Is it possible to replace the crankshaft bearings (main)
Without removing the flywheel etc? I cannot undo the bolts, I do not have access to an impact gun and do not want to round off the bolt heads in attempting to undo them.
If so what is the best method.
Engine has already been removed from the car.
Main bearing change
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Steven collins
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Re: Main bearing change
Hi Steven. It may be possible, but to be honest I have never tried it. I have removed and replaced bearings in situ just to check condition, but that's all.
If you really need to replace them (?) then you will need the crankshaft out for measurement to get the right shell size and probably regrind.
The flywheel bolts have very shallow heads and can be difficult to grip, but they should come out fairly easily. Get a good quality 6 sided socket which will fit flush against the flywheel.
Others may have advice for you,
Ian F
If you really need to replace them (?) then you will need the crankshaft out for measurement to get the right shell size and probably regrind.
The flywheel bolts have very shallow heads and can be difficult to grip, but they should come out fairly easily. Get a good quality 6 sided socket which will fit flush against the flywheel.
Others may have advice for you,
Ian F
MGCC member
1972 BGT, Blaze, Navy trim, recessed grill
1961 Midget, 948cc, Clipper Blue, Blue trim and weather gear
1972 BGT, Blaze, Navy trim, recessed grill
1961 Midget, 948cc, Clipper Blue, Blue trim and weather gear
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Steven collins
- Posts: 126
- Joined: Fri Oct 31, 2014 5:20 am
- Forename: Steve
- Surname: Collins
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- MGOC Member: Yes
- Location: North Essex
Re: Main bearing change
Thanks Ian,
The Bearings I'm led to believe will have an oversize marked on them if different from standard setup but until I remove one of them I will not know what size to order assuming they in fact require changing!! Here’s to holding on to hope that they will be ok.
The big end bearings are standard (lovely copper colour so well worn!!) size.
The Bearings I'm led to believe will have an oversize marked on them if different from standard setup but until I remove one of them I will not know what size to order assuming they in fact require changing!! Here’s to holding on to hope that they will be ok.
The big end bearings are standard (lovely copper colour so well worn!!) size.
Last edited by Steven collins on Sun Mar 22, 2020 10:49 am, edited 1 time in total.
Re: Main bearing change
Hi Steven, yes, you are correct, the bearings will be marked giving their size: std, +100+20 etc.
The difficulty is that knowing the size doesn't inform you of what next size to buy.
Out of round bearings will not be rectified by a new bearing, they will need a grind to the next size. It sounds like your big ends will need a regrind, so I would think your mains might as well.
Not what you want to hear I'm sure, but with the engine out you would be advised to do a thorough job - don't want to be doing it all again anytime soon 😊
Ian F
The difficulty is that knowing the size doesn't inform you of what next size to buy.
Out of round bearings will not be rectified by a new bearing, they will need a grind to the next size. It sounds like your big ends will need a regrind, so I would think your mains might as well.
Not what you want to hear I'm sure, but with the engine out you would be advised to do a thorough job - don't want to be doing it all again anytime soon 😊
Ian F
MGCC member
1972 BGT, Blaze, Navy trim, recessed grill
1961 Midget, 948cc, Clipper Blue, Blue trim and weather gear
1972 BGT, Blaze, Navy trim, recessed grill
1961 Midget, 948cc, Clipper Blue, Blue trim and weather gear
Re: Main bearing change
P.s. that should be +10, I doubt that +100 size is available 😁
Ian F
Ian F
MGCC member
1972 BGT, Blaze, Navy trim, recessed grill
1961 Midget, 948cc, Clipper Blue, Blue trim and weather gear
1972 BGT, Blaze, Navy trim, recessed grill
1961 Midget, 948cc, Clipper Blue, Blue trim and weather gear
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Steven collins
- Posts: 126
- Joined: Fri Oct 31, 2014 5:20 am
- Forename: Steve
- Surname: Collins
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- Location: North Essex
Re: Main bearing change
Haha if it’s +100 required think that would be a new engine on order!!
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Steven collins
- Posts: 126
- Joined: Fri Oct 31, 2014 5:20 am
- Forename: Steve
- Surname: Collins
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- Location: North Essex
Re: Main bearing change
Right.... for love nor money I cannot get the 2 end caps off, the nuts are undone, I found a stubby piece of threaded bar to fit into the middle to help wriggle the cap off all to no avail!!
Is there a tool out there I can purchase to assist or is it just a matter of brute force?
Skinned knuckles are not a pretty sight.....
[attachment=0]84AB2034-C7E9-4FC4-A28D-362D88BC4AA9.jpeg[/attachment]
Is there a tool out there I can purchase to assist or is it just a matter of brute force?
Skinned knuckles are not a pretty sight.....
[attachment=0]84AB2034-C7E9-4FC4-A28D-362D88BC4AA9.jpeg[/attachment]
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Peter Cresswell
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Re: Main bearing change
Hi Steven,
Sorry for coming to your thread a bit late in the day but I have been unravelling the cancellation of our Drive it Day outing and helping resolve our village commemorations for the 75th anniversary of VE Day.
Have you taken off the front and rear steel plates? You have to take these off before you can remove the No 1 and No 5 Main Bearing caps as the front and rear plates bolt into these. This means removing all the timing gear at the front and the clutch and flywheel at the back.
The main bearing caps need a slide hammer to pull them vertically upwards. With the front and rear plates removed it is possible to move the caps for bearing Nos 1 and 5 forwards and backwards until you can get a large screwdriver between the cap and the block to ease them apart, but it is much easier with a slide hammer.
If the Big end bearings are as worn as you say, then the crank will need regrinding, and I would suggest you are guided by the engineering shop as to what they are ground to and let them get the new main and big end shells.
Overhauling the engine yourself will save you some money but perhaps not as much as you think so check out prices for re-conditioned units from many of the suppliers. You might get a good price from Mechspec in Doncaster. See here: http://mechspec.co.uk/enginerange.html. You will find prices further down the page.
Pete
Sorry for coming to your thread a bit late in the day but I have been unravelling the cancellation of our Drive it Day outing and helping resolve our village commemorations for the 75th anniversary of VE Day.
Have you taken off the front and rear steel plates? You have to take these off before you can remove the No 1 and No 5 Main Bearing caps as the front and rear plates bolt into these. This means removing all the timing gear at the front and the clutch and flywheel at the back.
The main bearing caps need a slide hammer to pull them vertically upwards. With the front and rear plates removed it is possible to move the caps for bearing Nos 1 and 5 forwards and backwards until you can get a large screwdriver between the cap and the block to ease them apart, but it is much easier with a slide hammer.
If the Big end bearings are as worn as you say, then the crank will need regrinding, and I would suggest you are guided by the engineering shop as to what they are ground to and let them get the new main and big end shells.
Overhauling the engine yourself will save you some money but perhaps not as much as you think so check out prices for re-conditioned units from many of the suppliers. You might get a good price from Mechspec in Doncaster. See here: http://mechspec.co.uk/enginerange.html. You will find prices further down the page.
Pete
Pete
1969 MGB Roadster
2020 MG HS Exclusive
2007 Mercedes SLK
Plus 34 other cars since 1965
1969 MGB Roadster
2020 MG HS Exclusive
2007 Mercedes SLK
Plus 34 other cars since 1965
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Peter Cresswell
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- Joined: Fri Oct 31, 2014 10:05 am
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Re: Main bearing change
Steven
Forgot to mention, the threaded hole in the centre of the bearing caps is for attaching a slide hammer.
Have you managed to undo the flywheel yet?
Hope this helps!
Pete
Forgot to mention, the threaded hole in the centre of the bearing caps is for attaching a slide hammer.
Have you managed to undo the flywheel yet?
Hope this helps!
Pete
Pete
1969 MGB Roadster
2020 MG HS Exclusive
2007 Mercedes SLK
Plus 34 other cars since 1965
1969 MGB Roadster
2020 MG HS Exclusive
2007 Mercedes SLK
Plus 34 other cars since 1965
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Steven collins
- Posts: 126
- Joined: Fri Oct 31, 2014 5:20 am
- Forename: Steve
- Surname: Collins
- MGCC Member: Yes
- MGOC Member: Yes
- Location: North Essex
Re: Main bearing change
Hi Pete,
Short answer is no I haven’t, must of been a gorilla who did the bolts up certainly more pressure than the torq settings advised.
Long answer....
I have changed all the big end bearings (most were not in too bad a condition and better than I thought they would be, only 1 was showing any copper.
I can access the 3 main bearing caps with no difficulties, these again showing signs of slight wear, however, I do not have a slide hammer (on order which I am told will now not be delivered for the time being!!)
I am getting different comments re 1 and 5 caps some say I can remove them without removing flywheel and timing chains etc others say I have to strip it all down, so a little confused to be honest. I know that the 2 bolts on the timing cover go into the cap ( those I have removed)
Do you know the thread size in the centre of the caps?
Short answer is no I haven’t, must of been a gorilla who did the bolts up certainly more pressure than the torq settings advised.
Long answer....
I have changed all the big end bearings (most were not in too bad a condition and better than I thought they would be, only 1 was showing any copper.
I can access the 3 main bearing caps with no difficulties, these again showing signs of slight wear, however, I do not have a slide hammer (on order which I am told will now not be delivered for the time being!!)
I am getting different comments re 1 and 5 caps some say I can remove them without removing flywheel and timing chains etc others say I have to strip it all down, so a little confused to be honest. I know that the 2 bolts on the timing cover go into the cap ( those I have removed)
Do you know the thread size in the centre of the caps?