Hi all,

Looking for some help diagnosing my 2003 Discovery 2 TD5.
The symptoms started a while ago with rough, hard starting first thing in the morning, along with a small amount of white smoke. Once it fired, it ran fine for the rest of the day and would restart without any issues.

Over time it gradually got worse. Every start became difficult – even if the vehicle had only been left for an hour. The white smoke increased, and I also noticed a slight coolant loss, but no oil/coolant contamination. Initially I suspected a head gasket, but I was advised to check injector seals, fuel system etc., so I went down a long fuel-related rabbit hole.

So far I have replaced or checked:

• New fuel pump
  
• New fuel filter housing
  
• New injector seals
  
• Injectors removed, checked, and cleaned
  
• New crank position sensor
  
• New starter
  
• Bled system repeatedly
  

No change at all. Eventually it reached the point where it wouldn’t start at all.

While cranking, I noticed breathing from the oil filler, which pointed me back toward the original head gasket suspicion. Removed glow plugs and found glow plug No.4 was covered in oil.

Compression test results were:

• Cylinder 1: 150 psi
  
• Cylinder 2: 200 psi
  
• Cylinder 3: 200 psi
  
• Cylinder 4: 260 psi
  

Pulled the head, had it pressure tested (all good), fitted a new head gasket, rebuilt everything… and now the engine still won’t start. It cranks but there’s no cough or splutter. Just a few small puffs of white smoke — nothing like the clouds it produced before the gasket was done.

So at this point:
New head gasket
Head tested OK
Fuel system overhauled
Injectors checked
Still no start

What are we missing? Any ideas or similar experiences would be hugely appreciated.

Thanks in advance.