Engine Specifications & Details
Chapter divider on printed p.77 lists this section under an in-body numbering of “42–49,” which conflicts with the front-of-manual table of contents (printed p.7-9) that numbers this material 34-41. This site follows the front-matter numbering (34-41) per the assignment; see index.md for the discrepancy note.
Applies to the 4A30 engine, both SOHC (16v, MPI, naturally aspirated) and DOHC (20v, MPI, intercooled turbo — our truck’s configuration) unless a row says otherwise. Two-column spec rows are Limit / Replace as printed; based on cross-checking against the maintenance-note restatements later in this chapter, “Limit” reads as the standard/normal spec and “Replace” as the wear threshold, except where flagged below.
General
| Item | Limit | Replace |
|---|---|---|
| Timing belt | 100,000 km (62,137mi) | Over |
| Valve clearance, cold (Intake) | 0.14mm (0.006in) | — |
| Valve clearance, cold (Exhaust) | 0.20mm (0.008in) | — |
Rocker Arm, Camshaft
| Item | Value |
|---|---|
| Camshaft height (Intake/Exhaust) | 33.81mm (1.331in) / 33.31mm (1.311in) / 33.88mm (1.334in) / 33.38mm (1.314in) — (verify printed p.78) |
(verify printed p.78) — the source table lost its row/column structure for camshaft height. Four numbers were recovered (33.81mm, 33.31mm, 33.88mm, 33.38mm) against labels Intake, Exhaust, Limit, Replace, but which number pairs with which label could not be determined with confidence — do not assume an Intake/Exhaust or Limit/Replace pairing from the order shown. A later maintenance-note restatement (see 36-rocker-arm-camshaft-sohc.md) repeats the identical four numbers with no additional clarity.
Cylinder Head & Valves
| Item | Limit | Replace |
|---|---|---|
| Cylinder head distortion (face) | 0.05mm (0.002in) | Re-surface |
| Cylinder head re-surfacing limit | 0.2mm (0.008in) | — |
| Cylinder head total height | 109-109.1mm (4.291–4.295in) (verify printed p.78) | — |
| Valve margin — Intake | 0.95mm (0.037in) | 0.5mm (0.020in) |
| Valve margin — Exhaust | 1.25mm (0.049in) | 0.7mm (0.028in) |
| Valve length — Intake | 100.04mm (3.939in) | 99.54mm (3.919in) |
| Valve length — Exhaust | 105.48mm (4.153in) | 104.98mm (4.133in) |
| Valve spring free height (all) | 41.15mm (1.620in) (verify printed p.78) | Over |
| Valve spring distortion/warpage (all) | Below 2° | 4° |
| Valve guide-to-stem gap — Intake | 0.02-0.05mm (0.001–0.002in) | 0.10mm (0.004in) |
| Valve guide-to-stem gap — Exhaust | 0.03-0.06mm (0.001–0.002in) | 0.12mm (0.005in) |
| Valve guide length — Intake | 45mm (1.772in) | Over |
| Valve guide length — Exhaust | 56mm (2.205in) | Over |
| Valve guide protrusion height (all) | 17.7-18.3mm (0.697–0.720in) | Over-Under |
(verify printed p.78) — cylinder head total height is scanned as “109-109.1mm” here, but a later maintenance note (38-cylinder-head-valve-system-sohc-dohc.md, printed p.91) restates the same spec as “108.9~109.1mm” — the lower bound conflicts (109 vs 108.9). Do not use either figure until confirmed against a clean scan.
(verify printed p.78) — valve spring free height is scanned here as “41.15mm,” but a later maintenance note (printed p.93) states “Spring Height must be 41.5mm.” These do not match; confirm the correct value before setting up a spring.
Oversize valve guide diameter (all)
| Oversize | Diameter |
|---|---|
| 0.05 OS | 10.61-10.62mm (0.418in) |
| 0.25 OS | 10.81-10.82mm (0.426in) |
| 0.50 OS | 11.06-11.07mm (0.435–0.436in) |
Oversize valve seat diameter
| Oversize | Intake | Exhaust |
|---|---|---|
| 0.03 OS | 23.93-23.95mm (0.942–0.943in) | 21.93-21.95mm (0.863–0.864in) |
| 0.06 OS | 24.23-24.25mm (0.954–0.955in) | 22.23-22.25mm (0.875–0.876in) |
These oversize figures are corroborated by clean restatements elsewhere in the chapter (printed p.95-96) and are used with confidence.
Front Case, Oil Pump, Oil Pan
| Item | Limit | Replace |
|---|---|---|
| Oil pump rotor clearance gap (all) | 0.06-0.18mm (0.002–0.007in) | Over-Under |
| Oil pump side clearance (all) | 0.04-0.11mm (0.002–0.004in) | Over-Under |
| Oil pump body distortion (all) | 0.10-0.17mm (0.004–0.007in) | 0.35mm (0.014in) (verify printed p.79) |
(verify printed p.79) — the 0.35mm replace figure for oil pump body distortion is only present in this table; it is not independently restated in the 39-oil-pump.md maintenance notes. Not contradicted, just unconfirmed — flag before using as a hard replace threshold.
Piston & Connecting Rods
| Item | Limit | Replace |
|---|---|---|
| Piston pin press requirement | 4900-10,780 N | — |
| Piston ring side clearance — No.1 | 0.03-0.07mm (0.001–0.003in) | 0.1mm (0.004in) |
| Piston ring side clearance — No.2 | 0.02-0.06mm (0.001–0.002in) | 0.1mm (0.004in) |
| Piston ring gap — No.1 | 0.15-0.30mm (0.006–0.012in) | 0.8mm (0.031in) |
| Piston ring gap — No.2 | 0.30-0.50mm (0.012–0.020in) | 0.8mm (0.031in) |
| Piston ring gap — Oil ring | 0.15-0.45mm (0.006–0.018in) | 1.0mm (0.039in) |
| Connecting rod (big end) clearance | 0.10-0.25mm (0.004–0.010in) | 0.4mm (0.016in) |
| Crankshaft pin oil clearance | 0.02-0.04mm (0.001–0.002in) | 0.1mm (0.004in) |
Crankshaft, Cylinder Block
| Item | Limit | Replace |
|---|---|---|
| Crankshaft endplay | 0.05-0.25mm (0.002–0.010in) | 0.04mm (0.002in) (verify printed p.79) |
| Crankshaft journal oil clearance | 0.02-0.03mm (0.001in) | 0.1mm (0.004in) |
| Cylinder block deck distortion (warpage) | 0.05mm (0.002in) | 0.4mm (0.016in) |
| Cylinder block deck surfacing limit | 0.2mm (0.008in) | — |
| Cylinder diameter (STD) | 60.0mm (2.362in) | — |
| Cylinder distortion limit | Below 0.01mm (0.0004in) (verify printed p.79) | — |
(verify printed p.79) — crankshaft endplay’s “Replace” figure of 0.04mm is smaller than the stated Limit range’s own lower bound (0.05mm), which is backwards for an endplay wear spec (replace threshold should normally be a maximum that endplay must not exceed). This value may belong to a different row entirely; do not use 0.04mm as an endplay replace limit without checking the printed page.
(verify printed p.79) — cylinder distortion limit is scanned here as “Below 0.01mm,” but the maintenance note on printed p.113 states “Distortion Limit: .1mm” (i.e., 0.1mm) — a full order-of-magnitude conflict. Confirm against a clean scan before machining or measuring to this spec.
Piston-to-cylinder clearance — SOHC vs DOHC
| Configuration | Clearance |
|---|---|
| STD / non-turbo (SOHC) | 0.02-0.04mm (0.001–0.002in) |
| Turbo (DOHC — our truck) | 0.03-0.05mm (0.001–0.002in) |
This figure is corroborated by a clean restatement in 41-crankshaft-cylinder-block.md (printed p.113) and is used with confidence. Our 4A30 DOHC turbo uses the wider 0.03-0.05mm clearance, not the SOHC 0.02-0.04mm figure.
Turbocharger — DOHC only
| Item | Value |
|---|---|
| Waste gate actuator opening pressure | 78 kPa (11 psi) |
No SOHC equivalent exists; this spec applies only to the DOHC turbo engine (our truck).
