My 2002 323 turbo diesel has done 53k miles and is due a service at the end of the month. Lately, however the engine is slow to start from cold, whereas up till about a month ago it always started on the second turn of the key from very cold and instantly when warmed up. It always starts but only after holding the ignition switch on for up to 5 seconds. Even whe the engine iis fully warmed up it takes two turns to fire up. Anyone know what the problem could be? I'm worried that the glow plugs need replaced and these cost c£45 each! My hope is that it's just the battery that needs renewed.

Cheers

It's not likely that all the glow plugs acted up simultaneously, so check the cranking voltage. Do it at both the battery posts and the wire terminals. A weak battery whose voltage drops below a certain value while the engine is cranking can also give the same symptoms because the plugs need full voltage to work properly.