Bumper screws stuck, engine job ok

??? Took out my 2.0L type 4 engine yesterday (heavy aren't they?) No great drama, it came out as per expectation, except that I thought I'd take the bumper off for a little more room. Undid three of the screws that hold the bracket onto the chassis. They all did the CRACK (I'm rusty) noise but came out OK. The fourth little blighter went CRACK and then just spun round and round and round without screwing out.
Obviously the threads knackered. Any one had this problem and have any advice as to the best way to cure?
I just undid the two small screws that hold the bumper onto the bracket to shift it for now, so it's not urgent and can wait till the lump is back in and running.

For those interested in these things I am doing heat exchangers, engine mounts, push rod tubes, broken exhaust stud, and I find on inspection a new oil cooler is needed. :'(

 

I'd imagine it's not the thread that's knackered but the captive nut. You'll need to cut the head off, remove the bumper, cut out the old nut and weld in a new plate with a new captive nut.

 

Grotty little job but sounds like the best way to go. Ta

 

I'm planning on taking my heavy 2L out this weekend to do pretty much the same. Don't much like the look of the nuts on the heat exchanger to head studs, I'd hate to break a stud or round off the nut. Lashings of plus gas and a snapon socket will be at hand, but I'd be interested to know how you get on!

 

You will probably find the nut and stud will wind out as one piece
If it doesent want to budge get a bit of heat into it from a butane blowtorch and tighten it ever so slightly before attempting to wind it out

If it then winds out so far but becomes stiff stop spray with plus gas wait a min the gently wind it back and forth a few times till it eases up

Repeat untill removed

 

Paradox is right, that's what I plan to do. As I have a broken one in there already (thanks to PO) I don't want any more! Will post progress although not till next week as away at weekend.

 

Thanks Paradox, that's top advice. Took me all weekend to get the engine out, I'm going to have have a rest before tackling anything else!!