Other-Power wrote:Had a similar problem with my van when i first got it.
One morning it desided it wasnt going to start and that was that. So i ordered up 4 new glow plugs £30 with P+P. Next day got them and changed them over to find that only one of the plugs was still working, so my van had been turning over on just 2.
After changing the plugs it was great, the enigne turned over first time everytime, then slowly got worse. I desided to chech the wiring runing up to the plugs and found that the extra load of all four plugs working combine with 27 year old wiring ment very very hot wire and a very white fuse.
I changed all the wiring and doubled up on thickness put a new fuse in and now the engine starts better then ever.
If its a turbo diesel there will be 2 relays inside the box, the heaterplug relay is the tall one (the other one is a normal relay and triggers the aux water pump when the starter motor is running to stop it seazing up through lack of use aparently - completely pointless as if its working corectly it'll probubly come on anyway once the engines warmed up thus already gets enough excersise.)
Aux water pump only runs when the engine is stopped, and only then if the engine and oustside temp is hot enough for the water temp to keep rising (heat soak) above a set temperature, which then triggers the pump to circulate the water round the system to bring it back down to a suitable temp, supposed to stop head cracking probs on TD motors
That`s what the extra temp sender is for on the TD motor.