For 2 years I have stubbornly trying to solve slow starting on my Scout 1.9 BSW engine. Slow start first thing then OK rest of day .Starting with replacement glow plug loom after finding shroud ends cracked and broken. Next glow plugs even though resistance readings were correct ,followed by glow plug relay. Then the coolant temp sensor. , followed by MAF sensor . Next replaced fuel lift pump and fuel filter.

It was only towards the end of my investigations in a car park when nothing happened first turn of key did I think starter motor. And that's what it was as fitted new starter and engine start is immediate.

Luckily all the parts were relativity cheap and I now know what all the sensors on the car do where as before I didn't have a clue.

I should add prior to my investigations I did install a new battery to no avail! After that I later purchased a proper battery tester to check cranking power. Also the starter motor was described as an uprated one ie from 1.7 to 2 KW if I remember rightly.

Possibly/probably cranking speed too low, if too low, heat of compression especially on a cold start is lost through the cylinder walls.

I remember well, in the 60s, the Standard Ford Major Tractor had a decompression lever, there were two levers, in cold weather/first start in the morning, you used one lever to decompress by keeping the either (can't remember which) the inlet or exhaust valves open, you then used the other lever to crank the engine, after a few seconds, you released the decompression lever, and away you went. With a hot engine you didn't use the decompression lever but after many many thousands engine hours and wear it was difficult to start when hot even with a new battery but once you increased the cranking speed by using the decompression lever then no problems.