Not starting when warm

[Antonyw]

I’ve got a Skoda Octavia 1.9 Diesel. It’s on a 57 plate and has done about 150,000 miles now. It has always started really well but recently it has been playing up when the engine is warm. It will start up first thing, but when I’ve driven somewhere and parked up it won’t start again. It just keeps turning over and over again. If I leave it for a while then it seems to start again ok. Last time it just wouldn’t start at all....tied it on and off for well over an hour. I eventually had to call the brake down service and of course it started first time when he came. He told me it was probably the crank sensor that was to blame. Does this sound right? I was thinking it might be the glow plugs? Any advice?

[Anddenton]

Could be battery or starter motor. When warm the ECU looks for a minimum crank speed before injecting fuel. When cold this doesn't happen.

[Antonyw]

Thanks for the advice. It just seemed strange how it wouldn’t start at all, and then suddenly it just starts at the first turn of the key.

[flying pig]

I had exactly the same problem with mine and it was the battery. Apparently, a warm engine requires more power from the battery than a cold engine. Sounds strange, but it's true. 

Start with a new battery and see how you go. I think you'll find it'll sort out your problem. 

 

Good luck. 

[Breezy_Pete]

Sounds very untrue to me, who told you that? 

[seriesdriver]

As said in 1st reply the engine needs to cranking at a minimum speed when warm to inject fuel but not when cold and I believe it is black and white 799 rpm on starter no fuel 800 fuel (my figures not accurate or correct) 

 

Check earths and Battery  and replace battery if needed is simplest at worst it may need a new starter. 

[J.R.]

41 minutes ago, Wino said:

Sounds very untrue to me, who told you that? 

 

A flying pig

[flying pig]

It's a well known phenomenon which has been discussed on here many times. Have a search through the forums and you'll see. 

[SuperbTWM]

3 hours ago, flying pig said:

It's a well known phenomenon which has been discussed on here many times. Have a search through the forums and you'll see. 

 

The only well known issue is the fact that the starters on this era of cars can be very poor and don't crank fast enough to start the engine when warm(this one hasn't done bad at 150K) As @Anddenton has pointed out above, its to do with a minimum crank speed required for warm engine before diesel is injected not because a warm engine needs more power the turn it over.

 

 

 

 

 

 

[J.R.]

Mine cranks very slowly when cold but as it always starts on 180° rotation (PD quick start function) maybe its just the initial inertial resistance, it feels like a failing battery but if the vehicle has inadvertently been left in gear the starter will easily overcome the handbrake, when I deliberately ran it out of fuel it cranked healthily when hot.

 

Hot compression is likely to he higher than on a cold engine so maybe the initial cranking load might be higher.

[Antonyw]

Thanks for all the advice. Hopefully I’ll be able to sort it out.