Could I clean a crusty cast iron pan on my charcoal grill?

I don't know. Long ago I bought a bunch of cast iron pans, still have most of it, from some guy selling army navy stuff out of a quonset hut on ninth and Colorado in what is now a richy place, Santa Monica. I mostly am mad at myself for giving away the pancake pan that fit over two burners.

I did whatever I read about seasoning them and life was fine. I messed up a middle pan and it's gradually coming back to even.. after I looked up what to do, which was season again.

Once revisiting L.A. I stayed at a neighbor's and helped him cook and, good grief, he had a quarter inch of oil over his cast iron pans. (He was a marine, and adamant.)
That was quite a stay - 911 woke us up (in our separate rooms should there be interest) and I found out I had breast cancer that visit, long ago now.

Anyway, I figure there are sites that tell you what to do about this.
I'd be interested in whether you should - or should not - just wire scrub it off with those wire scrubs you find in grocery stores... and then re season.

crusty in the sense of rust or crusty in the sense of cooked-on crap?

Cooked on crap. This pan isn't rusty at all. The high ridges along the bottom of the pan prevent any serious scouring.

I'd give it a go on the grill.

I might give it a try as an experiment since the pan only cost a few bucks (still, I'd hate to lose it).

I have a couple of pans and a couple of dutch ovens that were my grandmothers. They're a bit crusty and I don't mind that crust at all so I kind of get your Marine friend.

Have you tried mixing up some baking soda and water into a paste and working it in? I just cleaned the bejesus out of an old Dansk pot with a baking soda paste - the inside is almost blindingly white now.

I know enamel isn't the same as cast iron - but baking soda won't harm anything if it doesn't work out - and it is amazing at getting food gunk off things. Just make sure you brush off all of the baking soda before you put the pan on the grill.

I don't think you'll lose it and ehBeth's point was a good one.

On the marine friend, it was the level of oil he kept at all times in the pan that threw me for a loop. I can see a coat in locales with a lot of moisture.

Here in dryville, rust doesn't even occur to me.

A paste of kosher salt and water and a wire brush for cleaning BBQ grills should also do the job. Sometimes, for really stubborn gunk, I've used lemon juice in place of water and let the paste work overnight before doing any scrubbing.

Be sure to re-season it with oil afterwards.

If it is really really bad, this site gives solutions ranging from vinegar, to a wire brush on a drill to sandblasting.

http://cowboyandchuckwagoncooking.blogspot.com/2011/01/restore-and-clean-cast-iron-cookware.html

How would everyone feel about oven cleaner left on the grill overnight in a plastic bag? I don't even know if they still make the stuff, but it used to do a job on the trivets on a gas range.

I'm just looking for a lazy way to do it. Since the self cleaning oven cycle will remove most gunk I thought maybe the heat/flame from the grill might work the same way. I know you can use cast iron over an open flame so I don't think it would damage the pan.

I thought about the oven cleaner method. From what I've read you have to spray it down, wrap it in a garbage bag and let it sit for a few days. With the pets/wildlife around here I felt a bit off about having something like that laying around. Plus, once done you have to scour off all the rust it produces. I also worry about being able to remove any oven cleaner residue.

Everywhere I've looked recommends self cleaning oven or oven cleaner but it makes sense (to me) that the grill would work.

I think I'll try it as an experiment. Nothing ventured, nothing gained!

If that doesn't work, I recommend what B-fly said. Kosher salt and a tiny bit of H2O to make a paste.

It what I use.

How do you know the grill is Jewish?

Yes, but you'll want to oil it too. It's one thing to clean it however, with out seasoning it, it will quickly rust again.
You can throw it straight into the coals. Let it cool, brush off the loose bits and then apply some oil. Just enough to give it some sheen, not dripping. Then put it back on the grill for about 20-30 minutes, wipe it off, apply new oil and do it again, several times.
Nothing will stick to it.
Look up how to season a pan for specific instructions on the net. I've done this in the firepit and then in my oven for the seasoning...
Sometimes, if there is a lot of gunk, you can use a 1/2 cup of ammonia in plastic bag, let it sit over night, outdoors or in a well ventilated spot (in case of leak) and scrub in the morning, then season.

Cast iron frypans are supposed to look that way!!

Don't worry about the outside. The inside of the pan should be smooth and black. You aren't even supposed to use soap on these things. Wipe clean & oil.

I've become addicted to cast iron cooking in the last month. I have three, and my boyfriend made lamb chops in one tonite. Wonderful!!

Good to know that the coals won't wreck it. Thanks!

I'm thinking I'll just season it in/on the stove the way I do my other pans.

I have a lot of cast iron so I know how to care for it but I've never had one quite so crusty before.

This crust is on the inside....

Then I would fill it with water and bring it to a boil and then scrape the stuff out.

Be sure to season the pan afterwards.