Connecting Rod Oil Clearance - Mercury 25 EFI Service Manual

2. The journal size of the cylinder block is stamped with a code letter on the upper end of the cylinder block.
3. Use the color coded main bearing that matches the main bearing code letters on the cylinder block.
Code Letter
A
B
Code Letter
A
B

Connecting Rod Oil Clearance

Measure the connecting rod oil clearance using the measurement steps outlined following.
Connection Rod
Oil Clearance
Connecting Rod Oil Clearance Measurement
IMPORTANT: Do not interchange connecting rod caps. Reinstall connecting rod caps in their original positions.
1. Clean all the oil from the connecting rod bearing surfaces and connecting rod journals on the crankshaft.
2. Install the connecting rod to the crankshaft.
IMPORTANT: Install connecting rods in their original locations (#1, #2 and #3). Make sure that the "UP" mark on the
connecting rod cap faces towards the flywheel end of the crankshaft.
3. Place a piece of plastigauge on the crankpin journals.
90-8M0105568 eng MARCH 2016
a -
Cylinder Block Main Bearing Code
Dimension
39–39.008 mm (1.53543–1.53575 in.)
39.008–39.016 mm (1.53575–1.53606 in.)
Bearing Thickness
Dimension
1.488–1.494 mm (0.05858–0.05882 in.)
1.494–1.500 mm 0.05882–0.5906 in.)
0.015–0.041 mm (0.0006–0.0016 in.)
© 2016 Mercury Marine
Main bearing journal letter code
3147
Cylinder Block/Crankcase
Bearing Color
Blue
Red
Bearing Color
Blue
Red
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