Retapping holes

FWIW it's an iron block and it's quite close to the gearbox, so access is tight - not got a tapping set at the moment so unsure as to if it'd make any odds.

You can often get away with this sort of problem by aralditing in a length of studding (degrease the hole well first) and using a nut on it (with suitable washers / spacers if it is a steel sump with a lip which would foul the nut). Works on sumps, timing chests, thermostat housings; anywhere where there isn't too much pressure.

Often there is some of the original thread left deep inside, if you put a stud into the hole (I would use threadlock too) and use a nut to hold the sump on it will be fine. There may be enough room to go to a larger size, but it would be preferable to keep to the original, either using a stud instead of a bolt or helicoil it back to the right size (probably 6mm)

mrcheerful

That's an interesting idea. There are 20 bolts, so it's not as if they're taking great amounts of strain. Next time the sump gasket won't come from ECP (how the f*ck do you make a sump gasket with too few bolt holes?) and there'll be some liquid gasket involved. I reckon a small amount of oil is blowing out from the gasket somewhere...

Anything to stop me using a longer bolt (other than the possibility of not knowing how deep the hole is and ending up with too much stuck out. I'm keen to avoid helicoiling and drilling away at an engine block on my back isn't what I'd call a good idea. Too much possibility for a hole at a stupid angle...

The message from "Doki" contains these words:

Test it first!

The thought had occured to me at the time of posting. I was thinking more along the lines of the existing thread not being able to handle a bolt being done up and undone repeatedly perhaps being the reason for using a stud instead.