Used Mercedes-Benz GLS Timing Chain

Yes, all Mercedes-Benz GLS variants use a timing chain rather than a timing belt — this applies across the full GLS range including the petrol and diesel engines fitted to the X166 (2016–2019) and X167 (2019-onwards) generations. Unlike a belt, the chain is designed to last the life of the engine under normal conditions, though wear, stretch, and tensioner or guide failures do occur and replacement is a recognised repair on these engines. So if you need this part, you are looking in the right place.

The 2017 GLS sits in the first-generation X166 (2016–2019), while a 2019 GLS could be either the late X166 or the new-generation X167 that launched in 2019, and the two generations use different engine families, so the chain itself is unlikely to interchange between them. The safest approach is to confirm your engine code — found on your V5 or via a VIN check — and supply it to the breaker, who can match the donor vehicle's engine code directly to yours. Engine code above all else is what determines whether a timing chain will fit.

Yes, engine code is the single most important detail for this part — the GLS has been offered with a range of petrols and diesels across its generations, including six-cylinder and V8 units, and the timing chain components differ between them. Get your engine code from your V5 registration document or a VIN check, and give it to the breaker so they can match it precisely to the donor vehicle. Do not rely on engine size alone, as different variants can share a displacement but use different chain configurations.

Trim level does not affect timing chain fitment — what matters is the engine code, not whether your car is badged AMG Line, Sport, or a full AMG 63. The AMG 63 does use a different engine (the M177 twin-turbo V8) compared to standard GLS variants, so if you have that model the breaker needs to source from a matching AMG 63 donor, but that is driven by the engine code, not the trim name itself. Give the breaker your engine code and they will identify the correct chain regardless of what the badge says.

The 2021 GLS 400d sits in the X167 generation (2019-onwards) and uses a different engine family from the X166-generation diesels that preceded it, so a direct swap from an older GLS diesel is unlikely to be straightforward. Your engine code (visible on the V5 or from a VIN check) is the essential reference — supply this to the breaker, who can check the donor car's code against yours before quoting. Never assume fitment across a generation boundary without that confirmation from the breaker.

The GLS, GLE (X166/X167), and ML (W166) do share engine families across certain model years, which means timing chain components can sometimes be common between them — this is worth raising with your breaker, as it can open up more donor vehicles and potentially better-priced parts. However, whether a specific chain, tensioner, or guide from a GLE or ML matches your exact GLS engine code is something the breaker must confirm against both registration numbers rather than something you should assume. Supplying your engine code and letting the breaker cross-reference it is the only reliable route here.