The BMW M52 engine debuted in 1994 in the E36 3-series and continued in production until 2000. The predecessor was the M50 engine and it was succeeded by the M54 in 2000.
3 version of the M52 were manufactured: a 2.0L (M52B20), 2.5L (M52B25), and 2.8L (M52B28). In 1998 the three versions all received a “technical update” which added a dual-vanos system, a DISA intake manifold, and electronic throttle control, to name a few. The technical update engines can be recognized by the added “TU” on the engine codes.
The M52 was primarily used in the E36 3-series and E39 5-series. However, it was also used in a handful of late 90’s E46’s and in a few other cars such as the E38 7-series, and E36/E37 Z3.
Check out our M54 common engine problems post too!
BMW M52 Reliability
Before digging into specific engine problems, lets talk overall reliability. The newest M52 is at least 20 years old now, and the oldest are considered classics. With that being said, if you are planning on buying one of these, it is likely high mileage. Which means you should factor in some maintenance and repairs for general wear and tear items.
Overall, the internals of the engine are bulletproof. You should easily surpass the 200k mile mark without any valves, chain, rods, crank, or seal issues. While the engine and its internals can be beat to death, the supporting engine systems are what are likely to give you problems. The cooling system, including water pump, radiator, expansion tank, etc. are all prone to failure and will likely fail at least once by the time you get to 200k miles.
The transmissions on these cars are also very strong and reliable, although you might start to experience some issues above the 150k mark. Maintenance is key. BMW transmission oil is supposed to be “lifetime” but I recommend replacing this every 100k miles, especially on a vehicle this age.
The stock sport suspension is fantastic for a car of this age, but you’ll probably need to replace some struts and shocks every ~100k miles. Front brakes and rotors should be changed every 30k miles and the rears should be changed every 60k miles.
All in all, these are great engines, but you’re going to spend your fair share of money in the repair and maintenance category – which can be expected for any car of this age.
The 5 Most Common BMW M52 Engine Problems
- Radiator & expansion tank leaks
- Water pump failure
- Rough idle from idle control valve
- Valve cover cracks & oil leak
- Dual-vanos failure
1. M52 Radiator and Expansion Tank Leaks
The cooling system on the M52 seems to be the Achilles heel of these cars. The majority of radiator support parts are made of plastic on these cars, which means they are very prone to cracking and leaking. Radiator leaks are common and usually stem from the top radiator pipe and the thermostat housing.
Additionally, the coolant expansion tank is also made of plastic and is prone to cracking and leaking.
M52 Coolant Leak Symptoms
- Coolant fluid on your garage floor
- Frequent engine overheating
- Low coolant light on the dash
If you are experiencing common overheating, you either have a failed/cracked radiator, or a leak somewhere in the cooling system. If your engine is overheating, pull over and have it towed to a shop! Continuing to drive on an overheated engine can result in warping the head or internals, requiring a full engine replacement.
2. M52 Water Pump Failure
The M52 water pump uses a plastic impeller, which is the piece that flows the coolant through the engine. The plastic impeller commonly breaks from normal wear and tear and can cause you water pump to stop functioning. The water pump typically goes out every 80k-100k miles.
M52 Water Pump Failure Symptoms
- Engine overheating
- Cooling fan running non-stop
- “Limp mode” or reduced power, acceleration, and performance
Replacement options: with the plastic impeller being the main failure point in these, we recommend upgrading to something with a metal or stainless steel impeller. The water pumps with metal impellers won’t last as long as those with stainless steel, but they are also 5x cheaper. If you want to replace this once and be done with it, get the high-flow pump with stainless impeller. If you want to save a few bucks but maybe have to replace this more than once, go the cheaper route.
M52 High-Flow Water Pump w/Stainless Impeller – ~$215 and lifetime warranty
M52 Water Pump w/Metal Impeller – ~$45 but 24 month / 24k mile warranty
3. Idle Control Valve Failure
The idle control valve on the M52 picks up dust and dirt over time which can result in it no longer functioning properly. This valve is self-explanatory, it controls car idle by regulating air to fuel ratios at idle. A bad valve will result in irregular and rough idling. Some other similar symptoms are hunting, stalling, and sputtering.
The repair here is rather simple. All you need to do is remove your idle control valve, which is connected to the intake. I say simple, but the ICV is sort of a pain to access and remove.
DIY cleaning / replacement guide: https://www.bimmerforums.com/forum/showthread.php?322651-DIY-Cleaning-Replacing-Idle-Control-Valve-(ICV)
Replacement Part: M52 Idle Control Valve – ~$200 with lifetime warranty
4. M52 Valve Cover Cracks & Oil Leaks
If you’ve owned a BMW before, you probably aren’t new to oil leaks. BMW valve covers are infamously made of plastic (they are on most other cars too). Because they are made of plastic in a high heat area, they are prone to cracking over time from sustained heat. Even the smallest crack can result in an oil leak. Additionally, the valve cover gaskets frequently cause oil leaks from normal wear and tear, as they are made of rubber.
M52 Valve Cover Leak Symptoms
- Oil around the engine cover
- Oil dripping down the side of the engine
- Stains from oil on your garage floor
- Excess oil in the spark plug holes
First step in repairing this is determining whether it is a cracked cover, or just an old gasket. Hopefully just the gasket. If you are experiencing a leak, pull off the cover and inspect it for any cracks or irregularities. If all looks good, you can start off by just replacing the gasket, which is pretty inexpensive. Also make sure to check your spark plugs holes too. Oil in the spark plug holes can foul the plugs and cause them to go bad. If this happens, you also notice poor idling and performance conditions.
5. M52 Vanos Failure
The M52 has a dual-vanos system, which controls the timing of both the exhaust and intake camshafts. Vanos systems tend to be faulty in today’s BMW’s too, but are especially common in the early engines which were first to use the systems.
M52 Vanos Failure Symptoms
- Rough idling
- Loss of driveability, horsepower, and torque
- Issues with cold starts
- P1520 engine code: camshaft position actuator faulty
- P1523 engine code: camshaft position actuator tight or jammed
- P1397 engine code: camshaft position sensor
Replacement is less simple in these older vehicles then today’s newer ones. Your two options are either to replace the full unit, or rebuild the actuators. Removing the unit requires carious special tools and complex removal processes, unfortunately.
I’d recommend checking out DrVanos if you are having issues with your vanos unit.
As previously mentioned, these are great engines and the internals themselves are going to last you a lifetime. But as the car ages and gets old, maintenace becomes critical, and supporting engine parts are naturally going to fail from wear and tear. If you own one of these, I’m sure you’re aware. If you’re looking at buying one, just plan to do a lot of regular maintenance and keep some money aside in the bank for costly repairs.