as Fat120y said add some heat, welding a larger nut on helps. as you have the heat of the weld, plus you can use a large spanner

Pity I dont have the skills or equipment for welding....do have a heat gun. But I don't think 400C would cut it for heat - I think if your gonna heat it, it will have to be red hot.

If you cant get it out by the methods mentioned above and you have to use heat you will be surprised how little local heat is needed, a good hot air gun should help. The alloy will expand at a greater rate that the steel plug, plus it will help soften any sealant that may be bonding the plug in place. They are designed to be tapered so the further you screw them in the tighter they get. Overtightening only leads to the case cracking around the thread and you always have oil leaks. When putting the plug back, a little sealant and moderate tension is all thats needed.

Hmmmm cool - I might add the heat gun to the arsenal then. Looks like a post-cruise task now. Thanks all for the suggestions.

I dont think heating it will help at all, firstly heating the plug will make it expand at a greater rate than the alloy housing . Alloy is used because it disperces heat better than steel.
I would get a single hex socket (preferably one for a rattle gun) and make sure it fits perfectly and a decent breaker bar.
Give the plug a good sharp hit to loosen it and get a good position so you get the most leverage.
it that fails go and have a beer.
ade

I use an eight point socket on a 1/2" breakerbar and piece of pipe on the end if needed.

Quote:
You dont focus the heat on the plug, you heat the alloy around the plug. For your info the co efficient of expension of alloy is greater then that of steel - google it if you dont believe me.
Simple, thats why I suggested that "not much heat" will be needed.

OK I stand corrected, I had not explained myself correctly.
If a nut is welded on to the seized plug the steel plug would retain its heat longer than the alloy housing, do you agree that would make the plug tighter and therefore harder to remove ??
ade

ade,
Firstly my reference was to the use of a heat gun localised around the alloy around the outside of the steel plug, not to welding anything to the plug itself.
If you were to weld a nut to the plug (which I wouldnt suggest) then the plug will get hotter than the alloy. However once the plug temp lowered through heat transfer to the alloy case, there would be a point in the heat transfer process where the plug would be easier to remove than if done at room temp.
Welding anything to the plug is getting really desperate and there are less dramatic ways of removing frozen drain plugs Thats why I mentioned that some members might be surprised how "a little heat" can make a difference when removing steel plugs from alloy casings.

i agree with freak hit the bung with a hammer half a dozen times (careful not to crack the housing) the get the biggest shifter on that u can and flog the piss out of it (the handle of the shifter) while holding as much pressure on it that u can. i spend a portion of my day removing all the ####ed out bungs off trucks and thats just what works for me either that or 6 foot of pipe