MGB Big-ends

[fulvia griff]

I think my MGB needs new big end bearing shells as its got all the signs, rattle at start up and starts to knock louder and louder above 3500rpm. I've been told it can be done my removing the sump, undoing the clamp bolts and bottom half of the big end and then sliding the old bearings out before sliding the new ones in. How feasible is this and has anybody got an experience of replacing them?

[Mr Recovery]

Hi there, Yes you can replace the big end shells this way. It can be a bit of a faff sliding the pistons up the bores a little to get the new shells in and double check their in the right way round with the tabs in the groves etc before tightening.
Whilst you are in there check the dimensions of the crank with a micrometer etc as this will tell you if it's just the shells or if there is a bigger issue.
It can also be a bit of a pain getting to the front row of bolts on the sump pan as they are so close to the cross member. None of this cannot be over come.
Whilst you can change the big end shells this way you cannot change the main crank bearings without taking the engine out. So fingers crossed it is the big ends shells.

[fulvia griff]

Cheers for the advice, and sorry about this late reply!

I've decided to take the engine out at christmas when I've got some time as its sounding quite ill now and the oil pressure is best described as terrifyingly low, a full rebuild is on the cards.

[Clousta]

Yes, It can be done.

My trick was to unbolt the engine mounts and jack up the engine (under the sump with padding) and slip in wooden spacers beneath the engine mounts. This makes a gap between the front cross member and bottom of the sump. The front sump bolts are then accessible.

Put cardboard on the garage floor - it can get very cold lying there! I didn't have the space or access to an engine crane hence the work was done in place.