Before getting started I wanted to say I feel bad about calling the BMW N63 ‘hot garbage’. The N63 Twin Turbo 4.4l V8 is a wonder of modern technology, achieving things that no other engine maker was willing to attempt. The manufacturing processes that went into crafting it are exquisite. That says a lot for BMW, as they refuse to allow technical innovation to stagnate. One of the cars that this was installed in was the BMW 750li, a vehicle that approaches 5,000lbs with driver, makes almost 450hp, and still manages to get around 25mpg on the highway. That’s V12 performance out of a V8, and impressive no matter how you cut it. But alas, when you shoot for the stars you are bound to get a few failures to launch.
Breaking new ground with the BMW N63
When it came out in 2008, the future looked bright. Utilizing some interesting concepts, such as the hot-vee (exhaust exits into the turbos on top of the engine, in the valley, rather than out the bottom), BMW was taking a lot of risks doing it this way. This design, as well as the now-common high pressure direct injection system, led to some complexities that in hindsight probably should have better been left on the table. The engine bay packaging is great though, nobody can argue that.
One interesting over-complexity is the use of air-to-water intercoolers, rather than the standard style air-to-air exchanger. This is meant to save space and dramatically shorten the intercooler piping. However, because of how much heat is being generated, the air-to-water intercoolers utilize a separate coolant pump and reservoir, and THAT has its own radiator in the front of the engine. What this does effectively is kill two birds with one Tomahawk cruise missile, fired from orbit.
The N63B44O0 engine was the first N63 to ship, and went into 5-series, 6-Series, 7-Series, X5, and X6 model that have names ending with a ’50’ between 2008 and 2012. With such fresh technology, the odds of it reaching the beach was questionable. Shortly after launch, BMW owners started complaining about problems ranging from abnormal oil consumption and rough idle, all the way up to complete failures. Enough N63B44O0 engines were coming into dealers with severe engine problems that BMW launched a preemptive fix campaign to help alleviate the risk of having to replace entire BMW N63 engines under warranty.
The N63 Customer Care Package, Service Bulletin B001314
In 2012, the BMW N63 received its first major technical update, known the N63B44O1. Also referred to as the N63TU ‘Technical Update’, it used several components off the venerable N55 turbo engine. These include the fuel injectors (which utilized a different style design) and Valvetronic III variable lift intake cam system, which was omitted at the original launch. However, this was not enough to fix the ailing powerplant, and the N63 continues to be plagued by issues baked in from the original design.
In December of 2014, BMW launched a campaign called the Customer Care Package, which is widely covered across the internet. Sometimes requiring in excess of 40 hours of labor worth of work, the Customer Care Package was meant to cut off the naysayers at the pass and fix the problems before they happened, without using the dreaded R word (recall, oops I said it). It went well, with many people dropping off practically new cars and having substantial preemptive work done. Good on BMW for doing this, although many agree they pretty much had to. Here are some of the things that this covered:
Predating the N63, the BMW Efficient Dynamic system utilized regenerative braking to help the alternator to charge the battery. Because the system relied on a driving style with a lot of off-throttle coasting, in certain driving situations the battery would not be adequately charged. BMW started using AGM batteries to help with the situations of deep discharge, which was effective until the N63 showed up. With the extraordinary amount of heat in such a small space, the cooling system had to work overtime to keep temps down after the car shut off. That meant extended running of fans and electric water pumps well after the engine shut off. The size of the battery was increased, but in some cases this was still not enough. The solution was to just continuously replace batteries, sometimes as often as every oil change.
The BMW N63 is a thirsty motor, and this became apparent early on. BMW (unofficially, I can’t find the official statement to confirm this) suggests this is due to an improper break in and going too easy on the motor while brand new. Because not everyone drives their luxury land-yacht like they are in ‘The Fast and Furious: Deutsch Rennwagen fahren mit hoher Geschwindigkeit‘, the oil change interval was moved from the insane 15k miles, to 10k. An extra liter was added to the capacity of the sump to make all the way to 10k without a top-up.
Additionally, because of how hot the top of the engine is, the plastic PCV system gets an extreme workout in the heat cycling category. This causes hoses to crack and break, and seals to shrink, causing oil leaks all over the place. Typically these manifest themselves as a faint waft of oil smoke coming out from under the hood, very luxurious.
Speaking of Luxurious, the valve stem seals are another non-metal component on the top of the engine that are subjected to huge doses of turbo heat. Eventually they will start to leak, causing your high end BMW to smoke like a Dodge Monaco after a few too many years in the front yard. A friend of mine runs a shop called Swedish Performance outside Raleigh, NC, and sees these come in often. He recently did the valve seals on an N63 equipped X5, and sent a few photos of what the job was like. Looks like a good time.
Even though the injectors were changed between the first generation and the technical update, the high pressure fuel injector units are still, and always will be, a constant problem for owners with the N63 engine. These were checked and replaced under the Customer Care Package with an updated style of injector. This is why many N63 owners will notice that the dealer may have replaced all of your fuel injectors at once. The updated injectors can’t be intermixed with the outgoing style, and really, why would you want to risk it anyway? I have even read reports of broken injectors flooding cylinders with enough raw fuel to trigger a chain reaction, ultimately ending in hydro locking and complete engine failure.
Direct injection engines are susceptible to numerous issues, and the N63 is no exception. Because fuel is being blasted at high pressure directly into the combustion chamber, rather than spraying at a low pressure past the open intake valves (like standard port injection cars), there’s nothing to clean the backs of the valves off. Where port injection engines use gasoline to keep the valves free of PCV oil and sludgy carbon crud from the combustion chamber, the intake valves on direct injection cars get caked on with black buildup called coking. This will make the engine run terrible due to constricted, rough air passages. BMW’s official intake valve cleaning requires removal of the intake manifolds (on the bottom of the engine for the N63), and then a thorough media blasting with broken up walnut shells. Then the shells are vacuumed out of the chambers. Yes, walnut blasting is a thing, and will keep any direct injection car running right.
The N63’s timing system is not immune to issues either. Stretched and broken timing chains have claimed numerous engines before they could get the Customer Care Package inspection and replacement. Here’s a particularly spooky thread outlining the experience of a 750li driver that had a massive timing failure just 4000 miles after the CCP was performed, ultimately totalling around $15k in engine out service work. The owner states it was the result of a broken chain guide, rather than the commonly broken or stretched chain itself. If you plan on trying to do the timing on one of these yourself, be aware we have several of the required special tools to rent.
As part of the BMW N63 Customer Care Package, the Mass Air Flow sensor (which is the high precision hot film type MAF) as well as the vacuum pump was commonly replaced. I am not sure if these parts are updated versions currently, like the injectors, but their failure is most certainly linked to the heat of being directly adjacent to the exhaust manifolds and turbochargers. The vacuum pump is also on the list of likely replacement under the CCP. Granted, this is not all of the strife faced by owners of these latest generation of cars, which also feature problems with the drivetrain, active suspension, and other numerous systems.
All in all, the internet has no shortage of people flooding forums looking for answers as to why their BMW is running poorly, and it goes without saying that’s a horrible feeling. A cursory Google search reveals multiple class action lawsuits, but to be fair to BMW they are fixing these cars for the most part.
We’ve been noticing a steady uptick in N63 parts and special tool rentals, specifically the fuel injectors, PCV kits, and oil and coolant seals. If you are looking at buying a car with the N63 engine, be warned of these potentially critical issues associated with them.