Oil Pump Assembly: Inspection

On all models, check all parts for seal wear, cracks or other damage. Replace any defective parts. Check gear teeth for excessive wear or damage. Replace rubber seal ring. Check clearances of oil pump.
Measure clearance between outer gear and crescent. See Fig 1 . Clearance should be .0055-.0083" (.14-.21 mm). If clearance exceeds .0098" (.25 mm), replace gears.

Fig 1: Measuring Crescent & Outer Gear Clearance
Courtesy of NISSAN MOTOR CO., U.S.A.
Measure clearance between outer gear and pump housing. See Fig 2 . Clearance should be .0020-.0079" (.05-.20 mm). If clearance exceeds .0098" (.25 mm), replace gears.

Fig 2: Measuring Outer Gear & Pump Housing Clearance
Courtesy of NISSAN MOTOR CO., U.S.A.
Use feeler gauge and straightedge to check clearance between gears and pump cover. See Fig 3 . Clearance should be .0008-.0016" (.02-.04 mm). If clearance exceeds .0031" (.08 mm), replace gears or pump housing.

Fig 3: Measuring Pump Gears & Pump Housing Clearance
Courtesy of NISSAN MOTOR CO., U.S.A.
Temporarily reassemble pump housing with inner and outer gears installed. Install pump cover on housing and tighten to specifications. Place pump assembly on a spacer which will allow pump to rotate without deviation.
Mount dial indicator on spacer with indicator point on outer most pump edge. See Fig 4 . Rotate pump 360 degrees and place dial indicator on lowest reading.
Zero indicator and rotate pump 360 degrees. Note the maximum runout reading. Runout should be less than .0028" (.07 mm). Check clearance between seal ring and ring groove.

Fig 4: Checking Oil Pump Runout
Courtesy of NISSAN MOTOR CO., U.S.A.
On L3N71B model, clearance should be .0016-.0063" (.04-.16 mm). Replace seal rings if clearance exceeds .0063" (.16 mm).
On E4N71B, JM600 and L4N71B models, clearance should be .0020-.0079" (.05-.20 mm). Replace seal rings if clearance exceeds .0079" (.20 mm).
NOTE: It is best to replace seal rings during overhaul of transmission.
On all models, check valves for sticking, grooves or burrs. Polish valves with emery cloth if necessary. Replace valve if defective. Check spring and replace if not within specifications. See appropriate PUMP VALVE SPRING CHART.

PUMP VALVE SPRING CHART (CONQUEST & STARION)

Model/App.	Outer Length In. (mm)	Free Length In. (mm)	Installed Length In. (mm)
Lock-Up	.2165 (5.5)	1.035 (26.3)	.63 (16)

PUMP VALVE SPRING CHART (NISSAN PICKUP)

Model/App.	Outer Length In. (mm)	Free Length In. (mm)	Installed Length In. (mm)
Speed Cut	.2638 (6.7)	.945 (24)	.650 (14.2)
Lock-Up	.1949 (4.95)	.925 (23.5)	.650 (14.2)