A/T Oil Pump Seal Assembly - Leaking

Number 83-T-38 Section 7 Date 06/83
Subject: OIL PUMP SEAL ASSEMBLY LEAKING - ALL THM 700-R4 TRANSMISSIONS

Figure 1:

Beginning March 7, 1983, all THM 700-R4 transmissions were built with a revised oil pump body (part number 8642986). As shown in Figure 1 below, the oil drainback passage in the revised pump body connects with one of the core slots. This design change allows for more effective oil drainback, thereby relieving pressure under the oil seal assembly..
SERVICE INFORMATION

When servicing a THM 700-R4 built prior to this change which either: (1) pushes the oil seal assembly out of the pump body; or, (2) forces oil past the lip of the seal around the converter hub, correct the drainback restriction as follows:

1. Following the Service Manual procedure, remove and disassemble the oil pump assembly..

Figure 2:

2. Place the oil pump body on a cloth to protect the oil passage face. With a 6.0 mm (1/4") drill bit, enlarge the hole at point "A" to a depth of 12.9 mm (1/2") maximum (see Figure 2 shown on the reverse side). Hole "A" must connect with the drainback passage (refer to Figure 2).

3. Turn the pump body over and inspect the drainback passage at point "B" (refer to Figure 2). If the drainback passage is restricted at point "B" (i.e., the two passages do not meet evenly), use a 8.0 mm (3/8") drill bit and enlarge the passage to point "C". Do not drill any deeper than necessary to remove the restriction.
4. Clean out any metal chips and reassemble the oil pump using the Service Manual procedure.