Changing Main Bearings

Thanks Harvey,

You explain it very well, I understand the purpose, and of course why my clearances would be greater than a newly overhauled engine.

I'll make sure the engine turns over nicely by hand after each bearing is done.

I've also ordered some Graphogen - thanks for the tip!

I've always wondered if , when you are bolting down bearing caps , ,the mating faces should be oil -free to prevent movement or does it get squeezed out . I realise you have to oil the shells


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I always keep them oil free with a quick wipe from a rag. I'm sure any excess oil would be squeezed out, but as there's no reason for those surfaces to be oiled in the first place why take the chance.


Active Member
Brian-Northampton said:
I just wanted to add to this conundrum, the well know bit about the change to the 4 cyl head gasket. To quote from the workshop manual:

From engines with serial suffix letter 'G' onwards the cylinder block has been reduced in height by .013 in. to suit a new steel and asbestos cylinder head gasket.
The cylinder blocks can be identified by the cast boss situated on the cylinder block adjacent to the auxiliary drive sealing plug.
j_radcliffe said:
Taylor's book does not yield any useful information about the suffix. However if you have a TC with an engine number starting 400, 401, or 405 then the block you have was originally an SC block. If your engine number starts 415 then it is TC 10:1 CR, and if it is 416 then it is 9:1. Mine is 10:1 with a 5 stamped over a 6!

I am totally confused RE these engine numbers.... My engine number is 49109684A. The car is a '75 2200TC with 9:1 CR stamped on the cast boss. Although I have no way of knowing if the engine is original, I assume the fact that it has a boss, is stamped 9:1 and is a 2200 must mean it is a late 2200SC/TC block?? Does anyone know what the 491 prefix means please?
Well guys,

Tomorrow is the big day. To be prepared and not waste time when we start, Vanessa (Hermione149 thought it suited her, I kind of agree) has had the oil drained, spark plugs and fan belt removed. She's been jacked up and supported on ramps, with axle stands just behind as the 'belt and braces'

BigMoose (Dave) is coming over for 09:30 in the morning, Colin (next door neighbour) wants to pop over as well. None of us has any experience but bags of willing spirit. At least one things for sure, with 3 of us, there'll be plenty of tea!! :wink:

So keep your fingers crossed, digital camera is at the ready.

and thanks Harvey - hope I don't need to phone!

Not wanting to make any foolish assumptions about engine numbers, I will just add that my 68 10:1 2000TC is Engine # 85900395B... And yes, I used the later gasket.
Hi all,

Yes, all done, and I believe very successfully too!

I say believe, because I just need to tidy up, lower her down to the ground and fill her up with oil!

That will be tomorrow morning, but will be later in the week before I go for a test drive.

I'll get a write up done, as there are a few lessons I learned along the way, but it was pretty much exactly how Harvey described it.

I confess I did ring Harvey 3 times - but there's no shame in that.
First - to make sure I didn't do any thing stupid about getting main bearing cap No 5 off - different to the others.
Second - to talk over main bearing No1 over the crank, which was being a bi@tch. Harvey had some great ideas.
Third - to shout Yahoo! for doing the lot!

Cheers Harvy - thanks.

I'll get the write up/photos on soon!

First signs are looking good.

I gave her a few cranks on the starter to get the oil flowing through the galleys, pulled the choke, and ..................... she's running like a sewing machine :D
and I've got a grin from ear to ear!

Test drive will be one day next week, which is the only way to find out if the oil pressure is now where it should be on idle with very hot oil.



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Well done Brian!

I think that you will be happy on the test drive too.
Just a word of caution though. I think that it would be better to treat her gently for the first thousant miles or so. I know it is not a new engine, with a more or less worn crank and nowhere near as tight as a brand new or fully rebuilt engine, but i feel that it would be better to let the new bearings bed in without asking too much of them.


Richard - My "before" oil pressure readings were a good constant 60 PSI (judging by the dashboard guage), but once the oil was very hot after about 15 minutes of driving (say), then when the car was idling, the oil pressure dropped to 30-40 PSI. Rev the engine and the oil pressure temporarily rose.
We've been out to the In-Laws today, so was unable to go for a test drive. I'll be out one day this week and will let you know if there are any changes (there should be!)

Demetris - thanks for the advice, I had thought I'd take it easy on the old girl for some time to let everything bed in. Out of interest, what did you consider as "running in conditions" when you first started running in your rebuilt engine?? I think I read somewhere that 60MPH was about right. I'd rather think in terms of revs - so that would be about 3000 RPM max for the initial period.



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Hi Brian, it's no black art, just what they advice on contemporary drivers' handbooks.
Do not rev the engine beyond 3000 rpm (about 60 mph in top for the 4 pot) in any gear, do not accelerate hard and do not allow the engine to engine to pink or labour at very low revs in any gear for the first 500 miles. Then you gradualy increase maximum speeds until you can make use of the full performance potential at 2-3 thousant miles. Make sure that you change the oil and filter at least twice within this period. This is what i did and after almost 10K miles there's practically very little oil consumption, minimal blow by and the engine is smooth and silent (for a Rover 4 pot that is...).
However in your case there's no need to follow up all this. I did it because i had to bed in tight bearings and piston rings/bores. There' s no comparison.

As for your "before" oil pressure i think that it was already good enough, and you should not expect huge improvements. I have a capillary oil pressure / temperature gauge fitted and my rebuilt engine will reach 60 PSI from 2000 upwards hot or cold. Idle speed pressure is 45 /50 PSI hot / cold.
My old very engine with very worn rings / bores was not that much worse. Initially i was puzzled because my A series runs at 80 PSI at speed, but i guess it is only fair to compare like with like.
Hi Demetris,

I have a capillary oil pressure / temperature gauge fitted and my rebuilt engine will reach 60 PSI from 2000 upwards hot or cold. Idle speed pressure is 45 /50 PSI hot / cold.
That's the point I think. You get the same idle oil pressure hot or cold. I was getting 60PSI cold and 30-40 PSI hot.
I know that my figures are probably inaccurate and yours will be more accurate with the type of gauge you have, I'm guessing mine by the position of the needle and the only reference point being the 50 in the middle!

I want the same oil pressure hot or cold.

Cheers for the info - I'll keep the revs below 3000 for a while.

Hi all,

I promised I'd do a write up, and I've got my photos in order and picked the bettter ones. This is how Dave (Bigmoose) and I did the job.

1. Remove spark plugs - to make turning the engine over by hand easier
2. Remove Fan Belt - to take the strain off the crankshaft
3. Drain oil
4. Pop to the shops and buy some lollies and Graphogen
5. put the car up on ramps.
6. Follow Workshop manual (1967 version) Page 32A, Operation A1-13 - Sump and internal oil filter remove and refit.

I did the Big Ends in order, so ....
Turn the crank by hand using the crankshaft pulley until number 1 big end is at about 4 O'Clock to give room to access the top shell.

Undo the nuts on the Big End and remove

from the picture - slide the bearing shell out from the left hand side - the side without the 'notch' or 'lug' so that the lug comes out first. Then put the new shell in, in the same way that the old one came out. Plain end first starting on the 'notch' side so that the 'lug' goes in last and sits in the notch.

Then do the top shell. push the big end off the crank and lift over the top of the crank to the other side - that's why I said set it at 4 O'clock to give you room, and repeat the same remove / replace procedure of the shell - and smother it in Graphogen.

Then put both parts of the big end back, replace the nuts and torque up to 30Lb ft.

Repeat for the other 3 Big Ends.

Now start on the Mains
If you look at the main bearing caps, they are all numbered (you can just see it on the first photo), and all have an arrow pointing to the front of the engine. They are also sitting on lugs to prevent them being put on the wrong way round.

I removed all main bearing caps, these are pretty tight.
Main cap number 5 is different to the others, it also holds the rubber semi-circular sump seal, which you could replace, and underneath it is the rear crank lip seal. This one was stiff and needed tapping with a rubber mallet to free it up.

Next release the tension off the bottom chain - I forgot to do this and had trouble with my No 1 bearing!!

Give the crank a little wiggle, not a lot!!, don't go swinging on it!

I started from bearing 5 and worked my way down to No.1

Using Harvey's "patented" special tool, insert the lolly stick on the other side of the bearing to the lug/notch and push/tap the bearing in. When you have about 5mm or so, it's possible to get a grip on the lug with your fingers and pull the bearing all the way round until it is sitting underneath the crank, you can then just lift it off!
This is Main 5 - hence the orange rear crank lip seal.

Next oil the new bearing (don't use graphogen on this one) and put it on the bottom of the crank with the plain end next to the notch and slide the bearing, slide it round the crank until the lug sits in the notch.
This one is the centre bearing - No.3

Repeat for all main bearings.
I had trouble with No.1. First I forgot to release the bottom chain tensioner which was preventing the crank from dropping, then it was still stiff, so Harvey suggested we turn the crank by hand (gently because it's the wrong way) to help twist out the bearing. That worked. However, after we got it out, it was obvious why it was stiff. The chain is still pulling on the crank, and pulling it towards the off-side, so Dave pushed the crank towards the near-side and the new bearing slipped in nice and easy just like the others.
We replaced the bottom bearings, smothered them in Graphogen and replaced them. These torque up to 65Lb ft.

All done!
Now put it all back together.
Don't forget to replace the Internal Oil Filter 'O' ring gasket with a new one.
Don't forget to put the tensioner back onto the lower chain
Don't forget to replace the rear sump oil seal on main No 5 bearing cap.

When you refit the sump, apply liquid gasket all around and do up all the bolts (26 of them) loosly - you need to refit the two bellhousing/sump bolts and torque them up to 25Lb ft first to ensure that the sump is pulled in nice and tight to the bellhousing/gearbox before you tighten them all up.

Here are my old Big End Bearings:

The worst one being Number 4

Here are my old Main Bearings:

The worst one being Number 3

And that's after 65,996 miles!

It is a straight forward job. Dave and I completed the job in 6-7 hours, and that included a lunch break and lots of prodding 'umm'ing and 'aah'ing and of course lots of Rover talk. We did the job very slowly, very methodically, but I believe we've done it right.

I'm still waiting for this damn weather to stop raining so that I can have a proper test drive :roll:

If anyone wants to say "Well Done" then Dave and I will gladly accept, but all praise for a couple of amateurs doing a job like this goes to Harvey.

Thank You Harvey



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No problem!

The ends don't look too bad, but the mains were definately worth changing.

Taking a slow and methodical approach has ensured a good outcome, although I would have had a look at the bottom tensioner at the same time, which is why I never have problems with the front main, because I always back the tensioner off, as most of the time the jangly bottom chain is the reason for doing the job in the first place. But as that was pretty much your only problem you can count the whole operation as a real success. Well done.


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V8's are a bit harder because you have twice as many big ends to do, and also the front main is a bit above the crossmember which makes it more difficult to slide the top shell over, but it is do-able as I've done loads, for various reasons, such as low (er) oil pressure and leaking rope rear main seals, as well as rumbles.

"S" models are easier than Autos because you don't have to drop the exhaust front pipes.