Car won't start... complicated problem?

Question

Before going to a mechanic to spend 1000 £ on parts that I don't need to replace... I'd want to understand the problem first and ask here.

Car battery is good, always good charge on it and CCA, car always starts from cold start no problem (2 liter 2011 passat, diesel), but after a long 1-2 hour drive when the engine gets around 90 degrees, if I turn off the car for a few minutes... it will crank, battery is good, even got a power booster, but it keeps cranking, cranking, cranking.... refuses to start. I have to wait about half an hour until the engine temperature gets around 70-80 degrees and then I can just barely start the car. I don't have to keep the key in egnition to warm up the engine, I can put the key directly, sometimes it might take a good few 5-10 seconds to start, other times only takes 1 second.

Fuel filter? Glow plugs? Starter? I can't figure out. Ideas? thanks

Skoda John · Answer

Sensor fault.
A good garage will plug it in and find the fault.

thebax2006 · Answer

A diesel normally starts easier once it's warmed up. You can't guess at something like this. You may have leaking injectors or some kind of problem with the electronics that control the power to the glow plugs.

Anonymous · Answer

Check for a bad starter.  Engine speed might not be enough when starting when warm.  No joy, check sensor data when cranking with a scan tool when engine is warm.  Could be a bad crank position sensor or fuel pressure regulator sensor.

Anonymous · Answer

If it starts ok from cold the glow plugs are fine. Change the fuel filter just in case. I suspect it's either a high pressure fuel pump issue at a certain temperature or the ECU has got it's knickers in a twist and is malfunctioning according to the engine temperature. You can ask a dealer or any good garage to interrogate the ECU to read fault codes. This should point you in the right direction.

Car won't start... complicated problem?

4 Answers