Technical BIG END Bearings - Easily repairable??! What are they?? please take a look

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Technical BIG END Bearings - Easily repairable??! What are they?? please take a look

dbriglee

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Hi guys,
Hope eveyone is ok on this lovely day :)
I've got a mk 1 sporting with what has been diagnosed as failed big-end bearings, which makes a loud rattle.
To replace these, as Haynes says, you need to take off the sump, remove the pistons, unscrew big end bearings and remove shells...etcetc..

However, to fix the problem what do I need to replace?? just the big end shells??
I also read somewhere that if the big end bearings are gone, then the main bearings will be gone also....
so if I do the work myself,firstly:
how hard is it?
What do i need to replace? both big end AND main bearing shells?? And if i do replace the shells, do i need to get the crank ground to match the shells?

I have done lots of work before on cars, but never really gone further down than the head gasket :p so all this bottom end of the engine needs understanding :) would be grateful if someone could explain what i need to do.#


Cheers Guys
 

Shunter

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If the big end bearings have actually gone then the crankshaft will have to be reground and new oversize big end, and main bearing shells will have to be fitted along with a set of gaskets.
 

faster4_tec

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^^^^yeah that^^^


it is a fairly big job, the engine CAN remain in the car, but it depends how good you are at working upside down:D , crankshaft needs to be totally removed as do pistons to get the races ground ready for the new shells, cost me £35 for the grinding and polishing, once you have got everything prepped its pretty easy to put back, pistons all ways need to go back in same hole and exactly the same rotation (There are only two so not that hard, just careful prep work and well organised).

Its also a very very ver mucky job, as you get used black oil and gunk and dust off the floor all sticking to you in a disgusting mix of old oil and gunk, and you are bound to get some in your eye too :yum:
 

dave

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midland fiat said:
how on earth can you remove a crank from a engine with it still in place????
remove gearbox clutch, flywheel, put one of them bars that hold engine up in place, remove cam belt exhaust down pipe and sump, tis daft though, be easier to take lump out.

if it is bigends be easier to do what pete says change whole engine.
but it dont sound like big ends to me, they knock not rattle
 
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only an idiot would do that tho, far more work! Not at all a sensible comment!

I have good engines for circa 200 if you find that route easier.
 

Hellcat

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When my parents tipo dumped ALL its oil and siezed, just replacing the shells from the bottom fixed it enough to run for quite a while after until the throttle pot broken (again) and it wasn't worth the nearly £300 cost for replacement.
 
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but an engine dumping its oil and siezing due to lack of lube will be in better state than a "worn" enigne, that will just kill the bearings and maybe just scratch the crank as apposed to wearing it out!

its still easier to swap engines with how cheap they are than messing with bearing swaps!
 

dave

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midland fiat said:
only an idiot would do that tho, far more work! Not at all a sensible comment!

I have good engines for circa 200 if you find that route easier.
wtf you ask for if you didnt want the answer,
 
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no no no not aimed at you chill, no faster4tec, why suggest doing a crank job with the engine in place???

God dave chill ;)

I just dont understand why on earth someone would tell someone to do such a major job in a mess about way, come on it makes no sense and helps no one!
 

dave

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he dont tell him to do it like that, hes trying to put him off doing it like saying about muck in eyes n its upside down job, its haynes that say its an in car job
 

faster4_tec

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cos I did a crank job with the engine still in place, cos my wiring looms a mess, and I don't fancy having to chase up stupid electrical bullpop (mechanical problems = no problem, electrical problems = spawn of satan), but I found I needed a rebore and new pistons, so ended up pulling the block for a rebore and bigger pistons, my engines probably more like 1300cc now:D
 
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dbriglee

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faster4_tec said:
^^^^yeah that^^^


it is a fairly big job, the engine CAN remain in the car, but it depends how good you are at working upside down:D , crankshaft needs to be totally removed as do pistons to get the races ground ready for the new shells, cost me £35 for the grinding and polishing, once you have got everything prepped its pretty easy to put back, pistons all ways need to go back in same hole and exactly the same rotation QUOTE]


cheers guys.
Id need to take the engine in to have the crank matched with the new shells wouldnt I??
 

faster4_tec

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only reason engine would need to go in is to be bored out or honed out a bit.

You can pick up the crank in your hands (just, not that heavy, but FFS don't drop it, it will shatter), and pistons are easily marked up with a tippex pen (That works upside down LOL)
 
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dbriglee

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faster4_tec said:
only reason engine would need to go in is to be bored out or honed out a bit.

You can pick up the crank in your hands (just, not that heavy, but FFS don't drop it, it will shatter), and pistons are easily marked up with a tippex pen (That works upside down LOL)

ok, now i'm very confused.......

I thought that the crank shells need to be replaced and the crank bored to match the new shellls. Therefore, the engineer requires the bearings (where the shells rest on and bolted to the block) and also the crank together.

and what do you mean mark up the pistons?? If they require new piston rings, arent they matched to the cylinder diameter? how would the engineer place know what size to use if he didnt know the diameter of the cylinder??

help :|
 

pubcrawler

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my tuppence worth:

In the past I've only had limited success fitting new big end shells without having the crankshaft reground, even after careful inspection/measurement of the journals. The engines usually knock afterwards. I wouldn't go there now. :yuck:

While you're at it you of course change the main bearings, which add to the expense, then you start to think about the pistons and bores.............

I recon a known good used engine, one you've heard running, would be the best option, you know it's going to be ok. :D
 
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