A/T - Primary Oil Pump Housing Production Change
90bmw12 Group 24 Automatic TransmissionBulletin Number 24 02 90 (3098)
Woodcliff Lake, NJ August 1990 Service Engineering
SUBJECT: New Style Primary Oil Pump Housing
MODELS: All Equipped with 4HP22 or 4HP24 Transmissions
Situation: A new style primary oil pump housing has been phased into production since approximately May 1989 transmission production date:
4HP22 - from transmission # 1 113 936 onwards; and 4HP24 - from transmission # 0 029 160 onwards.
On the new style pump housing (Fig. A) the oil return channel is now located between the 8 and 9 o'clock position when looking into the bell housing (see arrow) as compared to the early style (Fig. B) where the oil channel is positioned at the 6 o'clock position.
The front radial oil seal installation depth has also been changed on the new style pump (1 mm deeper than on the early pumps).
A new special seal driver tool has been developed, P/N 88 88 6 240 110, (see also S.I. # 04 09 90 (3090)) which will allow proper installation of both types of radial oil seals. The 1 mm shim (included with the new special tool) should always be used in conjunction with the seal installer tool when installing a radial oil seal in a new style oil pump (Fig. A).
With the 1 mm shim removed from the seal installer tool it may be used on the early style oil pump (Fig. B). These guidelines must be followed whenever replacement of the oil pump radial oil seal is required to assure a quality repair.