I also had a couple instances yesterday where my tank was repaired up to over 80%, but it was still disabled and losing health. I thought getting it up over the disabled threshold put out the fire and removed the disabled status. Maybe it has to be 100%, because that is all that fixed it.
May 6, 2013
Something that bugs me about playing engineer in BF3 is that I often do not get that image on my HUD that indicates the damage status of the vehicle being repaired. I find that I am sometimes standing outside a tank trying to repair, but I have already finished. I do not know if that is because the person in the tank also got out to repair, or if it is a bug. I believe the game is set up so that you do not get the HUD image if no one is in the tank, because I never get it when I am solo in a tank and get out to do my own repairs. It seems to me that if it is a friendly vehicle, even with no occupants (meaning the last person it is was a friendly, yourself included), you should get the repair HUD regardless.