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Non Start When Engine Warm...



Hello again folks, same old topic but maybe a clue helps...

Go for a drive for a couple of miles. Stop, switch off have a cup of coffee, or leave her for a couple of hours, doesn't matter she starts, not immediately requires a second or two to fire but away she goes.

Drive long enough, for the engine to warm up (eight miles or so) park up and bingo Quick start required to wake her up.

Goes like the clappers warm or cold, 

I am fairly sure it's not machanical, lets face it the old girl is 60% computer hardware, 20% software, 10% cable and 7% mechanical (have excluded the carpets).


I have bought another GV (with gear change problems as a donor (2006) with the intention of switching out sensors one by one, does anyone have any ideas before I start the swap overs or which sensors, solenoids I should start with ?

The donor has an electric rear door so was thinking of swapping this but it's a different colour (green) and has privacy glass so have filed away as a to do (maybe). 

It also has a multi cd player as well as the standard cd player (same radio and cd as mine) so another question, can I just fit the multi cd to mine or will the ECU or whatever throw a wobbler ?


Also, removed the fuse box from the donor and there is a relay behind it (against the flitch), cables appear to be 




DG/BL           my colour sense on old cables isn't the best but have searched both LG and DG combos;  have searched the manual and these colours doesn't make sense (mind you there is a lot in the manual that doesn't make sense....)


I am inclined to pull the fuse box on the old girl and see what's hidden behind that one!


suggestions greatly appreciated.






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Hi Richard,


Welcome! Others will probably stop by and help, hopefully my memory of these beasts will help, sadly I no longer have my own.


So this is one that has cropped up from time to time quite often. It's also a problem I had on my old CGV (The second one I owned). Same thing, it's a warm start problem and it's very repeatable as you describe.


My suspicion though is it was mechanical. When hot there is expansion in most components, and in my thinking it's down to poor compression why it won't start. It just turns over and over, it occasionally tries to catch but then dies (If you listen carefully to the engine you can hear it almost catch then immediately fail and back to starter motor just spinning the engine).


If I still had mine I'd be starting to look at the cylinder head gasket or even cylinder rings getting worn and loosing compression when hot. Once engine is running it sort of self-heals as it's not as noticeable but when starting that's when you need it most.


BUT after all that, sensors also deteriorate when hot so your thinking of swapping sensors is logical. My first thoughts would be the PRV on end of the diesel rail, the crank and speed sensors too, one by one is sensible here. All of those can affect the startup and are also sensors very prone to temperature related failures.


On the radio/CD you should be fine fitting. You'll need the code from the old one though. The codes are normally stored in the ECU and 'pair' when they connect up, fitting a different unit I suspect will trigger the need to enter the code, which if you don't have the original manual/code doc for the donor car might not work, but I'd say give it a go.


I recall that relay you mention but cannot for the life of me remember it's function. I'll see if I can find out!




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Thanks or the reply Andy, the Pressure Relief Valve was changed some months ago before finding the original cold or warm no go was caused by the primer pump on top of the fuel filter housing had a split diaphragm. Any idea how accessible the crank and speed sensors are AND.. why does it kick off straight away when wafted with some Quick-Start ? dur...............

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Thanks for the reply

As the MOT is due hence having to get it into the shop I think I'll replace the pressure regulator, crank sensor, camshaft sensor and pressure regulator at the same time. If that doesn't cure it then a small fire might resolve all problems...... Aaagh..

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Yes, I know what you mean. Today was doing some diy work as also need to pass MOT. Was doing some welding works and Airbag sensor was giving troubles. Have noticed that transmission pipes are wet in oil. The ones that goes in from oil radiator. Touched one just to check how tight it is and its broken in my hand. What a disaster. I was also thinking about a small fire that moment.

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