Hi. Haven't noticed any patterns with parking on hills, as I've mainly parked on a flat surface, but the starting time does vary even on flat surfaces.
How can someone check if there is an air leak in the fuel system?
One thing that I've been aware of is that when the problem 1st started - I took the van to my local mechanic to have a quick look and suggest a fix. They tried to get the glow plugs out but said they were too stiff, and they were worried that they might snap inside the head. They also said that they wouldn't have been able to get all the plugs out as they were concealed and hard to get to.
When the dealer garage had the van for a few hours they said that they had checked the glow plugs and had them all out. - I find this hard to believe, and i am now thinking that they may be aware that the glow plugs are stuck in, and that snapping them would mean 10 hours labour to get the heard off. Therefore they are just fobbing me off to save them doing the job.
There are only so many things that will make a diesel have an extended crank time when cold. Air leak in the fuel sysytem, weak bettery causing slow crank speed, and no glow plug operation.
Air leak in the system is hard to diagnose, easiest way to tell is with gravity. Being that you park flat surface, I doubt this is the problem.
Battery needs to be tested at half of the cold crank amps for 15 seconds with at least 10V. If not, replace the battery.
Glow plug operation on these newer VW diesels only operate when temp is down to 40-45* F or below. So if it has been warmer than this, probably not glow plugs.
Hope this helps out a bit more.