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Discussion Starter #1
I took the rear main bearing cap out today to replace the oil seal and reseal the cap itself as there was some oil in the clutch bell housing when I split the gearbox. I found the following when I removed it which was not what I was expecting. It is a long time ago that I had a main bearing to look at but my recollection was that if they were worn out you can see a copper backing plate through the white metal. If I gently scrape the dark area with my finger nail it does show white metal underneath but is this normal? Haven't taken the other caps off to examine them yet but can easily do so. May be clutching at straws here as my inclination would be to change them all anyway (and big ends if similar) but don't want to do this unnecessarily. The crank journal looks fine by eye. Any advice much appreciated. The current mileage is ca. 70K
 

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no expert and really no idea, I would have imagined them to be super smooth with no obvious signs of wear. yours do look like there is wear on shells

I am in a worse position mine has done 138k wonder what mine look like
 

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Discussion Starter #3
Thanks Brad. I have taken the shell out of the cap now and it seems there may be an imperfection in the cap surface at the points where the wear in the bearing has occurred so it may be a foreign body of some sort trapped between the cap and the shell when it was assembled. I will take a look at the others and big ends with a view to replacing them all. Starting to wonder when this job will stop now! Hopefully won't need doing again in a long time.
 

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Hi,
Did the same job on mine (oil leak on seal) which was at around 130K. The bearing shell was considerably less marked than yours and the journals looked good so popped it back in place. It's not too onerous to drop the sump and swap them out - you're most of the way there as the sump is already off. I'd swap them... though I'm not sure how easy they are to replace at the other end of the crank (at the belt end) with everything in place.
Years ago I had on old Montego that suffered low oil pressure @ idle when warm. The sump was full of swarf from the factory (a standard option I believe) and the shells looked like ploughed fields. As it was an old worthless motor I just swapped them and got a few more years out of the car.
Good luck!
 

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Discussion Starter #6
Any mods on the engine, lighter pulley or flywheel? Overheated engine in the past?
Hi Alan,

The vehicle was a completely standard, one owner vehicle when I bought it 4 years ago. I only drove it for a few hundred miles when I first had it before starting to work on the suspension and it has not made it back onto the road since. The vehicle does seemed to have been reasonably well maintained but this tailed off before I bought it as for the last few years it was only covering around 1000 miles a year. The clutch plate was showing some signs of oil contamination and I suspect the DMF may not have been functioning properly but would that have caused the problem? I think the real test will be when I get the other MB caps off and the big ends. If they are all bad too then suggests an oil problem I would have thought.

Jimmy - thanks for your comments too. Hopefully not in Montego country! Can't be many of them left on the road.
 

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You probably wouldn't have driven the vehicle long enough in that case to determine the oil consumption but it may have been run low briefly at some point. I doubt that the clutch issues would have caused the damage. Keep us updated - like I said I think this is a future job for mine!
 

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Discussion Starter #8
You probably wouldn't have driven the vehicle long enough in that case to determine the oil consumption but it may have been run low briefly at some point. I doubt that the clutch issues would have caused the damage. Keep us updated - like I said I think this is a future job for mine!
Actually managed to get them all off today. Lots of questions I am afraid. Anyone experienced with bearings? Is this as bad as it looks? Is this likely to be oil starvation. Any thoughts on whether I need to get the crank re-ground?
 

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I've seen far worse. I'd say that they were slightly heavily worn for the mileage and that it may have had oil starvation at some point but not chronically so. I agree with the above get a reputable machine shop to inspect and measure the journals - if they can unplug the oil galleries and give it a proper internal clean too they may as well while they've got it. It's likely that it will be fine.

I'd recommend Ivor Searle in Ely Cambs - but that's a bit of a trek for you.
 

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Discussion Starter #11
Thanks Jimmy and HF. Travelling at the moment so only just seen these responses so sorry for the delay. Quite reassuring overall and the Mahle document is a great find. Tried without success to find the same thing. Will keep everyone up to date with outcome.
 

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Discussion Starter #12 (Edited)
Update on progress. I took the crank to Walter Bates in Nottingham on the recommendation of a couple of friends. Amazing Aladdin's Cave of a place basically at the back of his house at Mapperley Top. He measured the journals and pronounced them within spec, so just gave them a polish for £36. Which I thought was fair. I have ordered new main and big end shells (Glyco seem to be the only manufacturer) which I ordered from buycarparts.co.uk (who also go under a myriad of other names but are based in Berlin) at a cost of £82.50 incl delivery for both. Shame they won't arrive until Monday it would have been a perfect weekend to put it back in. Also purchased some assembly lube from Bates which is what they use all the time. No point in risking damage to the bearings on start up especially as it might be some time before it is running again. Only other thing I struggled to find was the front crank cover plate gasket which is on its way from Poland. Edit he said the mains were not too bad for the mileage but big ends would have started to cause problems before long.
 

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