BMW 3 series (F30) 2011-2019

Petrol engines

This BMW was available with many different petrol engines, but the simpler naturally aspirated port injection engines are gone forever. So all these engines are equipped with a turbocharger, with direct injection and with the Vanos variable valve timing system. Because of these things they are not only pretty complex, but they also have numerous potential failure points.

In the PRE-facelift cars you can find the N series engines and in the facelifted cars you can find the newer B series units.

N13 (316i, 320i EfficientDynamics)

The N13 is the weakest and maybe even the worst engine in this car. HERE you can check out all the issues it can have, so now just in short:

This engine can have problems with the:

• worn timing chain
• excessive oil consumption
• faulty vanos solenoids
• many coolant leaks
• many oil leaks
• cracked turbo intake hose
• a broken oil dipstick

Most of these issues can occur before 150 000 km.

N20, N26 (320i, 328i)

The N20 4 cylinder is maybe the most common and most known engine in these cars. By the way, there is also a N26 version of this engine which was produced for the US market only. But don’t be confused, it’s basically the same as the N20 so it can have the same problems.

OIL PUMP CHAIN + TIMING CHAIN

The biggest issue of these engines is related to the timing chain. Except the regular timing chain there is also a separate chain and tensioner for the oil pump. The problem is, that in cars made to 2013 they fitted a weak oil pump chain – which in a lot of cases gets worn and loose before 150 000 km and sometimes even before 100 000 km. If it fails you lose oil pressure and you end up with a seized destroyed engine, so definitely listen for a specific whining noise form the engine – which is an early symptom of a worn oil pump chain. However it is possible that the worn oil pump chain is not gonna develop any noise – like on the picture below. (on picture: worn oil pump chain at 116 000 km – in this case there was no noise)

That’s why it’s a good idea to replace the oil pump chain at 100 000km. Of course, if you are lucky then it can last even 150 000 km but after this it really is just waiting for the inevitable end. The price for replacing the oil pump chain and timing chain is around… Even though the timing chain is usually still fine at 100 000 km it’s still worth to replace it as well because the timing chain itself is not gonna last forever either!

While replacing the oil pump chain it’s also worth to replace the timing chain at the same time even though the timing chain is usually still fine at 100 000 km.

From around mid 2013 they updated the oil pump chain, but to simplify the things: In engines made from 2014 there is an updated oil pump chain fitted which can easily last even 200 000 km.

YES THERE IS ALSO THAT DAMN TIMING CHAIN

To top of that the timing chain itself is not gonna last forever either. Mainly the engines made to 2014 are gonna have more or less worn timing chain mechanism at 150 000 km or sometimes even before this mileage point. The plastic chain guides will crack and get worn as well. 

OTHER ISSUES

• electric coolant pump which can easily fail before 200 000 km
• the plastic charge pipe on the side of the intake can crack and get loose
• Vanos system related issues can easily occur too – mainly the vanos adjustment sprockets can fail + the valvetronic actuator mounted in the middle of the cylinder head can sometimes fail too

N20 replacing vanos adjusters quick video

Problems with the Vanos system components are ineviteable, symptoms: uneven engine idle, loss of power/limp mode, check engine light/drivetrain malf. with vanos related fault codes

After this there are the oil and coolant leaks… There is no time to look at them more closely, but I will mention at least the infamous plastic coolant flange bolted to the front of the engine block. It will sooner or later crack and leak coolant so it’s a good idea to replace it preventively.

If you are thinking between the 320i or the 328i, then you should buy rather the 328i, even though both of these versions have the same N20 engine, the 328i has not only more power but also a bit stronger/reinforced pistons.

N55 (335i)

The 6 cylinder N55 is essentially not a bad engine but except the oil pump chain it can have similar issues and leaks as the N20 so:

• this N55 also has an electric coolant pump which can fail before 200 000 km
• the plastic charge pipe on the side of the intake can sometimes crack and get loose the same way as on the N20
• Vanos system related issues which can easily occur too – specifically the vanos adjustment sprockets can fail, the 2 VANOS solenoids located on the front of the engine can fail or get clogged up and occasionally the valvetronic actuator mounted in the middle of the cylinder head fails too 

Last but not least, there are the inevitable oil and coolant leaks… There is no time to look at them more closely, but I will mention at least the long plastic coolant pipe which goes from the coolant tank. It will break sooner or later causing a coolant leak, so it’s a good idea to replace it preventively – pipe number: 17128570061

And as the N20, this N55 also has a plastic coolant flange bolted to the front of the engine block. It will sooner or later crack and leak coolant, so you should replace this part preventively as well.

N55 video about replacing mickey mouse flange and plastic pipe from tank

---

N series engines generic issues

Yes, there are also the generic issues which can occur to all N series engines, so:

1. Ignition coils and spark plugs

Faulty ignition coils and spark plugs are gonna cause misfires, but you already know this, hopefully… It’s good to replace the spark plugs every 40 000-60 000 km.

2. PCV

All these engines have a pcv membrane mounted into the valve cover. The membrane will crack sooner or later causing various symptoms like: misfires=uneven fluctuating idle/shaking mainly after cold start, whistling noise from engine, eventually oil consumption. The PCV membrane is part of the valve cover in all these engines, but it is possible to buy an aftermarket membrane and replace it separately. However, be ready to replace the whole valve cover anyway since the valve cover has additional channels with additional small valves and membranes which can fail/clog up too-which means that in plenty of cases replacing only the pcv membrane itself is not gonna fix the problem.

3. Classic DI problems

Since all these engines are equipped with direct injection you should expect faulty injectors, carbon build up on the valves and occasionally a faulty HPFP.

Injectors: it’s good to check/test/clean or replace them at around 200 000 km (in countries with bad quality fuel you should do this every 100 000 km)

clogged/faulty injectors are gonna have bad spray pattern which in the worst case can damage the pistons over time, symptoms of bad injectors: random misfires-slightly fluctuating idle/slight vibration at idle, jerking, not good engine start, higher fuel consumption, fuel pressure drop in fuel rail + they can let some amount of fuel into the oil too

Carbon build up: check and eventually clean the intake valves from carbon every 100 000 – 120 000 km.

Faulty high pressure fuel pump: the HPFP can fail too causing various symptoms like: issues with starting the engine, mixture too rich fault code can appear, rough idle/misfires, drivetrain malfunction message, limp mode + it can let excessive amount of fuel into the oil = so if you will have a faulty hpfp then replace the oil with it at the same time.

4. Turbocharger

The turbocharger itself can of course fail, but usually not prematurely. However, there are a couple of turbo related issues which can occur prematurely like the wastegate rattle, electronic wastegate actuator failures or the more famous failure of the turbo diverter valve.

5. Rod bearing failure (owning a horse suddenly looks like a good idea)

As an icing on the cake lets finish this list with the rod bearings. On the N55 and on the N20/N26 engines, rod bearing failures or simply worn rod bearings can occur. Mostly after 200 000 km, but sometimes even before this milage point. If you don’t catch this early or if they fail suddenly then you end up with a seriously damaged engine. So to minimize this issue you should change the engine oil every 8 000 km and you should also change the oil pump solenoid valve every 100 000 km. 

To top of that you should also consider replacing the rod bearings preventively at 150 000 – 200 000 km.

---

B38 (318i)

The B38 is a small 1.5 l 3 cylinder turbocharged unit. It’s not the worst engine in the world but I would rather avoid it.

Exhaust manifold/turbo housing crack

The most interesting issue of this engine is related to the turbocharger. Specifically, the turbo housing can crack somewhere on the inside even before 100 000 km, causing a coolant leak into the exhaust. Symptoms: coolant loss, white smoke from the exhaust, coolant smell from exhaust or engine compartment, sometimes visible coolant leak externally from the turbo area, coolant inside the rear part of the turbo-visible if you remove the catalytic converter.

Timing chain

After this it’s good to know that there are numerous cases of prematurely worn timing chains in these engines before 150 000 km like in this case but rarely even before 100 000 km like in this case.

On the other side I have to add, that in cars with regular oil changes and in cars which are used mainly for longer distances the chain can last more than 200 000 km as well. 

Inevitable oil and mainly coolant leaks:

• the plastic oil filter housing mounted on the side of the engine can easily crack and let all the coolant out.
• the water pump can leak coolant
• the sealing surface of the water pump bracket to the engine block can fail and cause a minor coolant leak
• the plastic coolant flange connected to the side of the engine block will eventually leak coolant as well, either because of the o ring on it or because it simply cracks
• the coolant tank can slightly crack
• the valve cover gasket will sooner or later leak oil
• check for oil leaks under the front part of the engine since the front plastic crankshaft cover will sooner or later leak

B48/B46 (320i, 330i)

The B48 and B46 4 cylinder engines don’t have many specific problems yet, except the coolant leaks, which are pretty common, so:

• the plastic coolant pipe which goes from the coolant tank to the cylinder head often cracks and leaks even before 100 000 km. 
• the plastic oil filter housing mounted on the side of the engine can more often crack and let all the coolant out
• the water pump can leak coolant
• the sealing surface of the water pump bracket to the engine block can fail and cause a minor coolant leak
• the plastic coolant flange connected to the side of the engine block will eventually leak coolant as well, either because of the o-ring on it or because it simply cracks
• if you notice slowly disappearing coolant from the main tank, then that can be sometimes caused by the coolant tank cap
• the valve cover gasket will sooner or later leak oil too, but that’s nothing special

B58 (340i)

The last engine on the list is the famous B58 6 cylinder which has very similar problems as the B48. So, except the coolant tank plastic pipe it can have the same specific leaks as the 4 cylinder:

• the plastic oil filter housing mounted on the side of the engine can more often crack and let all the coolant out
• the water pump can leak coolant
• the sealing surface of the water pump bracket to the engine block can fail and cause a minor coolant leak
• the plastic coolant flange connected to the side of the engine block will eventually leak coolant as well, either because of the o ring on it or because it simply cracks – part number: 11118619408
• if you notice slowly disappearing coolant from the main tank, then that can be sometimes caused by the coolant tank cap
• the valve cover gasket will sooner or later leak oil too, but that’s nothing special

B series engines generic issues

Now let’s check out the other problems related to all these B series units:

1. Fuel tank valve

All these engines are equipped with a fuel tank vent valve which is located on the top of the engine. This part can fail more often causing mainly fluctuating revs at idle or other symptoms.

2. Vanos

All these B series engines have an innovated Vanos system. Even though it is innovated you still have to expect problems mainly with the round vanos solenoids on the back side of the engines. These solenoids can often fail even before 100 000 km causing various symptoms including a strange knocking or humming/grinding noise from engine.

video about vanos solenoid problems

Additionally, the small vanos central valves can get worn causing various symptoms like vanos related fault codes stored, limp mode/loss of power. To top of that, its actually good to replace these small valves preventively, since they can contribute to the destruction of the adjustment sprockets which are more expensive to replace.

3. Cracked pistons (rare)

It can seem strange but there are numerous cases of cracked pistons in all these B series engines even before 150 000 km. In many cases the piston cracks only slightly keeping the cylinder wall intact and keeping the repair bill not that high. But sometimes the piston cracks spectacularly damaging the cylinder wall and magically filling up the oil pan with a big amount of metallic nuggets. However before you start to panic, I have to add that this is not very common. On the other side it can happen and it seems like its caused by 3 main things: injectors, a phenomenon called the LSPI and performance upgrades.

There is no time to dig deeper into these causes so let’s just check out the things you can do to minimize the chance of piston crack:

• use only premium good quality fuel eventually fuel additives
• have the injectors in good condition eventually check/test/clean or replace them preventively after 100 000 km
• always pay attention to engine misfires and fix them as soon as possible
• avoid cars with questionable performance upgrades
• change the engine oil after maximum 10 000 km, but preferably every 8 000 km
• use good engine oil
• avoid high load at low RPM conditions

cars with performance upgrades, abused cars and cars where the previous owner used cheap fuel are more prone to this

4. Regular DI problems

The second not that common issue are the classic direct injection related problems. So:

• faulty injectors
• carbon build up on the valves
• high pressure fuel pump failure

HPFP failures are actually not common at all, but injector failures can occur and carbon build up will appear on the intake valves. Usually, the carbon build up in these engines is not excessive so it’s enough to check and clean the valves only after 150 000 – 200 000 km.

On the other side, injectors can fail before 150 000 km usually causing misfires and other symptoms. BUT occasionally the injector can get stuck in the open position and overflow the cylinder with fuel and this can contribute to the already mentioned piston crack. So pay attention to the specific faulty injector signs.

faulty injector symptoms: misfires, higher fuel consumption, bad engine start – long cranking, low fuel rail pressure

good video about injector issues

ON THE NEXT PAGE: DIESEL ENGINES