The E39 525d doesn't have a timing belt. It is " chain driven ". The chain has a tensioner which is self-adjusting and should never need to be replaced. If you have any concerns about engine noises, performance or economy, you should spend £50 at your BMW Main agent for a full health check. You will find that the service is exceptionally good and well worth it for the quality of the car you are driving. I am a new BMW customer and I am very pleased with my purchase.
The 525d E39 model had a M57D25 diesel engine, introduced in 2000 till 2003. This was a straight six and not a V configuration.
The oil dipstick on a BMW 525d is located along the left side of the engine. It connects directly to the engine block and runs down into the oil pan for accurate results.
The water coolant on a BMW 525d is located in the radiator hoses, radiator and engine block. It is circulated via a pump which helps cool and maintain engine temperature.
If its anything like my 2004 525d Tourer, it will be found within the right hand boot (trunk) cubby hole (mine accomodating the first aid kit), under a plastic tray that is removed by unscrewing three nuts.
Turn the ignition on but engine not running. Press the tripometer button and hold for ten seconds, a menu will appear showing the same symbols on your I drive. Scroll to the right symbol the press the button for three seconds this will reset the required function. Press the button again for three seconds to confirm changes, then ignition off and all should be OK.
Manufactured? We're talking in the millions in Europe. Most BMW's in Europe are Diesels and also can be low grade optioned like cloth seats hand crank windows...so you looking at a lot. But if you wanted to know how many are in America that is a hard number to put a finger on but it is very very small possible in the low one thousands.