8 Common BMW S50 Engine Problems (E36 M3, Z3M)

Are you planning to purchase a BMW E36 M3 and you look to learn more about the possible BMW S50 engine problems? Well, if that is the case, then you are at the right place because, in this article, there will be a lot to cover.

Researching is something that you want to avoid possible problems in the long run. Especially second hand vehicles can be susceptible to problems. Mainly because you don’t buy them from the showroom floor but from the second, third, or even fourth owner. So, research is key and we are here to help you out.

First, we are going to cover the basic S50 engine specs, the common BMW S50 engine problems, as well as the applications of this engine. Lastly, we will cover some frequently asked questions. So, let’s dive in.

Basic BMW S50 Engine Specs

The S50 engine is the high-performance version of the M50 engine. This means that the S50 was only included in some of the high-performance M-models that BMW introduced to the market between 1992 and 2000 when this engine was produced.

The S50 replaced the good old S14. The S14 was the inline-4 engine that became really successful with the E30 M3.

But for the newer models, BMW decided to add two more cylinders in order to deliver more power to the wheels. Mainly because since the early 90s cars became much heavier and more power was essential to make the new BMW E36 M3 competitive.

This new S50 engine as we noted is based on the M50. So, it carries the same inline-6 layout but with a slightly different bore and stroke. What is worth noting is that there were three main variations of the S50 and these are the following.

  • S50B30

This is the original version of the S50 engine that was introduced globally, except for the US market. This engine is 3.0L in displacement and was rated at 210 kW (282hp), this engine redlines at 7,200 rpm.

  • S50B30US

This was the S50 engine for the US market. This engine is closer to the M50 than the non-US model. It keeps the same engine block but uses different camshafts, pistons, connecting rods, and a different crankshaft. This engine produces 179 kW (240hp). Starting from 1996, this engine was replaced by the S52.

  • S50B32

This version replaced the S50B30, except for US and Canada. This was a 3.2L engine. This means that the bore and stroke were increased compared to the standard version. This engine implements double VANOS and also a secondary oil pickup. This engine was rated at 236 kW (321hp) and has a redline of 7,600 rpm.

Common BMW S50 Engine Problems

Now let’s briefly cover the common BMW S50 engine and see what troubles this engine the most.

  • VANOS Failures
  • Spark Plugs & Ignition Coil Failures
  • Injector Failures
  • Idle Air Control Valve Failures
  • Fuel Pump Failures
  • Cooling System Problems
  • Secondary Air Pump Failures
  • Vacuum Leaks

Now that we briefly covered the BMW S50 engine problems, let’s move on and further elaborate on these issues and learn more about how they appear and the symptoms associated with them.

VANOS Failures

This engine started to implement a new technology known as VANOS. In other words, this is BMW’s name for variable valve timing.

Variable valve timing simply helps adjust the position of the camshaft. It can either advance or retard the position of the camshaft in order to maximize performance and improve fuel economy.

And this technology did not come with issues. These issues still trouble a lot of BMW models even today.

Namely, on the S50 the VANOS pump can fail and trigger a check engine light and loss of power. Other symptoms are also present.

All this is because of the seals that start to leak. A complete rebuild of this component will be needed if you want to regain the functionality of the VANOS.

In addition to this, the solenoids and their wires can also suffer. The solenoids are the electrical actuators for this system that are also notorious for failing.

Spark Plugs & Ignition Coil Failures

The next common problem on our list is the issue with the ignition components. Both spark plugs and coils tend not to last on this engine.

Mainly because this is a high-performance engine. Every high-performance engine goes through these components much more frequently compared to a standard engine.

Luckily, replacing these components is not expensive. When it comes to the coils, in some cases, you will only have to replace the rubber boots that often crack and cause a ton of problems on these old engines.

Injector Failures

Injector problems with this engine are also very common. With age, they get very dirty, and cleaning them is not an option.

The only way around this would be to replace them if you don’t want to have problems down the line.

These components also are not very expensive after all. You can find a good set of aftermarket injectors for a really good deal. Also, upgrading them is an option if you want to get more performance from this engine.

Idle Air Control Valve Failures

This engine, just like many engines from the 90s era that were built before the implementation of fully electronic throttle bodies used something known as an idle air control valve or IAC.

This idle air control valve had the purpose of keeping the engine idling at normal RPM by allowing some air to enter the intake.

And what can happen is that this IAC valve can get stuck open or closed. So, if the valve is open you will have an abnormal idle. Or if it’s closed, the engine will simply want to stall all the time. Replacing this component will sort out the problem.

Fuel Pump Failures

Fuel pump failures are also a common thing on these older BMWs. Inside the fuel tank, there is a fuel pump that pumps the gas into the fuel system.

These pumps are notorious for failing. Unfortunately, the only way around this problem would be to completely replace this pump with a new unit. These pumps can be very pricey to replace.

Cooling System Problems

Cooling system problems are also a common thing on this engine and the M50 engine. The cooling system installed on these engines is everything but reliable.

Water pump and thermostat failures are notorious. Blown head gaskets are a completely normal thing on these engines.

In addition to this, the cooling hoses, expansion tank, and radiator can also fail very frequently. If you want to have a fully reliable BMW with the S50 engine, replacing all these components is essential. If you don’t do so, the engine would overheat and it could cost you a good penny to sort it out.

Secondary Air Pump Failures

This engine uses something known as a secondary air pump. This small air pump has the task to run air into the exhaust system in order for the O2 sensor to work better and also cut the emissions on cold start.

What can happen is that the secondary air pump can fail and cause a check engine light and other issues at cold start.

Many people simply decide to delete this pump with a block-off plate. There are many of these kits available out there.

Vacuum Leaks

Vacuum leaks are very common on these engines as well. These BMW engines are running a lot of vacuum lines. There are lines for the PCV system, EVAP, and so on. Considering the age of these vehicles today, you’re in for some tedious work when replacing all these little lines.

These lines can fail and allow unmetered air to enter the engine. When this happens, you will face running issues and check engine light. The only way to properly detect and fix these problems is by running a smoke machine.

Which Models Include The BMW S50 Engine?

Now let’s take a look more at the applications where we can find this engine.


  • 1992-1995 BMW E36 M3 (Global Model)


  • 1994-1995 BMW E36 M3 (US Model)


  • 1995-1999 BMW E36 M3 (except for US and Canada)
  • 1996-2000 BMW Z3 M Coupe and M Roadster (except for US and Canada)


The S50 engine has created a true benchmark of what a BMW engine should represent. It was the first of its kind of legendary inline-6 engines that were included in the M3 model.

And overall, the engine is really good if you want to get something classic. Although, it might require some serious maintenance to bulletproof the engine for the years to come.


What Are The Common BMW S50 Engine Problems?

Common problems with this engine include VANOS issues, secondary air pump problems, spark plug and coil failures, IAC valve failures, and fuel pump failures. Also, cooling system problems are present, these include the water pump, thermostat, radiator, and expansion tank failures. The cooling system is not one of the strong points of this engine and can fail often.

Is The BMW S50 Engine Reliable?

The mechanical parts of this engine are really reliable. The problems this engine has are mostly connected to other components around the engine. Like the cooling system and ignition components. Considering the frequent failures of these components, we can say that the overall reliability is somewhat below average.

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