Volvo Penta 300 Series, Руководство по ремонту

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65
Repair Instructions
Camshaft bearings, replacing
The bearings are pressed into position and must be
bored after pressing in. Replacing the camshaft bear-
ings can only be carried out when overhauling the
whole engine.
Oil holes in the bearing
Check when pressing in that the oil hole is opposite
the corresponding oilway in the block.
The front camshaft bearings should be installed with
the groove turned forwards.
Crankshaft and bearing,
inspection
The crankshaft is induction hardened. Crankshaft in-
spection should be carried out very carefully to avoid
unnecessary reconditioning.
Check main and big end bearing shells. Replace worn
bearing shells or those with flecked leaded bronze
coating.
Clean the crankshaft and all channels thoroughly after
removal and inspect it carefully to determine whether
it needs reconditioning as follows.
1
Measure wear and ovalness with a micrometer.
Greatest permitted ovalness in Main and big end
bearings 0.08 mm, maximum conicity 0.05 mm.
Grind the crankshaft to a suitable undersize if these
values are exceeded.
2
Judge any surface damage
3
Measure crankshaft lengthwise runout
Place the crankshaft on a pair of v-shaped blocks
under main bearing journals one and seven. Altern-
atively the shaft can be held in vises. The measure-
ment should be carried out at the fourth main bearing
journal.
The following apply for measured values (total indi-
cated throw)
• <0.2 mm: No corrective action if the wear or sur-
face damage require regrinding
• 0.2–0.7 mm: Align the crankshaft carefully. Be
careful that overalignment does not happen.
NOTE! Do not align more than absolutely necessary.
• >0.7 mm: Scrap the crankshaft, there are risks
that cracks will occur during alignment.
4
Carry out a crack check with the instructions as fol-
lows.