Mitsubishi Galant Fortis: Timing Chain Tensioner Failure — 4B10/4B11

The 4B10 1.8L and 4B11 2.0L engines use a hydraulic timing chain tensioner that relies on consistent oil pressure and clean oil to maintain chain tension. Neglected oil changes allow sludge to block the tensioner's oil feed, causing the tensioner to lose pressure and the chain to slacken. A slack chain produces a characteristic cold-start rattle that disappears as oil pressure builds. If left unaddressed the chain can skip a tooth or jump timing, causing valve-to-piston contact and catastrophic internal engine damage. Risk escalates significantly beyond 120,000km without tensioner inspection.

• Rattling or clattering from front of engine on cold startup
• Rattle persisting for more than 5 seconds after start
• Check engine light with camshaft position codes
• Rough running or misfires if chain has jumped

1. 1

   Start engine from cold and listen immediately for a chain rattle from the front of the engine — it should not persist beyond 2–3 seconds on a healthy example.

2. 2

   Remove oil filler cap and inspect inside the cam cover for sludge buildup.

3. 3

   Check dipstick oil colour; black sludgy oil indicates neglect.

4. 4

   Ask to see service receipts proving oil changes at factory intervals.

Parts involved: Timing chain.

$600 to $3,500 at New Zealand independent workshop rates. That is for this job on its own, not for the car.

An estimate, in NZD, for the repair as normally carried out. What a specific car costs depends on which part has failed and what it damaged on the way — treat this as the floor for a negotiation, not a quote.

• “Has the timing chain or tensioner ever been inspected or replaced?”
• “Does the engine make any rattling noise when first started cold?”
• “Can you show oil change receipts for the vehicle's full history?”

The failure described above is documented in published sources — owner forums, technical service bulletins, recall notices and workshop write-ups — held in our fault database. The inspection instructions and the cost estimate are KickTyres’ own interpretation of them, and it is a starting point for an inspection rather than a manufacturer statement.