TDV6 / SDV6 vs OM656: which engine is more reliable?

According to our risk index, the OM656 carries less risk than the TDV6 / SDV6: 39/100 versus 46/100 (both moderate risk). The TDV6 / SDV6 has 2 documented serious faults, the main one being «Crankshaft breakage and spinning main bearing shells»; the OM656 has 2 documented serious faults, the main one being «Leak in the vacuum-driven coolant pump (fire risk)».

Risk index

TDV6 / SDV6

Moderate risk · 2 serious faults

Risk index

OM656

Moderate risk · 2 serious faults

Lower risk

The index (0–100) weights the severity and frequency of the three most serious documented faults. How it is calculated

Reviewed on 9 October 202614 sources How we work

Is the TDV6 / SDV6 reliable?

The Land Rover and Jaguar TDV6/SDV6 diesel V6 engines, shared with Peugeot and Citroën, have a serious documented fault: crankshaft and main bearing shells on the 3.0, and the belt-driven oil pump on the 2.7. Insist on a service history and weigh up the repair cost before buying.^[1][2][3]

See the 3 of the TDV6 / SDV6 faults

Is the OM656 reliable?

The OM656 is the roughly 3.0-litre in-line six-cylinder diesel with which Mercedes-Benz replaced the OM642 V6 from 2017 in the S-Class, E-Class, CLS, GLE, GLS and G-Class (350 d, 400 d and 450 d). It has few documented faults: the known campaign is the coolant pump one of 2021-2022, and the timing chain recall that circulates belongs to the OM654. Guides warn about the AdBlue/SCR system, the EGR and, in isolated cases, the roller rocker arms, without figures.^{[4][5][6][7][8][9][10][11]}

See the 4 of the OM656 faults

Side-by-side comparison

Comparison of TDV6 / SDV6 and OM656
Item	TDV6 / SDV6	OM656
Technical data
Type	Engine	Engine
Fuel	Diesel	Diesel
Displacement	2,720 cm³	2,925 cm³
Timing	Wet belt (belt-in-oil)	Chain
Power	188–302 hp	272–367 hp
Production	2004–2018^[12]	since 2017^[4][5][13]
Reliability
Risk index (what is it?)	46Moderate risk	39Moderate risk
Documented faults	3	4
Of high or critical severity	2	2
Worst severity	Critical severity	Critical severity
Main faults	Critical severity: Crankshaft breakage and spinning main bearing shells Critical severity: Broken oil pump housing and timing belt jumping on the 2.7 Medium severity: Turbo and pneumatic actuator failure on the 3.0 TDV6/SDV6	Critical severity: Leak in the vacuum-driven coolant pump (fire risk) Medium severity: NOx sensor failure and AdBlue (SCR) system warnings Medium severity: EGR valve clogged with soot after short journeys
Most expensive documented repair	No reliable data	No reliable data
Which versions to buy
BuyRecommended versions	None	OM656 3.0 diesel with electric assistance (D 30, from 2023)^[7][8][10]
With cautionVersions to be cautious about	2.7 TDV6 (276DT/DT17, 2004-2010)^[3][14] 3.0 TDV6/SDV6 (306DT, 2009-2018)^[1][2]	OM656 2.9 diesel 350 d (OM 656 D 29 R SCR, from 2017)^[6][7][8] OM656 2.9 diesel 400 d (OM 656 D 29 SCR, from 2017)^{[6][7][8][10]}
AvoidVersions to avoid	None	None

Severity of each fault: green, low; amber, medium; red, high; dark red, critical. How we rate them

Cars that each one is fitted to

TDV6 / SDV6

See the 14 models with the TDV6 / SDV6

OM656

See the 11 models with the OM656

Other comparisons

With the TDV6 / SDV6

With the OM656

Compare other engines

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Sources

Every fact on this page links to its source. If you find an error, let us know.

Land Rover Discovery TDV6 engine failures making headlinesLandyOnline · Other source · published October 2015 · consulted 5 October 2026
Land Rover & Jaguar SDV6/TDV6 Crankshaft RepairJLR Engines · Technical documentation · consulted 5 October 2026
Land Rover 2.7 TDV6 Timing Belt Replacement GuideBudget Parts (roverparts.eu) · Technical documentation · consulted 5 October 2026
Mercedes-Benz OM656 engineWikipedia · Other source · consulted 9 October 2026
Mercedes-Benz OM 656Wikipedia (alemán) · Other source · consulted 9 October 2026 · in German
Rückruf für OM 656 und OM 654 Motoren wegen KühlmittelpumpeMBpassion · Motoring press · published 9 December 2021 · consulted 9 October 2026 · in German
Mercedes-Rückruf: Kühlmittelprobleme bei DieselautosAUTOHAUS · Motoring press · published 5 January 2022 · consulted 9 October 2026 · in German
DVSA – base de llamadas a revisiónDVSA (Reino Unido) · Other source · consulted 9 October 2026
Mercedes-Benz GLC (X253): Alle typischen Probleme & MängelGebrauchtwagenberater · Motoring press · consulted 9 October 2026 · in German
Mercedes OM656 Diesel: Häufige Probleme, Ursachen & Tipps zur Vermeidung von MotorschädenMBpassion · Motoring press · published 19 February 2026 · consulted 9 October 2026 · in German
Mercedes-Benz OM656 Engine Guide: Reliability, Common Problems & Tuning PotentialEuro Premium Parts · Technical documentation · consulted 9 October 2026
Ford AJD-V6/PSA DT17 engineWikipedia · Other source · consulted 5 October 2026
Mercedes-Benz S-Class (W222)Wikipedia · Other source · consulted 9 October 2026
TdV6 Timing BeltLes Richmond Automotive (lrautomotive.com.au) · Technical documentation · consulted 5 October 2026