Are you interested in purchasing a BMW with the S55 engine and want to learn more about the BMW S55 engine problems? If this is the case, you will find this article quite useful.
Doing good and thorough research on a certain engine is the way to go if you want to avoid some serious and expensive problems that can occur. And that’s why we are here to help you out.
First, we are going to learn the basics of the BMW S55 engine and learn more about the specs. Then, we will cover the common BMW S55 engine problems. After that, we will cover the applications and the models that include this engine and lastly, we will answer some frequently asked questions.
Basic BMW S55 Engine Specs
Now let’s learn more about the engine specs that are associated with the S55. Engine specs are really important when making a decision on an engine and whether this engine is a good idea to buy.
This S55 is an inline-6 engine based on the N55 engine. The N55 is basically the regular low-horsepower version. While the S55 is the high-performance version used in the M-models made by BMW.
Nevertheless, the S55 is a 3.0L inline-6 engine with an aluminum block and aluminum head, it implements a twin-turbo setup, which means that the engine is boosted.
The differences from the N55 include the closed-deck engine block, lightweight crankshaft, performance crankshaft bearings, high-strength pistons and rods, twin fuel pumps, and twin turbos.
This engine comes in a variety of configurations. These are the following:
- 205 kW version rated at 275 hp
- 302 kW version rated at 405 hp
- 317 kW version rated at 425 hp
- 331 kW version rated at 444 hp
- 338 kW version rated at 453 hp
- 368 kW version rated at 495 hp
As you can see, there are many versions of this engine, this tells a lot about its endurance. BMW plays with the size of turbochargers and the amount of boost to squeeze the power they want depending on the application.
Common BMW S55 Engine Problems
Now let’s learn more about what are the most common problems with this engine. First, we are going to briefly note the problems, then we are going to further elaborate on them.
Common BMW S55 Engine problems include:
- Valve Cover & Valve Cover Gasket Leaks
- Oil Pan Gasket Leaks
- Oil Filter Housing Leaks
- Crank Hub Problems
- Cooling Problems
- Water Pump & Thermostat Failure
- Engine Coolant Temperature Sensor Failure
- High-Pressure Fuel Pump Failure
Now that we listed the common problems with this engine, let’s further elaborate on them in detail.
Oil Leaks Coming From Different Parts Of The Engine
The biggest problem with this engine are probably the oil leaks that often come from different parts of the engine.
The most common place for these engines to leak are the valve covers and the valve cover gaskets. Valve covers leak because sometimes they are torqued to the wrong spec and this could cause the valve cover to crack. Even though these are hairline cracks, they can cause loss of engine oil.
The valve cover gaskets can also leak. So, if you notice some grease spots around the cylinder head, it is important to react quickly because these leaks have to be tackled.
Another very common leak is the oil filter housing. The oil filter housing can leak oil. This problem is very common on a lot of BMW engines and the S55 is no exception to this.
And the last leak that you should be worried about is the oil pan gasket leak. Oil pan gasket leaks can make the car lose a ton of oil. The solution to this is replacing the oil pan gasket with a new one and resealing the oil pan.
Overall, these problems are no big deal. You can sort them out for a few hundred dollars.
Spun Crank Hub Problems
Another very common problem with this engine is the situation with the spun crank hub. This is a big pain for this engine. Even though some BMW fans are not regarding this as a problem, it actually is a problem.
The crank pulley is basically flat, which is a completely bad idea. Under heavy stress, the bolt that keeps the hub together (since this hub is made out of three different pieces) will start to lose the timing. And whenever there is enough play, the crank hub will spin.
With the crank hub being spun, you will end up with an engine that is damaged on the inside. The pistons and valves will collide with each other. In this case, you will have to either rebuild or replace the engine.
Luckily, there are companies that make aftermarket hubs that are preventing this action and with this hub, you will drive carefree. A kit for this is about $500 and with labor, you can expect to pay up to $1,000. If you want to bulletproof your engine, this is the way to go. More about the process you can check in the video.
Water Pump & Thermostat Failure
The next problem on our list is the water pump and thermostat failure. This problem is fairly common on BMW engines. And the S55 is no exception.
This model is equipped with an electric water pump, which honestly, isn’t the best design. Mainly because these water pumps tend to fail more often compared to the classic mechanical water pumps.
And BMW engines are really plagued with these issues, including the N55 engine and S55 engine. They are basically the same engine, except for the fact that the S55 is beefed up in some areas in order to make it more bulletproof when it comes to performance gains.
Engine Coolant Temperature Sensor Failure
Another very common problem with this engine is the coolant temperature sensor. So, what is this ECT sensor all about?
Well, this sensor plays a big role when it comes to starting up the engine. This sensor gives the computer some crucial information about the temperature of the coolant.
So, if the coolant is cold, on startup, the engine would run a bit richer compared to a warm engine. Which is essential if you want to have the proper ability to start the engine.
This coolant temperature sensor also tells the radiator fan when to kick in. And what can happen is that this sensor can fail and cause the engine to run very rich, constantly run the fan or not turn the fan at all.
High-Pressure Fuel Pump Failure
And the last common problem with the S55 engine is the fuel pump failure. This engine implements direct injection. For this purpose, the engine needs something known as a high-pressure fuel pump (HPFP).
And along with the water pump, this is another very common failure point for a lot of newer BMW engines. These pumps fail very frequently. And if you have one of the earlier versions of the S55 engine, you will highly likely have to replace this pump. And these pumps are not the cheapest parts out there, unfortunately.
Which Models Include The S55 Engine?
Now let’s take a look at which models include the S55 engine. We will go through the versions, starting with the least powerful to the most powerful model.
205 kW (275hp) Model
- 2020 – Present BMW F87 M2 CS
302 kW (405hp) Model
- 2019 – 2021 BMW F87 M2 Competition
317 kW (425hp) Model
- 2014 – 2018 BMW F80 M3
- 2014 – 2020 BMW F82/F83 M4
331 kW (444hp) Model
- 2016 – 2018 BMW F80 M3 Competition
- 2016 – 2020 BMW F82/F83 M4 Competition
- 2020 – 2021 BMW F87 M2 CS
338 kW (453hp) Model
- 2018 BMW F80 M3 CS
- 2017 – 2020 F82 M4 CS
368 kW (493hp) Model
- 2015 – 2016 BMW F82 M4 GTS
- 2017 F82 M4 DTM Champion Edition
Conclusion
Now that we covered the specs and the BMW S55 engine problems, let’s sum up our conclusions. The S55 engine is a really reliable engine that can be pushed up to 600 hp with no major problems.
The core of the engine is pretty much bulletproof. We can easily call this inline-6 the modern 2JZ. There is no competition to BMW in this segment, especially with this inline-6 engine that can be pushed to such great lengths.
Although, the problem with the spun crank hub should worry you. If you want to make this engine completely bulletproof, you will have to upgrade the stock part with an aftermarket component. Besides that, everything is good with this engine except for some minor problems.
FAQs
What Problems Does The S55 Engine Have?
This engine’s main problem is the situation with the crank hub. If the hub is spun, there will be internal engine damage and the car will stall. Other problems include oil leaks from the valve cover, oil pan, and oil filter housing. There could also be failures of the secondary high-pressure fuel pump and water pump failures.
Is The S55 Engine Reliable?
In general, this engine is really reliable, if not the most reliable high-performance engine that is currently in production. The engine can be pushed up to 600 hp with no major issues, in other words, it can handle a lot of power pretty reliably.
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