Isuzu KB P190. Manual - part 761

Engine Mechanical – V6 

Page 6A1–267 

 

Page 6A1–267 

CAUTION

 

Do not damage the crankshaft journal, 
cylinder wall and piston cooling jets when 
removing the connecting rod and piston 
assembly. 

12 

Using connecting rod guide pin set, Tool No.  
EN-46121 (1), push the connecting rod and piston 
assembly (2) through the top of the cylinder. 

 

 

 

Figure 6A1 – 467 

CAUTION

 

When dismantled, ensure the connecting 
rod, connecting rod cap, piston and 
bearings are organised in their original 
position and location. This will also aid 
engine mechanical diagnosis. 

13 

Remove connecting rod guide pin set, Tool No.  
EN-46121 (1) from the connecting rod bolt holes. 

14 

Remove the upper connecting rod bearing from the 
connecting rod (2). 

 

 

 

Figure 6A1 – 468 

15 

Remove the lower connecting rod bearing (1) from 
the connecting rod cap (2). 

 

Figure 6A1 – 469 

Engine Mechanical – V6 

Page 6A1–268 

 

Page 6A1–268 

N O T E  

The cap and rod are a matched set and must be 
kept together. 

16 

Reattach the connecting rod cap (1) to the connecting 
rod (2) to prevent damage to their mating surfaces. 

17 

Repeat steps 4 to 16 for the remaining piston and 
connecting rod assemblies. 

 

 

 

Figure 6A1 – 470 

Disassemble 

CAUTION

 

A piston ring expander must be used to 
remove and install the piston rings. Only 
expand the rings far enough to fit over the 
piston lands. If the rings are overexpanded, 
the top ring will shatter and the others will 
distort. 

1 

Remove the piston rings (2) using a piston ring 
expander (1). Place each ring in a clean shop towel 
for storage. 

 

 

 

Figure 6A1 – 471 

CAUTION

 

Do not reuse the piston pin retainers. 

2 

Remove the piston pin retainers by using the removal 
access notch (1) in the side of the piston. Discard the 
piston pin retainers. 

 

 

 

Figure 6A1 – 472 

Engine Mechanical – V6 

Page 6A1–269 

 

Page 6A1–269 

3 

Slide the piston pin (1) out of the piston (2). The 
piston will disconnect from the connecting rod. 

 

 

Figure 6A1 – 473 

Clean and Inspect 

Piston Cleaning Procedure 

CAUTION

 

Do not use a wire brush to clean any part of 
the piston. 

1 

Clean the piston skirts and the pins with a suitable solvent. 

2 

Clean the piston ring grooves with a groove cleaner. Ensure the oil ring holes and slots are clean. 

 

Safety glasses must be worn when using 
compressed air. 

3 

Dry the piston with compressed air. 

Piston Inspection Procedure 

1 

Inspect the pistons for the following conditions: 
• 

eroded areas at the top of the piston (1), 

• 

piston pin retainer grooves for burrs (2), 

• 

worn piston pin bores or worn piston pins (3), 

• 

scuffed or damaged skirt coating (4), 

• 

ring grooves for cracks, nicks or burrs that may 
cause binding (5), and 

• 

warped or worn ring lands. 

2 

Replace pistons that show any signs of damage or 
excessive wear. 

 

Figure 6A1 – 474 

Engine Mechanical – V6 

Page 6A1–270 

 

Page 6A1–270 

Piston Measurement 

1 

Measure piston width using the following procedure: 

a 

Using an outside micrometer, measure the 
width of the piston at 30 mm below the crown 
top (1), at the thrust surfaces of the piston, 
perpendicular to the piston pin centreline. 

b 

Compare the measurement of the piston to its 
original cylinder by subtracting the piston width 
from the cylinder diameter. 

c 

Check your measurements with specifications, 
refer to 

5  Specifications

. 

d 

If the clearance obtained through measurement 
is greater than the provided specifications and 
the cylinder bores are within specification, 
replace the piston. 

 

Figure 6A1 – 475 

2 

Measure the piston pin bore to piston pin (2) 
clearances using the following procedure: 

a 

Piston pin bores and pins must be free of 
varnish or scuffing. 

b 

Use an outside micrometer (1) to measure the 
piston pin in the piston contact areas. 

 

Figure 6A1 – 476 

3 

Using an inside micrometer, measure the piston pin 
bore (1). Compare the result with the piston pin 
diameter and piston pin to piston pin bore clearance 
listed in the specifications, refer to 

5  Specifications

. 

4 

If the clearance is excessive, determine which piece 
is out of specification and replace as required. 

5 

Replace the piston if any of its dimensions are out of 
specification. 

6 

If the new piston does not meet clearance 
specifications, the cylinder block may need to be 
oversized to 0.25 mm. There is only one size of 
oversized pistons and rings available for service. 

 

Figure 6A1 – 477