aftermarket master once said, for us ordinary family Car, as long as we can the owner be good maintenance of engine maintenance, engine problems occur rarely, rarely reach dIsassembled overhaul the point. The reason most of the engine overhaul Is because the owners no good engine maintenance caused, such as not timely maintenance, poor use of the oil filter during maintenance and so on!
However, although we sometimes owners have been very good for engine maintenance, but there are some engine overhaul because it Is their own reasons! ThIs Is our owner Is difficult to avoid! Some time ago, a garage overhaul of the BMW inline six-cylinder engine line five, because of their own reasons to be dIsassembled engine overhaul! Overhaul reason Is difficult to avoid, people feel very sorry! To thIs end, Xiao Wu chose eight in the garage to shoot pictures of actual service to riders together and you find out the cause of thIs regrettable! (Emphasize: ThIs Is just a very special maintenance case, does not mean all)
As shown in
graph Is thIs Is a BMW five series sedan factory in 2007, has now been ten years time! It Is equipped with the unique BMW inline six-cylinder engine, ZF six-speed manual gearbox, rear-wheel drive. It was dragged back to the master Automotive, reflects the owner’s fault phenomenon: twIst the key, the engine can not be started. The aftermarket master judge after examination, thIs Is a problem inside the engine, in order to determine the specific reasons only open the engine! Left red line Is the engine, the right Is the gearbox.
FIG, the master has the Automotive engine and transmIssion to separate. Is shown in red region of the engine wiring harness, in the intake manifold BMW logo shown in the green region!
FIG indicated by an arrow, the master just opened Automotive engine valve operating chamber cover. We can see inside the engine particularly clean, the owner of engine maintenance especially good to know that BMW mileage has exceeded one hundred thousand kilometers! Aftermarket master Carefully look to see where the problem lies, the orange area, the chain has itsIt was not in a straight line up! ThIs Is how it happened?
The following figure shows the red area, the chain on the slide has an engine exhaust camshaft out of gear! Aftermarket master introduced, which Is equivalent to engine timing problem, more serious! It’s how the chain Will come off the gear it? Thus, the master Automotive lamp used to look below the engine along the chain!
shown below, Auto repair master see a problem! Aftermarket master introduced, would have been here a screw, but now the screw head has dIsappeared! ThIs means that the screw has been broken, broken screw head stuck in the top of the chain, but the owners do not know, start the engine when it took the chain off the Card!
As shown in
the arrow, Auto repair fracture in thIs master screw has been removed , and finds a screw head fracture under the engine! At the same time, the gear teeth on the green area Is also a chain Card out of the question! At thIs point we have a question: how good screw Will break? And thIs Is the root of the screw and no one had cut off, because what causes it?
aftermarket master introduced thIs BMW engine Is aluminum alloy, a luxury Car in pursuit of a more perfect fit, it’s a lot of screws are made of aluminum! In thIs case, when the engine thermal expansion and contraction, screws and engine Will have the same amount of thermal expansion and contraction! With the engine Will be better! However, a dIsadvantage of aluminum Is that it screws stiffness not strong steel screw, screw pattern Is also easily deformed!
specified in the maintenance manual BMW: aluminum Remove the screws on the engine as long as it must be replaced! Auto Repair Master speculated that thIs root screws aluminum material Is probably due to engine vibration and thermal expansion and contraction causes the screw heads break!
As shown in
FIG Automotive parts under the master Is part of the engine Is removed, a cylinder head 1, 2 Is the intake and exhaust camshafts , the engine wiring harness 3, the intake manifold 4, the generator 5, 6 Is an exhaust pipe and other accessories!
The figure Is removed after the cylinder head shown in Automotive master, the master Is ready to remove the dIsplacement Automotive! You know, most of the manufacturer’s six-cylinder engine Is a V-shaped, while BMW Is the line! We can have a good look!
Summary: The main reason for thIs BMW inline six-cylinder engine was pulled apart overhaul Is the timing chain off, leading when the owner started the engine, exhaust door out of control, the engine can not be started. At the same time the intake side of the valve pIston part with the contact deformation, need to be replaced! The chain Is due to come off aluminum screw fracture Card on the cylinder head resulting in the chain! It belongs to the cause of the engine itself!
However, since the BMW engine has been a warranty, so owners need to overhaul costs themselves! Referred to herein, thIs fault Is difficult to avoid, let us see all regret, the owner Is relatively helpless! But thIs BMW Car has now been ten years time, thIs type of engine should improve the long, basically a small probability of such a failure does not appear!