Glow plugs.

Afraid I can't help you much here mate. Can only offer that many times folks change glow plugs before they actually need to. If you're having problems starting your B, then ok. Just make sure it's the glow plugs and not the plug wires or something else. It does not typically get THAT cold in GB, but I'm not sure where you're at either as I realize it does get somewhat colder in the Northern parts. Just hate to see you go through the expense of changing plugs if it's not necessary.

Would a block heater serve you better than glow plugs?

Getting the engine to a nice warm temperature sure makes starting easy.

My IH (made in England) has an external heater,,,



Plug it in when the tractor is 10 degrees F. for 30 minutes,
the tractor starts like it is the middle of summer!! :fing32:

I just added one of these to my JD 650,,,



This heater cost about half the price you showed for a glow plug,,,

I tried it out for 15 minutes on a chilly day last week. The engine was nice and warm.

Thank you both so much for your replies.....it was a couple of times last year when i had problems starting the tractor, it was just below -5 and the tractor didn't want to fire on all four cylinders for a while, so i thought it could be a plug issue.
I did have someone come and test the plugs yesterday, as a favour, but they only had one of the testers that light up, so i don't think that is telling me everything i needed to know. He said each plug lit the tester, so each plug was fine.....
I will look into a block heater, but i take it they plug into the mains supply and as the tractor is parked well away from the house this could be an issue.

Thanks again for your help and advice.