...520i 1996 model.i only just bought it.?
i did not have a manual with the car.
thanks for the answers to my question,yes on the one answer the engine number is always on the log book (v5) but when bought the engine had to be replaced. therefore i am making sure the garage that carried out the works has put in a replacement engine not repaired the old one.because the engine number thats on the engine now if replaced will not match the one on the v5. all engines have different numbers by law. this has to be located to inform the dvla to update my v5. i should have highlighted this when submitting my question, sorry and thanks for where it is located to. cheers to you all.

BMW 520i worth: $30,000
BMW owners worth : $100,000
Finding the engine number: PRICELESS

There should be an emissions sticker under the hood, it's required to be there by law. It should show the type and number of the engine. Look for a white sticker.

The BWM engine numbers are found on the steel rib just above the OIL PAN on the right side of the engine close to the radiator and beside the A/C compressor and timing chain (or belt) adjuster screw.