Hi anyone and everyone, I thought I'd try dipping into the fountain of knowledge before I pull the last of my hair out!!

My 1999 1.8 TDI has been a very reliable workhorse over the years, right up to the point where it cut-out dead on a large rural hill. The fuel pump had dramatically given up the ghost. The car had done 160K and was getting a bit tatty but the engine was a good-un with a new turbo only just fitted. So I bought a much tidier car that had an engine knock, with the idea to transplant my engine.

The 'new' car still started on the button and drove well so I ran it for a few weeks until the noise reached a worrying level. Then the transplant was made. My trusty old engine went into the new car, which retained its diesel pump, starter, thermostat and gearbox. We renewed the front wishbones, discs, pads amd rear cylinders. Filled engine and gearbox with top quality oils and replaced air and oil filter. Then we tried to start it.

It turned over well but wouldn't start until we cracked open each of the injector hoses to bleed the air out. Then she fired up lovely. I took her for a spin and she drove spot on. All was well with the world until I switched her off for 20 mins and tried to start again. She kept turning over whilst belching white smoke (fuel?) without a hint of firing. We made good use of the slope outside and bump started her first time. And thus the pattern was set!

For the past two weeks she has started first time, everytime when really cold. She runs like an express train when started but if I try to start her when warm, I only have a 25% chance of success. She bump starts straight away though??

Can anyone shed some light on where I have gone wrong with this as I can't afford to lose much more hair??????

sounds like a duff temp sensor to me.