big end bearings

[kennatt]

your original posting was about a big end (Possibly) knocking have you identified if the big end shells were worn as bm says can you post photos of shells and shaft journals your last post dosn't indicate if the shells were worn.I don't think a slightly scored shaft would cause a knock unless the coresponding shells were worn down to the backing most oldish engines will have some signs of marking on the shaft I've had engines to bits that have had very deep marking,especially B series MGBs,that have not been knocking,Its worn shells and shaft journals which had been worn oval ,that generally are the cause.

[bmcecosse]

Absolutely - although I have to say when I bought my Trav the big ends were 'rattling' on start-up (negotiated £100 off) - due to lack of oil from the previous owner. I filled it before driving it home - and then shortly after pulled the engine and the shells were indeed worn, but no scoring. I checked the crank and all the journals were absolutely spot-on for size and no scoring - new shells and oil pump, and it's run perfectly ever since with 60/70psi at decent revs. So - if caught in time - new shells are a good possibility. the BIG killer is letting the oil level go low, second biggest is missing plate and/or spring in the oil filter casing resulting in completely unfiltered oil circulating.......

[green123]

yes indded it is the shell beasrings which were worn they have gone right back and are going to be changed as with the main bearings so hopefully going to be a good engine once again anybody know what i shoiuld so when i put then back on ie put oil etc on shells cheers

[kennatt]

how many miles have you done since the other shells (Old ones) were fitted just roughly.

[Neil MG]

Check the bearing clearances with "plastigage" or you may find you get to do it all again sooner than you like. Quick, simple and very accurate.

[bmcecosse]

Lashings of good clean oil (don't get suckered in to 'assembly lube') and check the crank spins freely after you nip up each and every bearing........... And be sure to preload the new oil pump with oil - even some vaseline too if you think the engine may stand for some time before you will be starting it......

[linearaudio]

If it were down to plastigauge or a cheap digital vernier caliper, which would be handy over a wide range of measurements, I know which I would go for. You are interested in ovality, so absolute size accuracy becomes less of a concern. Even the cheapest digital vernier will do a reliable, repeatable roundness comparison. My one has packed up, but can still be locked in the larger plane, and the difference measured with feeler gauges in the smaller plane. (Nothing against plastigauge, just thinking of the comparative usefulness of the two measurement systems!)

[Neil MG]

I don't disagree with any of that!

No reason why you can't do both. I know that may seem unnecessary, but the beauty of the plastigage is it will pick up any other problems in installation. Dirt trapped between cap surfaces, previous machining problems, incorrectly marked shells, swapped caps etc. For me it is the fact that it is so quick and easy to use, as well as indicating the actual resulting (as opposed to measured) clearance, that is its appeal.

[kennatt]

Check the bearing clearances with "plastigage" or you may find you get to do it all again sooner than you like. Quick, simple and very accurate.

yes without trying to frighten him this is why I was asking about the milage if low I suspect that the shaft has gone oval and need to be reground

[green123]

i doint know how many miles as i bought the engine of a person who took it out of his car he sed it had done 150,000 miles so about time for a change of bearings it was actually the shell bearings which was rattling but i am changing the main and shell bearings while i am at it so it makes it easier next time thanks for all your help but i hav e another question when i pu tthe bearings in to i put oil on them or do i put something on them i can buy or do i put then in dry if somebody coiuld help me there that would be great cheers

[katy]

Lashings of good clean oil (don't get suckered in to 'assembly lube') and check the crank spins freely after you nip up each and every bearing........... And be sure to preload the new oil pump with oil - even some vaseline too if you think the engine may stand for some time before you will be starting it......

[Alec]

Hello Green123,

"when i pu tthe bearings in to i put oil on them or do i put something on them i can buy or do i put then in dry if somebody coiuld help me there that would be great cheers"

That question was answered earlier:-

"by bmcecosse » Tue Dec 06 2011 4:32 pm
Lashings of good clean oil (don't get suckered in to 'assembly lube') and check the crank spins freely after you nip up each and every bearing........... And be sure to preload the new oil pump with oil - even some vaseline too if you think the engine may stand for some time before you will be starting it......"

Alec

[green123]

ok thanks alot i will do that when they arrive not happy as i ordered them usnday payed 1st class standard from esm spares and still not here

[bmcecosse]

You don't say if you ordered an oil pump - did you ???

[green123]

no i dint order a oil pump i just ordered the bearings at first what happens if i odnt get a oil pump id this important

[bmcecosse]

The pump is likely to be knackered - I would ALWAYS fit a new pump - but it's up to you. Knackered pump + new bearing shells = ruined shells/crank in next to no time.........
Do you have any idea WHY the current bearings were knocking - what caused this ?

[kennatt]

probably by the 150,000,honestly green 123 get the shaft journals checked before you put the shells in or you may well be doing the same job again. I certainly would'nt just put the shells in ,after 150,000 miles I would say the shaft will be oval unless reground already what is on the back of the shell casing std or +a figure

[green123]

hello the shells were std tht came out the shells were worn right down and could see that they needed changing so i am changing them all why i am at it the engine has been done before so i think it will be alright but i have just looked on ebay and saw a old original crankshaft so myte have a go on that 1 if anybody could let me know they think of it that would be great heres the link http://www.ebay.co.uk/itm/Genuine-New-O ... 336f21baf2

[bmcecosse]

" Has Some Slight Surface Rust That Should Clean Off. " -Hahahahahahahahahahahaha

It's going to need a complete regrind ....... It could be for an 803 or an 848 or a 948 or a 1098 - hard to tell. It looks quite sturdy so probably not an 803 - and the big-ends only just overlap the mains - so I think it might be for a 1098. But I've asked the seller if there are any casting marks/numbers to help identify it.
Anyway - no advantage for you! To satisfy kennatt (and he is right to suggest it) - can you not get a digital caliper gauge and measure the journals - each one two measurements at rt angles to each other.

[green123]

hello do i messure the bit where the conrod is attachteched to the cranksgaft .so i messure the crank shaft where the con rod joins i think it will be alright to use but im not shure i will hopefully get a pik up for you soon