Loader Bobcat 853, 853H. Manual - part 68

PISTON AND CONNECTING ROD (Cont’d)

Assembly

Heat the piston to about 140

°

F (60

°

C) [A].

Assemble the piston and connecting rod [B].

Install the piston to the connecting rod. The piston head
front mark (Item 1) [C] and the connecting rod ‘‘ISUZU’’
casting mark (Item 2) [C] must be facing the same
direction.

Install the piston pin. Install the snap rings [D].

A

B–08251

C

B–08252

1

2

D

B–08195

853, 853H Loader

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B

C–02936

PISTON AND CONNECTING ROD (Cont’d)

Assembly (Cont’d)

Install the rings on the piston [A].

The face with the mark NPR or TOP must be turned up
for the 1st and 2nd compression rings.

Installation

Using a ring compressor tool, compress the rings on the
piston. Make sure the mark is to the front of the engine
and install the piston in the block [B].

Put oil on the bearings. Install the bearing cap [C].

Tighten the nuts to 58–65 ft.–lbs. (78–88 Nm) torque [D].

Rotate the crankshaft to put the other pair of crank pins
at bottom dead center. Repeat the procedure and install
the other pair of pistons.

A

B–08253

Marked Side Up

1st Comp.

2nd Comp.

Oil

C

B–03208

D

B–03325

58–65 ft.–lbs.

(78–88 Nm)

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B

B–03337

CYLINDER LINERS

Checking The Cylinder Bore

The tools listed will be needed to do the following
procedure:

MEL1180 – Puller Set
MEL1261 – Cylinder Liner Remover Ankle

Check the cylinder bore with an inside micrometer. The
checks must be made at parallel and right angles to the
center line of the bore [A].

Measuring point is done approximately 0.75 inch (20 mm)
below the top of the cylinder bore.

Standard – 3.6622–3.6638 inch (93,021–93,060 mm
  Limit – 3.6653 inch (93,10 mm)

Removal

Remove all the parts from the engine.

Using a cylinder liner tool, remove the cylinder liner from
the engine block [B].

There is only one size liner available.

Installation

The tools listed will be needed to do the following
procedure:

MEL1262 – Cylinder Liner Installer

Clean the bore and remove any metal burrs.

Clean the grease from the cylinder liner and dry it.

Use dry ice to cool the cylinder liner, so it will install easier
and smoothly into the engine block.

Using the correct tool, install the cylinder liner [C].

First apply a load of 1103 lbs. (500 kg) using a hydraulic
press.

NOTE: Do Not use a hammer to install the cylinder

liners.

Then, apply a final load of 5513 lbs. (2500 kg). Push the
liner in until 0–0.0039 inch (0–0,10 mm) of the liner is
above the block face [D].

NOTE: The liners are chrome plated and must not be

honed after installation.

Measure the inside diameter of the liner and select the
correct size piston for the liner.

Minimum Diameter

Piston Grade A

3.6622–3.6630 inch

(93,021–93,040 mm)

Piston Grade C

3.6630–3.6638 inch

(93,041–93,060 mm)

Refer to parts fiche when ordering pistons, piston rods
and cylinder liners.

A

B–08223

0.75 ”

(20 mm)

C

B–08225

D

B–08226

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B

B–08224

MAIN BEARINGS

Description

The crankshaft has five main bearings. The end play is
controlled by a thrust washer on both sides of the center
main bearing.

Each main bearing cap has an identification mark in
relation to the engine block [A].

The position of each cap can not be changed from the
original location.

Removal

Remove the oil pan. (See Page 7–81.)

Remove the oil pump. (See Page 7–84.)

Remove the bolts from the main bearing caps.

Remove the main bearing cap and remove the bearing
from the cap half.

Remove the top half of the bearing by pushing on one side
of the bearing half and rotating the crankshaft [B].

On the center main bearing, remove the cap.

Remove the top half of the bearing and thrust washers by
pushing on one side of the bearing and rotating the
crankshaft [C].

A

B–08256

FRONT

C

B–08255

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Service Manual

B

B–01865