Ok I have noticed this and have been wondering why for awhile? The 603's need to go through the complete glow cycle regardless of temp of they will skip and complian after you start them. While the 617 on the other hand doesn't seem to mind this, if the engine has some heat in it you can almost skip the glow cycle?
What did MB change? The glow systems are similer, I know the 603 has a different head design maybe that is the cause? I think the glow plugs are even that same?
Any ideas?