Big End Bearing Uneven Wear

[lemons]

Hi all,

Would you be able to advise on possible causes for uneven big end bearing shell wear on a 3.5

I had a knock develop under acceleration, after deciding to remove the sump and check the big end bearings no.3 revealed an issue. It is the only big end showing signs of wear on the shells. This cap also shows a strike mark and rub marks on one of the sides.

I'm guessing a side load issue has caused the wear but unsure as to why this would happen. All rods are in the correct orientation (dimples together) and all caps / shell oil spirt holes were aligned.

It looks like the strike mark occurred some time ago but the rub marks appear more recent.

Any help appreciated, thanks.

[ChrisJC]

Possibly an assembly issue?, maybe a bit of muck between shell and cap causing it to be a bit tight? Or maybe crank journal slightly oversize on that one.

Chris.

[stevieturbo]

Bent rod ?

[SimpleSimon]

[lemons]

Thanks for the suggestions,

Decided to put a set of shells in as they weren't mega money, along with some fresh oil. I use the land rover daily so hopefully this will buy me a bit of time before doing the correct fix. The knock is no more but let see for how long!

Oil pressure @35psi hot engine idle, up to around 60 psi 4000rpm.

I couldn't make out any particles under the shells, not to say there wasn't anything at some point however. A slightly bent rod or slightly larger pin diameter a good suggestion also.

Thanks again for the help.

[Mc Tool]

Yup , bent rod , new shells wont fix that. I have heaps of 2nd hand rods , so Im sure someone much closer to you will have a spare too. As long as you get the same type of rod , look at the machined pad just above the big end and get the same rod type .