REAR SEAL AREA LEAKS
Since it is sometimes difficult to determine the source of an oil leak in the rear seal area of the engine, a more
involved inspection is necessary. The following steps should be followed to help pinpoint the source of the leak.
If the leakage occurs at the crankshaft rear oil seal area:
1. Disconnect the battery.
2. Raise the vehicle.
3. Remove torque converter or clutch housing cover and inspect rear of block for evidence of oil. Use a black light
to check for the oil leak:
a. Circular spray pattern generally indicates seal leakage or crankshaft damage.
b. Where leakage tends to run straight down, possible causes are a porous block, camshaft bore cup plugs, oil
galley pipe plugs, oil filter runoff, and main bearing cap to cylinder block mating surfaces. See Engine, for
proper repair procedures of these items.
4. If no leaks are detected, pressurized the crankcase as outlined in the section, Inspection (Engine oil Leaks in
general)
CAUTION: Do not exceed 20.6 kPa (3 psi).
5. If the leak is not detected, very slowly turn the crankshaft and watch for leakage. If a leak is detected between
the crankshaft and seal while slowly turning the crankshaft, it is possible the crankshaft seal surface is damaged.
The seal area on the crankshaft could have minor nicks or scratches that can be polished out with emery cloth.
CAUTION: Use extreme caution when crankshaft polishing is necessary to remove minor nicks or
scratches. The crankshaft seal flange is specially machined to complement the function of the rear oil seal.
6. For bubbles that remain steady with shaft rotation, no further inspection can be done until disassembled. (Refer
to 9 – ENGINE – DIAGNOSIS AND TESTING), under the Oil Leak row, for components inspections on possible
causes and corrections.
7. After the oil leak root cause and appropriate corrective action have been identified, (Refer to 9 –ย ย ย ย ย ย ย ย ย ENGINE/ENGINE BLOCK/CRANKSHAFT OIL SEAL – REAR – REMOVAL).