The short answer

Generation	Years	Engine	Belt or chain?	Scheduled service?
GX470	2003-2009	2UZ-FE 4.7L V8	Timing belt	Yes, every 90,000 miles or 108 months1
GX460	2010-2023	1UR-FE 4.6L V8	Timing chain	No replacement interval
GX550	2024+	V35A-FTS 3.4L twin-turbo V6	Timing chain	No replacement interval

The belt vs chain split is the reason GX470 buying threads obsess over service records while GX460 buying threads obsess over cold-start noises. Same part of the engine, completely different maintenance story.

GX470 (2003-2009): timing belt, and it has a deadline

The 2UZ-FE 4.7L V8 in the GX470 uses a rubber timing belt that runs dry, outside the oil pan, driving the two camshafts and the water pump. Rubber ages whether you drive the truck or not, so Lexus put a calendar on it: every 90,000 miles or 108 months.¹

Two things make this the most expensive scheduled service on a GX470:

1. The water pump rides the belt. The pump is on the belt path, so it gets replaced with the belt as a matter of course. The standard owner approach is the Aisin TKT-021 kit, which bundles the belt, water pump, hydraulic tensioner, idlers, and gaskets.⁸
2. On 2005 and later trucks, a snapped belt can kill the engine. The 2UZ-FE gained VVT-i in 2005, and the factory manual warns that turning the valvetrain at the wrong angle can slam valves into pistons. Owners report the VVT-i engines (2005-2009) are interference: a broken belt means bent valves. The 2003-2004 pre-VVT-i engines are widely regarded by owners as non-interference, but that is owner consensus, not a factory statement.²

The community adds a stricter time rule on top of the factory interval: roughly every 6 to 7 years regardless of mileage, because a low-mile truck still has a belt degrading on the same schedule.¹ If you are buying a GX470 with no receipt or service history showing the belt was done, assume it was not done. That is the standard advice, and it is the correct advice.

The full procedure, parts list, and torque specs live in our companion guide: 2UZ-FE Timing Belt + Water Pump: The 90k-Mile Service. This guide does not repeat that procedure. Read it before you buy, and read it again before you wrench.

Shadetree note: the belt sticker on the timing cover is the first thing to check on any used GX470. No sticker and no records means you budget for the job immediately. Our GX buying guide has the full pre-purchase checklist.

GX460 (2010-2023): timing chain, and there is no interval

The 1UR-FE 4.6L V8 in the GX460 uses a steel timing chain that runs inside an oil-tight cover, bathed in engine oil. The factory service manual for the GX460 references the timing chain 52 times and the timing belt zero times. There is no belt to change, and Lexus publishes no chain replacement interval.³

“No interval” does not mean “nothing ever wears.” The chain itself is the most durable part of the system. The parts around it are not:

• Tensioners. They are fed by engine oil pressure, so they are only as healthy as your oil. Lexus issued TSB EG-0031L-0516 for a clattering noise from the timing chain during warm-up idle, traced to the no.1 left-hand chain tensioner. The TSB applies to GX460s built before the April 2016 production change (the tensioner was revised from 13540-38041 to 13540-38042). If a 2010-2015 truck rattles for a few seconds on a cold start, this is the first suspect.⁴
• Guides. The chain runs against plastic-faced guides and slippers. They wear and crack with age and with long oil change intervals. They are ordinary cataloged service parts for the GX460.
• Chain stretch. Past 200k miles a chain can elongate enough to retard cam timing, which eventually sets cam correlation codes. Watch for symptoms instead of a schedule.
• Timing cover seep. The cover seals oil in, so seepage at the seam is the chain-engine equivalent of a belt-engine cam seal leak. Owners have documented full reseal jobs, and they are a serious teardown. Lexus’s own oil-leak bulletin (L-SB-0002-20) defines a seep as a thin accumulation of oil and calls seepage a normal condition that does not require repair, so a damp seam on a used truck is a bargaining point.⁶

Two GX460 specifics worth knowing before you buy:

• The water pump is a timing-cover job. On the 1UR-FE the water pump sits behind the timing cover, driven by the chain. When it fails you are opening the front of the engine, a much bigger job than a belt-drive water pump. Parts vendors sell the chain kit and water pump as a single set for exactly this reason.⁵ A weeping water pump on a GX460 is a bigger deal than a weeping one on a GX470. Budget and plan accordingly.
• The accessory belt still wears out. Chain drive covers only the timing system. The serpentine belt, tensioner, and idlers on the front of the engine are still rubber and still need replacement on condition.

Shadetree note: to check a cold GX460 for chain rattle, have someone start it stone cold while you listen at the front of the engine. Owners report the noise gets louder with the oil filler cap off, which points at the valvetrain rather than accessories. Some owners quiet a mild rattle by switching from 0W-20 to 5W-30. That comes from owner threads. It quiets the noise without fixing the worn tensioner.

GX550 (2024+): timing chain, on a brand-new platform

The GX550’s V35A-FTS 3.4L twin-turbo V6 uses a chain drive. The engine specification lists the valve mechanism as 24-valve DOHC, chain drive, with VVT-iE on the intake cams and VVT-i on the exhaust cams.⁷ Like the GX460, there is no scheduled chain replacement.

That is about all that can be said with confidence right now. There is no GX550 factory manual on file, so water pump location, interference behavior, and long-term chain wear patterns are not verified. The V35A-FTS is a young engine family in a young truck. The honest position: the chain needs no scheduled service, and the long-term data is still coming in. Anything more specific would be guessing.

What “lifetime chain” actually promises, and what it does not

“Lifetime chain” is a marketing phrase, not an engineering warranty. Here is the honest version:

• It promises you will never have a 90k-mile appointment with a $1,000 belt job. The chain is designed to last the life of the engine under normal maintenance.
• It does not promise the tensioners, guides, and water pump will last forever. Those are wear parts that live or die by oil quality and oil change frequency.
• It does not promise silence. Chain systems make noise when tensioners get weak, and diagnosing that noise is a real skill on a used-truck inspection.
• It does not cover the accessory belt, which is still rubber and still fails with age.

The practical takeaway: on a chain engine, your oil change habits are your timing system maintenance. The tensioners are oil-pressure fed, the chain runs in the oil, and dirty oil wears everything it touches. Owners who run 5,000-mile intervals instead of the 10,000-mile spec are, in effect, doing timing chain preventive maintenance. Our GX fluids guide covers the oil side of that equation.

Buyer checks, by generation

GX470: check the timing cover for a belt-change sticker with a date and mileage, then verify against service records. Pull the VIN service history on the Lexus owners site. No sticker and no records means you budget for a belt and water pump job on day one. Full pre-purchase list in the GX buying guide.

GX460: cold-start the truck yourself and listen for chain rattle from the front of the engine during the first minute. Ask about oil change intervals and what viscosity the owner runs. Check the timing cover seam and the valley area for seepage. A 2010-2015 truck with a persistent warm-up rattle may want the updated tensioner from Lexus TSB EG-0031L-0516.

GX550: too new for pattern failures. Confirm the truck has a clean service history and leave the chain alone.

Parts and tools

This guide is inspection and buying advice, not a procedure, so the kit list is short. If the inspection above sends you toward a timing job, these are the kits owners buy. Confirm against your VIN before ordering.

Timing kit	GX470 (2003-2009, 2UZ-FE)	GX460 (2010-2023, 1UR-FE)	GX550 (2024+, V35A-FTS)
Belt or chain kit with water pump	Aisin TKT-021 timing belt kit (Amazon)	DNJ TK978AWP timing chain kit with water pump (eBay)	Verify by VIN

For the checks above:

• Streamlight Stylus pen light, for reading the belt sticker and checking the timing cover seam for seepage.
• Lisle 52500 mechanic’s stethoscope, for pinpointing cold-start chain rattle on a GX460. Shadetree alternative: a long screwdriver held to the ear with the tip on the timing cover, kept clear of the belt and fan.
• Scott Shop Towels, for the seep check. Lexus’s own diagnostic method is to press a dry paper towel to the damp area: if it stays dry, the seep is old; if it wets, it is current.
• The VIN and the Lexus owners site, for pulling dealer service history before you believe a seller’s word about the belt.
• BlueDriver Bluetooth OBD-II scanner, for checking cam correlation codes on high-mile chain engines.

If the inspection points at a timing job instead of just a look, the supporting parts owners buy alongside the kits:

• GX470: Toyota Super Long Life Coolant (pink, 00272-SLLC2) for the refill, and OEM camshaft and crankshaft front seals (crank 90311-A0001, VVT-i cam 90311-71002) while the front cover is off.
• GX460: updated OEM LH timing chain tensioner 13540-38042 from the TSB above, Toyota FIPG 00295-00103 for the timing cover reseal, and a Bando serpentine belt while the front of the engine is apart.

If the GX470 belt job is in your future, the full parts list (Aisin TKT-021 kit, seals, crank pulley holder tool) lives in 2UZ-FE Timing Belt + Water Pump: The 90k-Mile Service.

FAQ

Does the GX460 have a timing belt or a timing chain?
A timing chain. The GX460’s 1UR-FE 4.6L V8 is chain driven, and Lexus publishes no replacement interval for it.

When do I change the timing belt on a GX470?
Every 90,000 miles or 108 months, per Lexus. Many owners do it closer to every 6 to 7 years regardless of mileage. Do the water pump at the same time.

Does the GX550 have a timing belt or a timing chain?
A timing chain. The V35A-FTS twin-turbo V6 is chain driven per the factory engine specification.

What happens if the timing belt breaks on a GX470?
On 2005-2009 VVT-i trucks, the engine is interference: a snapped belt can bend valves. On 2003-2004 trucks, owners widely regard the pre-VVT-i engine as non-interference, so a break is usually just a tow bill. Either way, do not run the interval.

My GX460 rattles for a few seconds on cold start. Is that the timing chain?
It can be. The usual suspect is a weak chain tensioner, and Lexus issued TSB EG-0031L-0516 for warm-up idle clatter on GX460s built before April 2016. Listen with the oil cap off to confirm it is valvetrain noise, then have it diagnosed.

Do timing chains ever need to be replaced?
Yes, but on condition, not on a schedule. Worn tensioners, cracked guides, or a stretched chain past 200k miles can all force a timing job. Watch for noise or cam correlation codes. There is no mileage number to follow.

Sources

• Toyota/Lexus factory service manual, 2005 GX470 (2UZ-FE timing belt service)
• Lexus factory service manual, 2013 GX460 (1UR-FE timing chain system)
• Lexus TSB EG-0031L-0516: UR engine timing chain clatter during warm-up idle, March 2016
• Lexus TSB L-SB-0002-20 (NHTSA-hosted PDF): Oil Leak Diagnosis and Repair, Rev 1, February 4, 2020
• Toyota V35A-FTS engine specification: valve mechanism 24-valve DOHC, chain drive (http://zatonevkredit.ru/repair_manuals/raw_content/AWJINAD3rzlLPWuuWJjr)
• IH8MUD: Has anyone here done the Timing Chain Cover leak fix themselves? (https://forum.ih8mud.com/threads/has-anyone-here-done-the-timing-chain-cover-leak-fix-themselves.1304232/)
• IH8MUD: Strange noise at first start up of the day and low coolant levels (https://forum.ih8mud.com/threads/two-part-question-2008-toyota-landcruiser-strange-noise-at-first-start-up-of-the-day-low-coolant-levels-hopefully-reservoir-will-remain-full-now.1267398/)
• IH8MUD: Timing belt/water pump consequences (https://forum.ih8mud.com/threads/timing-belt-water-pump-consequences.939734/)
• Tundras.com: What is this noise from left side of engine bay? (https://www.tundras.com/threads/what-is-this-noise-from-left-side-of-engine-bay-timing-chain-tensioner-or-belt-tensioner-pulley.80917/)
• ClubLexus: Clicking sound upon cold start (https://www.clublexus.com/forums/ls-4th-gen-2007-2017/1055002-clicking-sound-upon-cold-start.html?s=d53b3cf0bd47d4eadce70fc9df504a99)
• Partsology: DNJ timing chain kit with water pump, 2010-2021 4.6L (https://partsology.com/products/dnj-engine-timing-chain-kit-with-water-pump-lexus-toyota-gx460-sequoia-tundra-1ur-fe-dohc-tk978awp)
• LexusPartsNow: 2013 GX460 timing chain guide parts (https://www.LexusPartsNow.com/oem-2013-lexus-gx460-timing_chain_guide.html)

Footnotes