seized engine bolts

[bigredd]

hi, ive several bolts that are seized in the crank case of a honda, the bolts that fasten to the mounting brackets. can i heck shift em! i took it to a garage and a week later they gave me it back and said they couldnt move any of them! what now? i completelly stuck

[TBS]

Have you tried serious heat to the bosses whilst trying to turn the bolts, best use oxy acetalyne but be careful not to melt the cases.

[m3bobby]

If all else fails you could split the nuts, they should be metric threads so replacement shouldn't be to difficult.

[Goldy]

Another option is to drill them. if you start with a 'sharp' small diameter drill , centre punch as accerately as you can on the centre of the bolt and drill into the bolt. Open up with larger diameter drills until you can break off the nut or 'collapse in' the thread.

[DevonDan]

And hit them to try to spring the threads.   Are these cross head screws or hex bolts? Those old Japanese cross heads were a pain, but if you drilled them out the remainder usually came out with a pair of mole grips.

Dan

[bigredd]

cheers for the replies fella's. to give you an idea ive managed to remove a couple of the nuts 'hex type bolts' but the bolts are about 6 inches long and the actual shaft of the bolt is fused in the crank. ive uped the anti and dropped it off at a local bike shop/engineering firm. if it fails to budge this time i may have to look for another bottom end. bugger.

[RichP]

Have you thought about Spark-erosion ? Try Googling it.

If you've been able to get the engine out of the frame, a barrel of diesel for a month is the traditional loosener.