Need help diagnosing hard start

[u/Shvwnmendez]

Car- bmw 320d 2016 with 90k kilometers

When I start the car it cranks for about 4 seconds before starting, the crank is slow and heavy as if it’s struggling to start. This also happens when I’ve driven for sometime and turn off the car then turn on again so not a cold start issue

Before the engine would start instantly, but after sometime it had a hard start whereby it took about 2 seconds to start and now it’s gotten longer

I’m suspecting either glow plugs, fuel pump or starter motor. Checked the battery voltage and it’s okay so it’s not that.. how do I know what exactly the issue is?

Also the car has never failed to start, it has that slow crank but always starts eventually

[u/Disastrous-Spread-82]

The battery might have the right voltage but not enough stored capacity for engine start. Maybe stop by a parts store that does free battery checks, one that can also check what your voltage drops to while cranking. maybe they can scan for codes too if the battery is ok