My Ford 1910 has always needed 20 seconds of pre-heat to start and this has always unsured a prompt start. Until this week! I noticed the engine turning over quite a few times before it would start even with the pre heat. The check wire on the dashboard still glows hot and I have taken the aluminium contact strip and the glow plugs out to clean all the electrical connections with a wire brush and a knife. Having put the glow plugs back I noticed the the closest one to the electrical connection always got hot, the middle one got hot after I cleaned the contacts and the end one at the front of the tractor didn't get hot at all. I tried the front end glow plug in the first position (nearest the electrical conection and seat) and the plug got hot which suggests that the plugs are ok but but the electrical current is not - but I can't think what else I can do to isolate and fix the problem. The tractors starts instantly when the engine is hot from work but still labours for ages without firing when cold before finally firing into life - sometimes with a second burst of pre heat for 10 seconds in addition to the original 25 seconds.
Any ideas greatly appreciated.
Any ideas greatly appreciated.