Chapter 3: Turbocharger & Intake-Exhaust Systems
Covers the air cleaner, intercooler, intake manifolds (SOHC and DOHC), and the factory TD04 turbocharger system — inspection, removal/replacement, and the oxygen sensor. This chapter is the reference base for the Subaru VF25 turbo swap, particularly the oil feed/return and coolant (water pipe A/B) line routing in section 30.
- Air Cleaner System Components — DOHC vs SOHC air cleaner case, element, and duct components.
- Turbocharger Intercooler System — intercooler assembly, bracket, relief hose, and charge-air hoses A/B with clamp orientation notes.
- Intake Manifold SOHC — pre-removal, 17-step removal procedure, and torque specs.
- Intake Manifold DOHC — pre-removal, 18-step removal procedure, torque specs, and manifold face warpage limit.
- Turbocharger System Component Inspection — waste gate solenoid, actuator, and relief valve test procedures with pressure/resistance limits (TD04-specific).
- Turbocharger Replacement — oil pipe/oil pressure switch/oil return line, water pipe A/B, full removal component order, torque specs, and gasket positioning. Primary VF25 swap reference; several torque-to-fastener mappings are flagged unconfirmed — see file for details.
- Oxygen Sensor — DOHC and SOHC removal procedure using special tool MD998770.
Flagged items requiring verification against a clean scan
- 25 — torque-to-fastener mapping for air cleaner clamps (DOHC/SOHC).
- 26 — torque-to-fastener mapping for intercooler hoses/bracket.
- 27 — torque-to-fastener mapping for intake manifold SOHC fasteners.
- 28 — item order for steps 9-10 (Gasket / Attachment Bolt); torque-to-fastener mapping; ambiguous manifold face warpage limit wording (0.15mm vs 0.20mm).
- 29 — solenoid ohm test limit transcribed as “36-442” (read as 36-44 Ω, unconfirmed).
- 30 — full set of turbocharger removal torque values (9 through 49-59 N·m) not mapped to specific fasteners, including the oil pipe/oil return line and water pipe A/B fittings; two fastener-size markings (“N16”/“N6”) unconfirmed; turbocharger gasket orientation diagram not recoverable as text.
- 31 — no oxygen sensor reinstallation torque was present in the scan.