Crankshaft; Connecting Rods - Mercury 75 Service Manual

Crankshaft

Inspect crankshaft to drive shaft splines for wear.
(Replace crankshaft, if necessary.)
Check crankshaft for straightness. Total maxi-
mum runout for crankshaft is 0.006 (0.15mm).
Replace as necessary.
Inspect crankshaft oil seal surfaces. Sealing sur-
faces must not be grooved, pitted or scratched.
(Replace as necessary.)
Check all crankshaft bearing surfaces for rust,
water marks, chatter marks, uneven wear and/or
overheating. (Refer to "Connecting Rods.")
If necessary, clean crankshaft surfaces with cro-
cus cloth as shown.
Thoroughly clean (with solvent) and dry crank-
shaft and crankshaft ball bearings. Recheck sur-
faces of crankshaft. Replace crankshaft if sur-
faces cannot be properly "cleaned up". If
crankshaft will be reused, lubricate surfaces of
crankshaft with light oil to prevent rust. DO NOT
lubricate crankshaft ball bearings at this time.
WARNING
DO NOT spin-dry crankshaft ball bearing with
compressed air.
4-44 - POWERHEAD

Connecting Rods

If necessary, clean connecting rod surfaces as
follows:
Attach end caps to connecting rods. Following
these directions, tighten rod cap attaching bolts
to specifications. Recheck alignment. Refer to
4-53.
Crocus cloth MUST BE USED to clean bearing
surface at crankshaft end of connecting rod. DO
NOT use any other type of abrasive cloth.
Clean crankshaft end of connecting rod by using
crocus cloth placed in a slotted 3/8 in. (9.5mm) di-
ameter shaft, as shown. Insert shaft in a drill
press and operate press at full speed while keep-
ing connecting rod at a 90_ angle to slotted shaft.
IMPORTANT: Clean connecting rod just enough
to clean bearing surfaces. DO NOT continue to
clean after marks are removed from bearing sur-
faces.
Clean piston pin end of connecting rod, using
same method as above. Use 320 grit carborun-
dum cloth instead of crocus cloth.
Thoroughly wash connecting rods to remove
abrasive grit. Recheck bearing surfaces of con-
necting rods. Replace any connecting rod that
cannot be properly polished. Lubricate bearing
surfaces of connecting rods which will be reused
with 2 cycle engine oil to prevent rust.
51089
51083
90-830234R3 DECEMBER 1997