Pistons & Connecting Rods

Applies to all engine variants (SOHC and DOHC) — the manual heads this section “Pistons & Connecting Rods: All.”

Component removal order

1. Nut
2. Connecting rod cap
3. Connecting rod bearing
4. Piston & connecting rod
5. Connecting rod bearing
6. Piston ring No.1
7. Piston ring No.2
8. Oil ring
9. Piston pin
10. Piston
11. Connecting rod
12. Bolt

Connecting rod bolt torque (as scanned)

The diagram shows a fragment: “13±2 4m” / “+80°-84°” next to item 12 (bolt).

(verify printed p.102) — this reads as a possible torque-to-yield (TTY) spec: an initial torque figure (garbled — could be 13±2 N·m or similar) followed by an additional rotation angle of 80°-84°. Neither the base torque number nor the angle range should be treated as confirmed; the OCR could not cleanly separate digits from the surrounding balloon numbers (“12,” “1,” “26,” “11”). Do not torque connecting rod bolts to a guessed value — confirm against a clean scan before overhaul.

Piston pin removal

Tools required:

• MD991539 — Guide A
• MB991540 — Guide B
• MB991538 — Guide C / push rod

Procedure: place tools Guide A and Guide C as shown, place the piston assembly on piston base MD999583, and press out the piston pin.

Note: Always use connecting rods from their original cylinder location. If a new rod is used, mark the cylinder location as shown.

Piston pin installation

Same tool set as removal (Guide A/B/C, push rod).

Note: The “Front Mark” must correspond on both the piston and connecting rod as shown.

Note: Cylinder bore/piston size markings are stamped on the piston. If boring or piston sizes have changed, stamp out old markings and re-stamp with the new size.

Required press force: 4900-10,780 N (matches the Engine Specifications table — confirmed).

Oil ring installation

Note: Proper oil ring installation is required to prevent excessive oil consumption. The two side rails and spacer must be installed as shown.

Note: Side rails should be opposite as shown in the diagram — ring gap at the 6 o’clock position, side rails at 9 & 3 o’clock.

Ring identification (oil ring side rail)

Size	Color mark
STD	N/A (no mark)
0.25mm OS	Blue stripes (2)
0.50mm OS	Yellow stripe (1)

Ring identification (compression rings)

Size	Mark
STD	No mark
0.25mm OS	”25”
0.50mm OS	”50”

Ring position codes: 1R = top ring, 2R = second ring.

Connecting rod bearing size marks

Note: Factory size bearing markings are stamped on the crankshaft, as shown in the diagram. Check the Parts Manual for updates and changes to markings.

(verify printed p.106) — the bearing color-code table lost its row/column alignment in OCR. Recovered fragments suggest three size bands identified by tick-mark count (|, ||, |||) crossed with a color (Brown, No Color, Blue/White), against three connecting-rod pin diameter ranges:

Pin diameter range (as scanned)
35.995-36.000mm (1.4171–1.4173in)
35.985-35.995mm (1.4167–1.4171in)
35.980-35.985mm (1.4165–1.4167in)

Do not assign a specific color/mark combination to a specific pin-diameter range from this table — the OCR order does not reliably preserve which color goes with which range. Confirm against a clean scan or the Parts Manual before selecting a replacement bearing.

Piston/ring installation to block

Note: Ensure side rail (ring gaps) are facing the proper direction for installation. Coat the piston and rings heavily with assembly lube and/or 30W SAE engine oil. Never install pistons “dry” — failure will occur.

Note: Use a proper ring compressor to install pistons into the block. Use a wooden hammer handle or plastic tap rod. Never use a steel or brass handle to install pistons.

Piston ring side gap (confirm before installation):

Ring	Gap
No.1 (R1)	0.03-0.07mm (0.001–0.003in)
No.2 (R2)	0.02-0.06mm (0.001–0.002in)

Connecting rod bearing cap

Note: Ensure caps and bearings are correct for each connecting rod. Grease and install.

Clearance inspection

1. Rotate engine two full rotations.
2. Inspect clearance.

Limit: 0.10-0.25mm (0.004–0.010in) — matches the Engine Specifications table’s Connecting Rod (Big End) Clearance figure; confirmed.