Ford Explorer: 4.0 SOHC timing chain 'death rattle' — plastic guides and rear cassette

The 4.0 single-overhead-cam V6 in these Explorers has one famous fault and it is the one that decides whether the vehicle is worth buying. Its timing chain guides are plastic and its tensioners wear out, typically somewhere past 220,000 to 280,000 km, and the result is the noise owners call the death rattle. It starts as a rattle only on a cold start, then rattles all the time, then the engine sounds like a diesel. Two things make it worse than an ordinary chain job. First, this is an interference engine, so a chain that comes off puts the pistons into the valves and ends the engine. Second, one of the chain cassettes sits at the BACK of the engine against the bulkhead, so reaching it means removing the engine — which is why the repair costs a large multiple of the parts and why so many of these were scrapped rather than fixed.

• Rattle from the engine on a cold start, clearing after a few seconds at first
• Rattle that becomes constant, or is loudest around 2,400 to 2,500 rpm under acceleration
• Engine sounding like a diesel once the noise is established
• Misfires or an engine warning light once the chain has jumped teeth
• Rough running, or a no-start after the fact

Be there for a stone-cold start — this is the whole inspection and a seller who has warmed the engine before you arrive has removed the only evidence that matters, so arrange to come back rather than settle. Stand at the front with the bonnet up as it fires and listen hard to the first five to ten seconds: a healthy one is quiet almost immediately, and a rattle or chatter that hangs on is the fault. Then listen at the back of the engine as well, against the bulkhead, because the rear cassette is the expensive one. Once warm, take it for a drive and hold it at around 2,400 to 2,500 rpm under gentle acceleration, listening for a rattle that appears at that speed. Watch for an engine warning light and note any misfire or roughness. Ask the seller plainly whether it rattles on a cold morning and how long it has done so — owners of these know the noise and usually name it. Check the service history for any timing chain work, which transforms the vehicle's value. If a workshop inspection is possible: have the stored codes read for camshaft timing faults.

Parts involved: Timing chain.

$2,500 to $7,000 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.

• “Does it rattle when started on a cold morning, and for how long?”
• “Have the timing chains and guides ever been replaced, and can I see the invoice?”
• “How often has the oil been changed?”

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.