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Perkins 400 series 403C 404C Engine Workshop Service Repair Manual

- Safety first (read and follow these every time)
- Wear eye protection, gloves, and steel-toe boots.
- Work on a flat, level surface and chock wheels if the engine is in a vehicle or boat.
- Disconnect the battery negative terminal to prevent accidental starts or shorts.
- Have a second person available if lifting or positioning the engine; never rely on a single jack or an unstable support.

- What “strut mount” means here (short)
- On Perkins 400-series engines (403C / 404C) the “strut” or “torque” mount is the engine mount that limits fore-aft and torsional movement — it’s usually a rubber-isolated mount or dog-bone style between the engine block and chassis/frame.
- Failure shows as excessive vibration, clunks under load, or visible cracked/flattened rubber or broken metal.

- Parts you may need and why
- Replacement strut mount assembly (complete mount with metal brackets and rubber isolator) — required if rubber is cracked, oil-saturated, torn, or mount is bent/broken.
- Mounting bolts and nuts (grade-matched replacement hardware) — replace if bolts are corroded, stretched, or studs are damaged; many mounts are installed with torque-to-yield or high-strength bolts and should not be reused.
- Washers and locking hardware (new lock washers / nyloc nuts or threadlocker) — ensure proper clamping and prevent loosening.
- Optional: replacement engine mount(s) on other corners if they’re similar age — to restore balanced support.
- How to identify correct part: bring the old mount and engine serial number to a Perkins dealer or check the Perkins workshop parts list; part numbers vary by application (industrial, marine, generator).

- Tools you must have (basic) — each tool explained and how to use it
- Socket set (metric and imperial mix if necessary) with ratchet and extensions
- Description: sockets slip on bolts; ratchet turns them quickly; extensions reach recessed fasteners.
- How to use: choose correct socket size, push fully onto bolt head, use ratchet clockwise/counterclockwise; use a breaker bar for stubborn bolts to avoid breaking the ratchet.
- Combination wrench set (open-end and box-end)
- Description: different length wrenches allow grip in tight places; box end grips more sides of bolt head.
- How to use: fit correct size snugly; pull with steady force; use box end where possible to avoid rounding bolts.
- Torque wrench (click-type or beam)
- Description: applies precise torque to fasteners.
- How to use: set target torque per manual, snug fastener, then use torque wrench until it clicks; calibrate/verify wrench if old.
- Why required: final mounting bolts must be tightened to specification to avoid failure or excessive engine movement.
- Floor jack and jack stands (or engine support bar / hoist)
- Description: jack lifts engine or vehicle; stands hold it securely.
- How to use: position jack under secure lifting point and lift slowly until mounts are unloaded, then place stands on stable points. If lifting engine, use proper lifting bracket and slings or an engine hoist.
- Why required: the engine must be supported when a mount is removed; never rely only on a jack without stands.
- Engine hoist / lift or engine support beam (recommended for engine-out or when mounts support major loads)
- Description: chain hoist or shop crane to support engine weight and prevent tilting.
- How to use: attach to rated lifting points using rated shackles/chains, lift just enough to relieve mount load.
- Why required: some mount positions carry significant load or are difficult to access with only a jack.
- Breaker bar
- Description: long-handled non-ratcheting bar for loosening tight bolts.
- How to use: attach socket, steady push/pull to break loose seized fasteners.
- Why required: engine mount bolts often torqued high or corroded.
- Penetrating oil (e.g., PB Blaster) and wire brush
- Description: helps loosen rusty fasteners; brush cleans threads.
- How to use: soak nuts/studs, let sit, brush flaked rust away, reapply as needed.
- Impact wrench (pneumatic or battery) — optional but makes removal faster
- Description: rapidly applies impacts to break loose bolts.
- How to use: use correct socket, hold securely, short bursts to avoid rounding; don’t use for final torque setting.
- Why optional: useful if bolts are seized; not required if you can use penetrating oil and breaker bar.
- Pry bar and large screwdriver
- Description: used to align holes and lever mounts into place.
- How to use: lever gently to line up mounting holes — do not pry with excessive force that bends brackets.
- Hammer and soft mallet
- Description: helps persuade parts free (soft mallet avoids damage).
- How to use: tap gently to free stuck bracket; protect surfaces with wood block if needed.
- Threadlocker (medium-strength, e.g., blue Loctite) and anti-seize compound
- Description: threadlocker prevents nuts loosening; anti-seize prevents galling on studs.
- How to use: apply per product instructions; use threadlocker on nuts that must not spin loose; use anti-seize on studs that corrode.
- Protective equipment: safety glasses, gloves, hearing protection

- Extra tools that may be required (and why)
- Cut-off tool or grinder (if mount studs are snapped or heavily corroded)
- Why required: to remove irreparably seized studs or welded-on brackets.
- Stud extractor or left-hand drill bits
- Why required: for removing broken studs without destroying threads.
- Thread chase / tap and die set
- Why required: to clean or repair damaged threads in block or bracket before installing new bolts.

- Preparation steps (what to do before starting)
- Gather all tools and replacement part(s) and lay out in order.
- Consult the Perkins 400-series workshop manual for model-specific procedures and torque specs — follow those torque values exactly.
- Take clear photos of the mount location and bolt orientation before removal — helps reassembly.
- Remove surrounding obstructions (hoses, wiring, brackets) enough to access mount bolts safely.
- Apply penetrating oil to fasteners and allow soak time (30–60 minutes or overnight for severe corrosion).

- Removal procedure (general, follow with bullets)
- Support the engine so the strut mount carries no load: position a jack under the oil pan on a wood block or install an engine hoist at rated lifting points; lift slightly until the mount is unloaded (do not lift the engine significantly — just enough to relieve tension).
- Remove any ancillary brackets or components obstructing access to the mount bolts (electrical connectors, heat shields, hoses) and label or photograph them.
- Hold the mating nut/bolt head with a wrench while breaking the bolt free with a breaker bar or impact wrench; remove nuts/bolts carefully — keep hardware separate and note orientation.
- If a stud spins in the block, stop and use a stud extractor, or cut the stud and extract remainder; avoid damaging the block threads — chase threads if needed.
- Remove the mount assembly; if it’s stuck to the frame from corrosion, use penetrating oil, wire brush and a soft mallet or gentle pry to free it.
- Inspect the mount flange faces, block, and frame for distortion or damage; clean mating surfaces with a wire brush.

- Installation procedure (general)
- Compare new mount to old mount for correct orientation and length; some mounts are handed.
- Clean mating surfaces; apply anti-seize to bolt threads if recommended, or light oil on non-threadlocked threads.
- Position new mount and hand-tighten bolts to hold it in place — do not fully torque with engine still unsupported.
- Lower engine slowly onto mount so it carries the load; ensure mounting alignment is correct and holes line up without forcing.
- Tighten bolts finger-tight, then progressively to final torque in the sequence specified in the workshop manual; use a torque wrench for final setting.
- Apply threadlocker to nuts if required by manual; do not use threadlocker where anti-seize is specified.
- Reinstall any removed brackets, hoses, or wiring and reconnect the battery.
- Start engine and observe for abnormal vibration or noises; re-check torque after a short test run per manual guidance.

- Common problems and fixes
- Seized bolts: soak longer with penetrating oil, use breaker bar or impact wrench, heat bolt with propane torch (careful with nearby fuel lines), use stud extractor if broken.
- Broken studs in block: drill out and re-tap or use oversized helicoil/insert if block threads damaged — if you’re a beginner, seek machine shop help.
- Excessive engine movement after replacement: check that all mounts are tight and that other mounts are not worn; inspect engine lifting points for correct positioning.

- Quick tips for a beginner
- Do not remove more than one major mount at once unless the engine is fully supported by a hoist or support bar.
- Replace fasteners that show corrosion or elongation — cheap insurance.
- Always use a torque wrench for final tightening.
- Keep a notebook or phone photos of bolt positions and part orientation.
- If any step requires drilling, tapping, or welding — consider professional help if you’re not experienced.

- Final checks
- Verify torque on all mount fasteners per workshop manual.
- Inspect for fluid leaks or wires that may have been disturbed.
- Road-test or load-test (if generator/marine) and re-check for unusual vibration or loose hardware after initial run.

- Where to get specifics
- Perkins 403C/404C workshop manual and parts list contain exact torque values, bolt grades, and OEM part numbers — obtain the manual from Perkins dealer or official service literature before starting.

- Short summary of what to replace and why
- Replace the strut mount assembly if rubber is degraded, metal brackets cracked/bent, or engine shows excessive movement.
- Replace mounting bolts/nuts if corroded, stretched, or damaged.
- Consider replacing companion mounts of similar age to maintain balanced support.

(End — follow the workshop manual for exact torque figures and model-specific details.)
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