Introduced in 2016, the OM654 Diesel engine shocked the diesel loving Mercedes community by replacing not only replacing the previous 4-cylinder OM651 engine, but also the stronger 6-cylinder OM642 engine.
Featured image:
Thilo Parg
(https://commons.wikimedia.org/wiki/File:Mercedes-Benz_OM_654_BR_213.jpg)
https://creativecommons.org/licenses/by-sa/4.0/legalcodeMany Mercedes Diesel owners love their 6-cylinder engines, so the news of a 4-cylinder replacement was not well-received. However, the OM654 engine has proven to be nothing short of amazing. Initial reviews confirmed that this smaller diesel delivers the same power as its less fuel-efficient predecessors.
Here’s how much power you can expect from the OM654 engine and all the variants that are available.
Basic Mercedes OM654 Engine Specifications
The OM654 engine features 4-cylinder and 4 valves per cylinder. Engine internals are encased in an aluminium engine block and an under an aluminium alloy cylinder head. By using an improved simplex timing chain, Mercedes made sure that the well known timing chain issues of the OM651 engine will no longer be a concern. Depending on the variant, this engine features either a twin-turbo or a single twin-scroll turbo configuration.
The OM654 engine features 3 different displacements:
- 1.6 L (1,597 cc) (DE16)
- 2.0 L (1,950 cc) (DE20)
- 2.0 L (1,992 cc) (654 M)
And 5 different power outputs:
- The C 180d: 90 kW or 120 hp at 3,200-4,600 rpm
- The C 200d: 110 kW or 150 hp at 3,200-4,800 rpm
- The 200d: 120 kW or 160 hp at 3,800 rpm
- The 220d: 143 kW or 192 hp at 3,800 rpm
- The 300d: 195 kW or 261 hp at 4,200 rpm
Common Mercedes OM654 Engine Problems
There’s not a lot that goes wrong with these engines, however, there are three different serious and expensive to repair issues that you need to be aware off. We’ve prepared a quick summary if you happen to be in a rush.
Common OM654 engine issues include:
- Failing Rocker Bearings and Hydraulic Tappets (Damaged camshaft lobes)
- Carbon build up
- Timing chain failures
- Vacuum Controlled Coolant Pump Leak
- High Mileage Issues
We’re sure you’re thirsty for some more details, let’s get into it.
OM654 Failing Rocker Bearings and Hydraulic Tappets (Damaged camshaft lobes)
It wasn’t until 2020 that we’ve detected a massive influx of reports of rough idling, weird idling noises and sometimes even engine warning lights.
Soon after that, the problem was considered common and the component at fault were the bearings on rocker arms. Rocker arms are responsible for transferring the movement from the camshaft lobes to the valves and opening them simultaneously.
When the roller-type bearings on the rocker arms fail, they either seize up completely or become loud, which results in odd idling noises. According to the technical service bulletin from April 2020, only the rockers on the rockers on the exhaust side tend to fail, however, multiple sources have told us that it’s best to replace them all once you open up the engine.
If you ignore this issue, the camshaft lobes are going to get damaged as well, which almost doubles the cost of repairs. Inspecting all rocker arms and camshaft lobes is essential.
To resolve these issues, all affected or, better yet, all rocker arms and hydraulic tappets need to be replaced. In case of camshaft lobe damage, the entire camshaft bearing housing (approx. $500) needs to be replaced, as Mercedes does not supply the camshaft on their own.
OM654 Timing chain failures
Compared to its 4-cylinder predecessor, the OM651 diesel engine, the refreshed OM654 should be free from timing chain issues. However, we’re seeing quite a few reports of timing chain clunking noise as these engines reach the 150,000 miles (ca. 241,402 km) mark.
To make the engine run smoother, Mercedes placed the timing chain at the back of the engine, on the transmission side. While that is a smart move in terms of ride quality and engine vibration, it makes things much more complicated and costly when it’s time to replace the timing chain.
To make sure the timing chain doesn’t stretch prematurely, avoid putting excessive pressure on the engine before it heats up and avoid short trips. Remember, diesels are meant to be driven mainly on long journey.
ON654 Vacuum Controlled Coolant Pump Leak
According to an early 2022 urgent factory recall, Mercedes recalled almost a million of C-Class, CLS, E-Class, G-Class, GLC, GLE, GLS and S-Class vehicles due to a problem with the vacuum controlled coolant pump.
Both the OM654 and the OM656 diesel engines were affected. The vacuum coolant pump may not be sealed securely between the coolant and vacuum circuits. This could cause the coolant to leak into the vacuum circuit, resulting in an electrochemical reaction that increases the risk of fire.
If you own an OM654 powered Mercedes, make sure you check if your car is affected. We recommend you do the following if you’re in the market for a car with this engine.
Carbon build up
We feel like a broken radio, but let’s repeat something of great importance again; if you plan on using your diesel for short city commuting and occasional road trips, a diesel powered Mercedes is just not for you.
Short trips with diesel engines, including the OM654, lead to carbon build-up, oil dilution and blocked DPF filters. These cars are meant to be driven far and wide, and they’ll last longer if you use them for their intended purpose.
High Mileage Issues
Consider this section not as a hit on the OM654, but a piece of advice. A lot of these engines cover a big number of miles shortly after being purchased. So even if you’re buying a 3-year-old E-Class with 120,000 miles (ca. 193,121 km) or more, make sure you inspect the water pump, the thermostat, the condition of the radiators, coolant hoses and the entire engine for any signs of oil leaks.
Which Cars Have the OM654 Diesel Engine?
The OM654 Diesel Mercedes engine is featured in the following vehicles:
- W177 Mercedes A-Class 200d or 220d
- W247 Mercedes B-Class 200d or 220d
- C118 Mercedes CLA 200d or 220d
- C257 Mercedes CLS 220d or 300d
- W205 Mercedes C-Class 220d or 300d and 300de
- W213 Mercedes E-Class 220d or 300d and 300de
- H247 Mercedes GLA 200d or 220d
- X247 Mercedes GLB 200d or 220d
- X253 Mercedes GLC 200d or 220d and 300d/300de
- W167 Mercedes GLE 300d or 350de
- W206 Mercedes C-class 200d or 220d and 300d
- 2019 Mercedes Sprinter 3rd Generation (907/910) VS30
Conclusion
If it wasn’t for the annoying rocker bearing failures, we’d have no problems listing the OM654 diesel engine as one of the best modern diesels of the past 10 years. Don’t get us wrong, this is still a fantastic engine, especially for those that know how to use a diesel engine.
If you’re in the market for a used OM654 equipped Mercedes, you should pay most of your attention to the service history, the unusual idling sound of problematic rocker arms and the timing chain rattle which is best observed in the first few seconds of a cold start up. Good luck!
P.S.: If you want to learn more about Mercedes engine problems, consult our ultimate guide to Mercedes engine problems!
FAQ
Which engine is better, the OM654 vs OM651?
Based on our experience, we’d have to say that both engines are equally reliable. While we hate to leave you hanging without having a definitive winner, it’s the reality of things. The OM651 engine is a remarkable diesel engine that does carry some drawbacks like the timing chain issues and the NOX sensor failure. But the same can be said about the OM654 diesel engine. While it does experience fewer issues with the timing chain, the OM654 experiences more problems with the before mentioned rocker arms and hydraulic tappets.
Is the OM654 engine reliable?
Yes, with regular maintenance and care, the OM654 is considered to be a reliable engine. Expect some issues once you hit higher mileages, but other than that, the OM654 is a fairly reliable engine. The biggest concern with this engine are the failing rocker arm bearings.
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