os 50 head bolts rounded

[olly]

Having a nightmare trying to get the head off my OS 50. Got 3 bolts out but the other 3 were so tight they have rounded. Has anyone any suggestions for my next step please?

[vanman]

I had 1 do this to ,I drilled the head off the bolt and then the head lifted off and i removed the bolt with vice grips hope you get it sorted

[dillwhacker]

You can try using an imperial 'next-size-up' hex driver, see if that can get a grip.
Or maybe get the next size up metric driver, grind 6 little tapers onto the end of it with a Dremel, and see if you can tap it into the head to get a grip.
Also bung the head in the oven at 100 - 150 deg C - the ali will expand more than the steel bolt, which might help, or at least soften some of the goo.
HTH
Good luck!

[moyesboy]

if you have a torx screwdriver bit set there is one that is a tight fit in an m3 socket head. Thats how I got one out of mine.

[jimmyhorns]

All three of these are good ideas and have worked in similar situations for me.

you are going to need new bolts anyway, so I would be tempted just to drill them out.

If you do this make sure that you tape over the carb, cover as much of the engine as possible, and leave the glow plug installed to stop metal shavings getting where they arnt wanted. A little slither of metal in your engine is not going to make things pretty, if you dont see it when you take the head off.

[dillwhacker]

The trouble with drilling steel bolts out of alloy is that if you do it by hand, the pressure required to drill the steel is so much that if the bit slips, it gouges through the ally like mad, and then you have made a ski-slope from steel to ali, which is really hard to stop the drill bit from following.....
Good luck !

[Spanner]

Torx T20 bit (I think) hammered into the rounded bolt head worked wonders for me last bearing change :-)

[helijohn]

This job is a PITA and once the allen head has been rounded often nowt really works when I have had this problem on other things so I would probably end up drilling the heads off. It is a pity there isn't room to get a Dremel grinder in there.

This begs the question, what can you do to prevent the problem recurring? Would you use something like Coppaslip??

[olly]

Thanks very much guys for all your interest and suggestions. One of my flying club members (Challener Brothers, Heaton, Meresey, Stockport 0161 432 1263 Try Them !!!!!) has a car repair business and workshop and he succcessfully removed the bolts this morning, using the following method. Heat the head in boling water, then tapped a torx driver into the bolt head and easily removed the bolts....simples...eeech!!!

[moyesboy]

ALL os 50 hyper parts are more or less freely available through this forum except - crankshaft, bearings, piston, ring, liner, and head (but you can get free heads if you arn't fussy about fragments of all the previously mentioned parts being embedded in them).