The story goes as: (n52)
New client car gets tow in it cranks with no start after broken acc drive belt. I Check Battery, all sensors etc Scan test say cam sensor syn both intake and exhaust recheck and do all test to electrical on engine nothing wrong and still cranks with no start.
Next step I wanted to check mechanical timing. Remove valve cover and first concern lack of oil film and wetness on valve train. Then I find this mess in the timing chain and guides.
![Click here to enlarge]()
At this point it looks like acc drive belt in the chain??? move on to remove oil pan and bad news bears:facepalm
![Click here to enlarge]()
![Click here to enlarge]()
![Click here to enlarge]()
Not sure what to think or how belt got in? Decide to remove crank pulley .. BOOM
![Click here to enlarge]()
The belt broke and wrapped itself so tight behind the crank pulley it pushed itself pass the crank seal and shredded it self inside the engine. Damage found: broken and cracked chain guides, tiny belt chunks everywhere and worst of all oil pick-up tub heavily restricted but belt debris. Remove rod bearing cap and find bearing damage due to oil starvation. So please check and maintain the acc. drive belt and tensioner. Don't be dumb and drive it home after the belt has broken to get a tow truck. This is the first I've seen this happen but the bmw dealer I deal with has seen this 3 or 4 times
![Click here to enlarge]()
![Click here to enlarge]()
New client car gets tow in it cranks with no start after broken acc drive belt. I Check Battery, all sensors etc Scan test say cam sensor syn both intake and exhaust recheck and do all test to electrical on engine nothing wrong and still cranks with no start.
Next step I wanted to check mechanical timing. Remove valve cover and first concern lack of oil film and wetness on valve train. Then I find this mess in the timing chain and guides.
At this point it looks like acc drive belt in the chain??? move on to remove oil pan and bad news bears:facepalm
Not sure what to think or how belt got in? Decide to remove crank pulley .. BOOM
The belt broke and wrapped itself so tight behind the crank pulley it pushed itself pass the crank seal and shredded it self inside the engine. Damage found: broken and cracked chain guides, tiny belt chunks everywhere and worst of all oil pick-up tub heavily restricted but belt debris. Remove rod bearing cap and find bearing damage due to oil starvation. So please check and maintain the acc. drive belt and tensioner. Don't be dumb and drive it home after the belt has broken to get a tow truck. This is the first I've seen this happen but the bmw dealer I deal with has seen this 3 or 4 times