Small end bush replacement.

[SeanM]

Looking to replace the small end bushes on a straight 6, are they a home DIY replacement with the internal diameter being good enough as purchased or do they need to be machined to fit (reamed)? When I inspected I found no.5 had rotated and the oil hole wasn't aligned, could also press out with thumb!

Thanks

[Rob Salisbury]

They need reaming, best to supply the gudgeon pins so they can be matched, machine shop job I'm afraid, the bush should be an interference fit and is pressed in, then the rod is fitted in a jig that keeps the reaming of the small end completely parallel with the bore of the big end journal. When done correctly the pins should be a sliding push fit, and not able to fall through under their own weight. I hope the wear that is allowing your bush to rotate is on the bush, otherwise you may have to change the rod.

Cheers Rob

[RogerH]

Hi Sean,

unless you are geared up to do this sort of thing then it would be advisable to put it out to a work shop.

 

In essence it is not a difficult job but does need some accuracy.

 

Roger

[SeanM]

Many thanks, off to the machine shop it is then.

[BlueTR3A-5EKT]

The new bushes need to be honed in line and on the same (parallel) axis as the Big End or the piston sits cocked in the bore and/or at different deck heights.

 

Cheers

Peter W

[SeanM]

Rob, turns out the rod was at fault, replacement sourced and ready to fit.