Long cranking times

I have a 1999 jetta 5 speed, when cold the motor fires right up but when warm it seems to crank about 4-5 seconds before it fires up. It does not consume any oil and runs perfect, could this be glow plug related? car has 135k miles and the injection pump and belt have about 10k.There are no codes present.

When its warm does it crank slower

Also if you have the clear fuel feed line , after you shut the engine off take a look a that line , check for air .One small bubble is common . Fuel filter been changed lately ? If you see excessive air ,could be a bad o-ring on the Tstat valve ( the black plastic valve on top of the fuel filter ).

I don't think it is GP related because when it's warm they do not cycle on regardless of the indicator light and most any time there is any fault in the GPs, harness, etc. the CEL comes on within a few seconds of starting the engine. The suggestions above should be checked out as well as the injection timing with VagCom. Above the middle line, slightly advanced.
It can also be an indication of a failing starter.

crm391 said:

I have a 1999 jetta 5 speed, when cold the motor fires right up but when warm it seems to crank about 4-5 seconds before it fires up. It does not consume any oil and runs perfect, could this be glow plug related? car has 135k miles and the injection pump and belt have about 10k.There are no codes present.

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My guess is the battery.

Motor turns over at same speed as when cold, new starter 5k ago, new fuel filter 5k ago, will check for air in system from fuel filter valve.How long should the Gp light stay on when cold?

Clean (-) battery pole. Those MKIV have ground issues after few years.

Is the car an A4? If so it sounds like you have a "hard to start when hot" problem. Search for the words inside the quotes.