External bearings unscrewing

[Easytigers]

Went out for a ride today with a friend who has just bought a second had Bianchi. After a few miles the external bearings (I think this is what it's called) had unscrewed on the left side and was forcing the pedal arm off. Tried screwing the bearing back in and tightening the pedal back on but after a few more miles the same thing happened! Had to abandon the ride and took a shortcut home.
Anyone got any ideas?
Many thanks and apologies for the lack of accurate terminology (love cycling - hate maintenance!)
Russ

 

[accountantpete]

1) Use pfte tape or threadlock to secure the external bearing cup.

2) There is something wrong with the bearing - the outer bit of the bearing should stay stationary in the cup whilst the central bit goes round with the cranks. It sounds like the bearing is seized and the outer edge is revolving and turning the BB cup with it. Also check that the bearing hasn't been seized for some time and worn away the axle.

 

[Easytigers]

1) Use pfte tape or threadlock to secure the external bearing cup.

2) There is something wrong with the bearing - the outer bit of the bearing should stay stationary in the cup whilst the central bit goes round with the cranks. It sounds like the bearing is seized and the outer edge is revolving and turning the BB cup with it. Also check that the bearing hasn't been seized for some time and worn away the axle.

Not quite sure how to do what you said (I'm so incompetent!!!) Do know what ptfe tape is though and will give that a go! thanks and sorry for lack of knowledge (hopefully though will know for next time!)
Russ

 

[accountantpete]

Not quite sure how to do what you said (I'm so incompetent!!!) Do know what ptfe tape is though and will give that a go! thanks and sorry for lack of knowledge (hopefully though will know for next time!)
Russ

just make sure that you take the cranks apart and inspect the left hand bearing - if it is seized you will ruin the axle and need a new chainset.

 

[Easytigers]

That sounds bad...very bad! Will have a good look (only saving grace is that it isn't my bike!!!)
Thanks accountantpete btw!