upper a nd lower side of t he crescent (1) to the pres-
su re cham ber (6) of the hou sing. Th e m eshin g of the
teeth prevents oil flowing from the delivery side to
the intake side. An exter nal gear (3) is eccentr ically
mounted in the pump housin g. The ext ernal gear is
dr iven by th e inter nal gear (4) which is connected to
the t orque converter h ub.
DISASSEMBLY
(1) Remove pump gears (1 an d 2) (Fig. 186) from
pu mp housing.
(2) Remove the inn er oil pump seal (1) (Fig. 187).
(3) Replace the out er oil pump O-rin g (2) (F ig.
187).
INSPECTION
Before measuring any oil pump com ponents, per-
form a t horough visual in spect ion of all th e compo-
nent s. If any sign of scorin g, scra tches, or oth er
da mage is seen, repla ce the oil pum p a s a n assembly.
SIDE CLEARANCE
Side clearance is the difference bet ween th e th ick-
ness of the pu mp gear s an d the depth of the pocket
in th e pump h ousing. Side clearance can be mea -
su red by laying a flat plate across the mountin g face
of t he pum p housing, and measu ring the dist ance
bet ween t h e pla t e a n d t h e gea r s.
Acceptable side clearance:
• Inner gea r: 0.064 mm (0.0025 in) ma x
• Ou ter gear: 0.069 mm (0.0027 in) max
TIP CLEARANCE
Tip cleara nce is the differen ce between t he tip
diamet ers of the gear teet h and the corresponding
diamet ers of the pocket in the pu mp housing.
Tip clear ance for t he inner gear can be checked by
moving t he inner gear int o tight mesh (2) (Fig. 188)
with the outer gear as shown. Clea rance between th e
ID of the crescent feat ure of t he housing an d th e OD
of t he teeth of t he inner gea r (3) should then me
measu red at a point 37 mm fr om th e corner of th e
crescent (1) feat ure, a s sh own below.
Acceptable tip clearance for inner gear:
• 0.85 mm (0.033 in ) max
Fig. 186 Oil Pump Gears
1 - OUTER PUMP ROTOR
2 - INNER PUMP ROTOR
Fig. 187 Remove Oil Pump Seals
1 - INNER OIL SEAL
2 - OUTER OIL SEAL
Fig. 188 Oil Pump Measurement
1 - MEASURE 37MM FROM THE CORNER OF CRESCENT
2 - TIGHT MESH HERE
3 - MEASURE TIP CLEARANCE HERE
VA AUTOMATIC TRANSMISSION NAG1 - SERVICE INFORMATION 21 - 155
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