long cranking (starting) time

during the winter, when trying to start my 2002 Jetta GLS TDI 59,000 miles, after turning the key to "on", the glow plug indicator lamp would come on for a certain amount of time, after which, turning the key to the cranking position the engine would immediately start to fire and then start...now that the mild weather is here, when the key is turned to the "on" position, the glow plug indicator comes on and then almost immediately goes off, turning the key to crank position, the engine will crank so long that the low oil warning tone and indicator will come on before the engine even fires...when it does finally start, there's so much unburned fuel and smoke, that I always think someone's going to call the fire dept. does anyone have any idea what the problem might be?...the car has had its regular services since new at the dealer and I've had it back to the dealer three times, and still no resolve...thanks in advance...Wilf

Has it set any engine codes? There's a common problem with the power strip that connects the glow plugs, the dealer should know about this though.

no codes set...the dealership has looked at cranking speed and replaced the coolant temp sensor....the car is at the dealership now and they've removed the coolant temp sensor, the car starts great, so now they're going to look at fuel delivery...I've told them from the start I thought it was a problem with glow plug dwell time, as there seems to be lots of fuel delivered, visible from tailpipe from from all the raw fuel dumped in there during the crank cycle...Wilf...

definately sounds like a glowplug issue all the way!

thats the only time the diesel smokes really bad when it's being started cold (healthy engine that is)
i'd take it to a different shop to get them to check the glow plugs and power stip they are on.

i'm confident it's that.