Hi, I’ve got an issue with my Ford transit custom 2014. Occasionally while cranking it will make a knocking noise and not start. It never happened on a cold start after sitting overnight. I read somewhere it could be the timing chain tensioner which made sense to me. I took it to a mechanic who said they checked the timing chain by turning it over by hand and they seemed to think the noise was flywheel side pointing toward dmf noise. I asked why this was causing a no start and his reply was could be a bad earth strap or something similar. Has anyone else experienced something similar? 
many thanks

Does it start straight away if you stop cranking and then give it another go?

I had something similar with an old car, where the popping noise was just the compression without any fuel being injected to create combustion.

Happened on pretty much every warm start.  I didn't keep the car long enough to find the fault but it was just the ECU failing to fire the injectors for some reason.  (Checked battery, starter and cables and all fine).

If it is the DMF knocking you should be able to replicate it while driving by labouring the engine using too high a gear for the road speed.

 

Hi , thanks for the reply. Previously it did seem to be ok on the 2nd turn of the key. But recently it seems to be getting worse and More common and it can take 3 or 4 goes before it will fire . It’s quite a loud mechanical clunking almost like the starter motor isn’t engaging properly. But strange how it has never done it after it’s been sitting over night. 

The starter is at the DMF end of the engine, so could be that failing to engage fully.  Though should be easy to see as the aux belt won't be moving quickly or smoothly.