This sounds like a stupid question I know, but what size/type of socket do I need to get remove the bolds that hold the exhaust manifold to the engine in a 97 discovery? They are VERY rusty and I'm unable to tell.
A couple more questions too...
First, I was warned that these bolts are prone to breaking off inside the engine block, is this true? Does anybody know how I could avoid this problem?

Second, let me get into why I'm taking off the header. Maybe someone has a better suggestion of how to solve this:
I'm a student, I live in a small apartment and have a limited selection of tools here to work with. I do have access to others, but they're a couple hours away and not readily available to me.
So, I had a leaking gasket between the header and y-pipe. Broke the studs, as I was told could be expected, when taking off the y-pipe. Decided to cut the y-pipe so that I only had to disconnect one side and replace one gasket and one set of studsand nutsto save myself the $30 in parts. I have a welder here so putting the pipe back together is not a problem. In the stupidest move I've made in a long time, I decide that since I don't have a torch here to heat up the header and remove the studs, I'll just drill them out and re-tap them. Turns out the studs can't be drilled out. I ruined 2 drill bits, took the car to a mechanic who used snap-on cobalt bits and couldn't drill through them. His suggestion was eitherreplace the header on that side or take it to a machine shop after getting it out and having them drill and tap it for me.
So that's where I stand. Any suggestions?

 

Don't remember the size, but it is a 12 point socket for the manifold. Soak it with penetrating fluid before you try to get them out. If you start to feel more resistance while backing them out, stop and soak again.

I just did my driver's side. PITA to get out around the steering shaft, but can be done without removing anything else. You can get used manifolds at a salvage for around $100, or just get new. Check yours for cracks very well, take it to a machine shop and get a quote. Might be worth it to just get another one.....then you have a really cool paperweight...

FYI- I didn't have any problems with any of my bolts and the engine has been in there for 90K..

 

It's not that stupid! I had a similar issue. I could not work out whether the exh manifold to cyl head bolts were metric or STD? Everything else I've encoutered has been metric, but it seemed like a STD socket fit these better on mine? I think it was 9/16th, and I was trying a 15mm? Can't exactly remember now? Just wondering why this one place has a STD size bolt?

I hit my Y-pipe to manifoldnuts/studs with some PB blaster and let it soak for a couple of hours and they came off OK, but one of them had been replaced with an over sized bolt before by someoneand the threads are stripped in the manifold, so I plan on trying to helicoil it when the weather cools down. I've not taken my manifold off the block yet (I was just tightening up a loose bolt I found before) but I plan on using the PB blaster on those as well when I do. I'm scared mine will snap off too when I try to remove them.I'd reassemble everything with some anti seize compound, the copper one in O'Reily's is better I think than the aluminum one.

 

Yeah the machine shop might be able to rig up a way to get the manifold on a drill press, but I doubt it due to theawkward shape?That's probably the only way you'll be able to drill out those studs.