Timing chain
All of the engines are equipped with a timing chain mechanism. In the older 4 cylinder N series petrol and diesel engines it can be worn at around 150 000 km and occasionally even earlier. On the 6 cyl. N57 diesel engines usually just at around 200 000 km.
On the other side, in the 6 cylinder N55 petrol engine and in the newest B series petrol and diesel engines the chain can usually last at least 200 000 km and in many cases easily even more than 250 000 km. (except in the 3 cylinder B38 petrol engine)
But either way, pay attention to worn timing chain symptoms regularly and consider replacing the chain preventively, mainly if you have one of the older N series engines.
The worn chain mechanism on the petrol engines usually just jumps, on the diesel engines on the other side it can even break/snap.
On a petrol engine when the chain jumps just slightly you will experience: check engine light, loss of power, limp mode, bad/long engine start, uneven engine running/misfires. In this case the engine is most probably not damaged, so it’s enough to replace the chain mechanism. However, if you are unlucky and the chain jumps more, then you can also end up with a damaged engine – bent valves – and in this case the repair is gonna be much more expensive.
Early symptoms of a worn timing chain: rattling / whining noises from engine constantly, or just a rattle at start up which will disappear after a while.
By the way: Not only the chain and chain tensioner can get worn, but also the plastic chain guides can crack and disintegrate over time. In this case the small plastic pieces will get into the oil pan and in the worst case clog up the oil strainer = restricting oil pressure which is obviously not good.
Transmissions
This BMW can be equipped with:
- 6 speed manual gearbox
- 8 speed regular automatic gearbox
The manual gearbox doesn’t have any extraordinary issues, so just check it properly before buying – if all the gears can be shifted easily without any bigger force and strange sounds. Additionally, there is the clutch which can be sometimes worn even before 200 000 km, so check it properly before buying as well. The clutch has to work smoothly – without vibrations or shuddering felt in the clutch pedal, without strange sounds and without slipping during harder acceleration which can be accompanied by a more or less noticeable engine power reduction (-since when the clutch slips, then the engine electronics automatically reduces the engine power, so cars with a worn clutch are gonna have slightly worse acceleration/slightly less engine power.)
on diesel engines replacing the clutch and dual mass flywheel at the dealer costs approx. 2 000 €
On the other side, if you don’t want to bother with shifting the gears manually then choose a car with the automatic gearbox which is shifting gears quickly and smoothly. However, it’s very important to check it properly before buying and change the oil in it regularly. With regular oil changes it can easily last more than 300 000 km. But without regular oil changes there is a high chance that after 200 000 km or 250 000 km the gearbox will develop issues or it will fail completely!
The gearbox has to change gears smoothly without vibrations, shuddering/jerking and fluctuating RPMs.
xDrive is good but its shit
Many of these cars are equipped with the xDrive all-wheel drive system which works very well, but it’s not very durable. Specifically, there are 2 main issues of this system:
- the xDrive transfer case can fail
- the output flange of the transfer case can wear out
1. xDrive transfer case a.k.a. What the fuck is a VTG?
VTG is a shortcut for very-tiny-gnome. This asshole gnome is living inside the transfer case. Unfortunately he is a lazy unreliable fucker who is smoking weed like an industrial chimney, so he is not gonna maintain the transfer case properly = which will result in transfer case problems. Story over.
Ok, now for real. VTG is just another name for the transfer case itself. The transfer case is a magical box which contains some gears and stuff and which is not very durable. You can expect issues with it usually just after approx. 200 000 km, but there are also numerous cases when it failed even before 150 000 km – in many cases it was replaced under warranty as well. Symptoms of a worn out or not properly working transfer case are:
- vibration/jerking/shuddering or slipping during acceleration
- eventually a metallic noise at acceleration
As I already mentioned the transfer case is not very durable, but most importantly, it’s very sensitive to many things! This means that if you don’t have one or more of the following things in order, then you can also experience faulty transfer case symptoms!
To maintain correct xDrive operation and minimize issues with it it’s important to have these things in order:
- correct wheel size on both axles
- correct tire size on both axles
- same tire model on both axles
- not too worn tires
- correct tire pressure on both axles
- enough amount and not too worn oil in the vtg
xDrive VTG sensitive to wheels and tires
The xDrive VTG is sensitive to correct wheel size and even to tire wear, so it’s important to have the same/correct circumference of all the wheels on both the axles. Incorrect wheel/tire size or more worn tires on one of the axles can cause worn out transfer case symptoms which will later contribute to premature xdrive vtg failure!
If you experience the vtg failure symptoms, then first check if you have correct wheels and tires fitted, check if the tires are not worn too much and check the tire pressure. Eventually swap the wheels for good ones with good tires. If the symptoms stop with the new wheels then you don’t have to replace or repair the vtg.
xDrive and oil
The xDrive VTG is sensitive to the oil as well, so it’s important to change the oil in the transfer case every 60 000 km to prolong the lifetime of it and to minimize issues!!
If you experience faulty transfer case symptoms and your wheels are fine and they are the correct size, then before replacing or fixing the transfer case you can try to: remove it, disassemble the main covers, properly clean it and fill it with new oil since some owners got rid of the problems after doing this cheap but labor-intensive procedure! To top of that, since the oil filling of the transfer case is only 0.7 liters, some owners went further and poured the whole 1L of transfer case fluid into the transfer case (according to their theory the factory filling is insufficient, putting the whole 1l of oil is possible thru the breather hole on the upper part of the transfer case). But if you want to drain the whole amount of transfer case oil properly then you will have to remove the transfer case and pour it out – since there is no oil drain hole just a filler plug.
Some owners also changed the oil 2 or more times without removing the transfer case and just after that they got rid of the jerking. However, it’s still better to be ready to replace the transfer case or be ready to have it rebuilt.
2. Worn transfer case output flange
The second main issue of the transfer case is related to the rear output flange which is inserted into the transfer case. The flange splines can wear out gradually and cause some early symptoms like metallic rattling noises or an occasional knocking/slipping from the gearbox area. But the splines can also wear out suddenly and in this case the car becomes undriveable. This problem can occur before 200 000 km and sometimes even before 100 000 km, so it’s a good idea to check and eventually replace the flange preventively. To top of that rarely even the splines of the transfer case shaft get worn – and this is a bigger issue since you can’t replace this main shaft that easily and cheaply like the output flange.
Except the sudden VTG output flange failure there can be also earlier symptoms of this issue like metallic rattling noises and you can also feel occasional knocking/slipping from the gearbox area.
To top of that, rarely even the splines of the transfer case shaft get worn – and this is a bigger issue since this is not an easy repair like replacing the output flange.
post about transfer case output flange issues and replacing
Differentials
Lastly you should definitely check for oil leaks from the differentials and from the transfer case. Mainly the rear differential can in many cases slightly leak even before 100 000 km. Also check for howling/whining or humming noises from the differentials, since mainly on the before facelift cars there are many cases of noisy differentials. To extend the lifetime of the differentials and to minimize the issues you should obviously change the oil in them regularly every 60 000 km. By the way, replacing the oil in the front differential is very easy since it has a fill plug and also a drain plug. But interestingly, the rear differential and also the transfer case have only filler plugs, so you have to pump out the old oil from them.
To summarize things up
- from the petrol engines it’s better to avoid the N13, the B38 and the early N20/N26 engines
- the hybrid models are not worth it either
- the diesel engines are great until they stop working or catch fire, even though the B47 is not that bad
- if you don’t want to risk additional engine damage then avoid cars with performance upgrades
- and keep in mind that it really is better to replace certain parts preventively, than to wonder why this and that suddenly failed
