FULL.
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