Crank Mechanism - Volvo MD2010 Workshop Manual

Engine body

Crank mechanism

Dismantling of crankshaft
(engine removed)
1.
Dismantle the reverse gear alt. S-drive and adapter
plate and coupling, flywheel and flywheel housing.
2.
Remove the cylinder head. See under heading
"Dismantling of the cylinder head" on pages 25
and 26.
3.
Remove the valve lifters and place them in order in
a rack.
4. Remove the pistons with connecting rods. Carry
out the work steps to item 5 under the heading
"Dismantling of piston, piston rings and connecting
rod" on pages 34 and 35.
5. Remove the timing gear casing. Carry out the work
steps to item 8 and item 10 under the heading "Dis-
mantling of timing gears" on pages 40 and 41.
Fig. 71. Dismantling of main bearing cap
6. Remove the lock screws which hold the main bear-
i ng cap (Fig. 71). Carefully lift off the crankshaft
complete with cap backwards.
Note: Tape the crankshaft gear to protect the bear-
i ng surfaces in the block during dismantling.
7.
Remove the main bearing cap from the crankshaft.
MD2040: Take care of both thrust washers in the
rear cap.
4 6
Inspection of crankshaft
Clean the crankshaft carefully in all channels after dis-
mantling and inspect it very carefully to confirm whether
it really need renovating.
1 2 1 2
Qum
Fig. 72. Check measurement of crankshaft
1. Check the wear and out-of-roundness with a mi-
crometer. Measure the diameters "A-A" and "B-B"
i n items "1" and "2" (See Fig. 72).
The max. permissible conicity and out-of-roundness
on the main and big-end bearings is 0.05 mm
(.0019 in). Grind the crankshaft to an appropriate
undersize if these values are exceeded. Bearing
cups are available in two oversizes.
2.
Measure the crankshafts longitudinal curvature
(distortion). Place the crankshaft on a pair of V-
blocks placed under the front and rear of the main
bearing journal. Alternatively the shaft can be
braced between spikes. Measuring should be car-
ried out on the middle main bearing journal(s).
Max. longitudinal curvature (distortion): 0.06 mm
(.0023 in).
If this value is exceeded the crankshaft must be
aligned or replaced.
3.
Check that the mating surfaces on crankshaft seals
are not worn or damaged.