Mercedes GL-Class X164 Engines — The Complete UK Guide
Every engine fitted to the first-generation GL-Class full-size SUV — from the OM642 V6 diesel to the 5.5-litre M273 V8 that defines this generation's character. Real UK replacement costs, honest reliability data, and the 2009 facelift that brought BlueTEC technology to the UK market. Backed by 880+ real UK OM642 enquiries in 2025 [MB-VERIFIED].
Explore X164 Engines
Mercedes GL-Class X164 Engine Codes — The Complete Database
Every engine fitted to the X164 full-size SUV — including the 2009 facelift that brought BlueTEC technology and revised power outputs.
Overview
Mercedes GL-Class X164 — Overview
The X164 is the first generation of the Mercedes-Benz GL-Class, introduced in 2006 as the flagship of the Mercedes SUV line.
Built on the same platform as the W164 M-Class, it offered three rows of seating and full-size luxury in a seven-passenger package. A 2009 facelift brought revised styling and the introduction of BlueTEC diesel technology to the UK market. The range spanned from the OM642 V6 diesel to the 5.5-litre M273 V8, with the OM629 V8 diesel sitting between them.
Key Facts
Platform
Mercedes-Benz W164/V251
Predecessor
— (first generation)
Successor
GL-Class X166 (2012–2015)
Sibling body styles in this generation
None (X164 is a standalone full-size SUV; shares platform with W164 M-Class and R-Class)
Market Intelligence
The OM642 V6 diesel engine family generated 880 real UK enquiries in 2025 [MB-VERIFIED], concentrated on the GL 320 CDI and GL 350 BlueTEC as these ageing full-size SUVs continue to serve family and towing duties.
Best & Worst Engines
Best Diesel Overall
OM642.822 (GL 350 CDI, 265 bhp, post-2010)
“The most powerful iteration of the OM642 V6 diesel offered in the X164 — 265 bhp and 620 Nm of torque in a 2.5-tonne SUV. Oil cooler seal failures and exhaust manifold cracks are its known weak points, but the underlying engine is robust and proven across millions of Mercedes vehicles.”
Who it's for: buyers who want maximum diesel torque without the V8's fuel bills.
Best Petrol Overall
M273.963 (GL 500 / GL 550, 5.5L V8)
“The 5.5-litre naturally aspirated V8 delivers 388 bhp and 530 Nm of torque — effortless, smooth, and the engine that defines the GL-Class experience. Thermostat failure and intake manifold actuator issues are its only real demands, but it's a proven, characterful engine.”
Who it's for: buyers who want V8 refinement and don't mind the fuel bills.
Highest Risk
OM642.940 (GL 320 CDI, pre-2009)
“The early OM642 V6 diesel is a solid engine, but oil cooler seal failure (located in the V of the engine) is a £1,000+ repair — and earlier cars (pre-2009) have a documented risk of crankshaft main bearing fatigue.”
Who it's for: buyers who accept the risks of an early V6 diesel and have service history to prove maintenance.
Most Expensive Failure
M273.963 (GL 500 / GL 550)
“The 5.5-litre V8 is a masterpiece, but it's an ageing, complex engine — thermostat failure, secondary air injection pump failure, and intake manifold actuator issues are all common, and parts are expensive. A full replacement can exceed £8,000.”
Who it's for: buyers who want the flagship V8 and have the budget to maintain it.
Best Value
OM642.820 (GL 350 BlueTEC, 211 bhp)
“The post-facelift diesel offers improved emissions technology with the same core OM642 reliability — and significantly lower fuel bills than any V8. It's the sensible choice for a 2.5-tonne SUV.”
Who it's for: buyers who want diesel economy and don't need the extra power of the 265 bhp version.
Most Overlooked
OM629.913 (GL 450 CDI, 4.0L V8 diesel)
“The 4.0-litre V8 diesel is often forgotten between the V6 diesel and the 5.5-litre petrol — but it offers 306 bhp and 700 Nm of torque, combining diesel economy with V8 refinement. It's rare, but that's exactly why it's overlooked.”
Who it's for: buyers who want V8 presence with diesel running costs.
Mercedes GL-Class X164 — Ownership Economics
The X164 rule
A £3,200–£6,000 OM642 recon against a £4,000–£12,000 X164 sits at 25–150% of the car's value — on sub-£5,000 examples, it often approaches or exceeds our 70% Mercedes-Benz threshold. The M273 V8 recon at £4,000–£8,000 against a £5,000–£15,000 GL 500 is 25–160% — viable only on well-maintained, higher-value examples. These are ageing, heavy SUVs; value the car first, because the engine can easily be worth more than the car on budget examples.
Key Takeaways
Which X164 Costs Least To Own?
GL 320 CDI (OM642) — cheapest diesel recon, best fuel economy.
Which X164 Costs Most To Own?
GL 500 (M273) — V8 parts and fuel costs.
Which X164 Is Best Value?
GL 350 BlueTEC (OM642.820) — modern diesel without the early OM642's risks.
Common Problems
X164 Engine Replacement Costs — By Engine and Condition
No Generation variance from the baseline figures — the X164 shares its platform with the W164 M-Class, and engine-bay access is consistent across the range.
Core Variants
Core Variants
Diesel Variants
Scope note: All variants listed are X164 GL-Class only (2006–2012). The X166 GL-Class (2012–2015) and X167 GLS (2015–present) are separate generations. The GL 400 CDI was produced for non-UK markets and is not covered here. Note that the GL 350 CDI (265 bhp) was introduced post-2010 as a higher-output version of the OM642.
Market Intelligence
Most Requested E90 Engines (2025)
- 1.1. OM642.940/820/822 (GL 320 CDI / GL 350 BlueTEC / GL 350 CDI) — 880 [MB-VERIFIED]
- 2.2. M273.963 (GL 500) — pattern data
- 3.3. OM629.912/913 (GL 420/450 CDI) — pattern data
Most Requested E90 Variants
- 1.1. GL 320 CDI
- 2.2. GL 350 BlueTEC
- 3.3. GL 500
Average E90 Replacement Cost
£3,200–£8,000 [MB-QUOTE]
Most Common E90 Failures
- 1.1. OM642 oil cooler seal failure
- 2.2. OM642 exhaust manifold cracking
- 3.3. M273 thermostat & intake manifold actuator failure
Mercedes GL 320 CDI X164 (OM642)
6
enquiries
Mercedes GL 500 X164 (M273)
4
enquiries
Mercedes GL 420 CDI X164 (OM629)
3
enquiries
FAQ
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UK Engine Replacement Services for X164
covering every variant from GL 320 CDI to GL 500, with supply‑only or full supply‑&‑fit available nationwide.
Find the best Mercedes GL-Class X164 engine replacement UK drivers rely on. Compare real prices from trusted specialists on EnginesMarket today — whether you need a V6 diesel for towing, a V8 diesel for refinement, or the flagship V8 petrol, we'll help you keep your full-size SUV on the road.
