knocking noise from 1098

[picky]

Recently the engine has lost power and is making an irregular knocking noise when ticking over. I think this means the big end bearings are worn? But removing the centre main bearing shows this to be badly worn and scratched aswell. I would check the big end bearings aswell but I cant undo the bolts so they are soaking in WD40 and I will have another go later, but Im guessing I need to replace the big end and main bearings? a temporary fix would be really useful, as I am planning to fit a marina unit after my A levels are done...
help much appreciated!!
Tim

[bigginger]

I don't know a temp tip for it (except for sawdust in the oil), but I do know that penetrating oil would be better than WD. It shouldn't need it really, they've been bathed in oil for a long time. They're done up pretty tight though, and held by rataining tabs which need to be knoked flat with a chisel and hammer.

[Packedup]

If the mains are toast you can be sure the big ends are shot too. And if they're that bad then the crank may well be too worn to make it worth dropping new shells on unless you're happy to have them chew up within a few hundred miles (or less).

Some super thick oil might buy a bit more time too.

[bmcecosse]

These bolts have been soaking in oil - there is NO POINT adding release oil now ! If the centre main is damaged there is no point fitting new shells - just a waste of £ 30/40 - they will only last 10 minutes. Only hope is to add really thick oil - and drive it slowly with fingers crossed.

[chrisd87]

and drive it slowly with fingers crossed.

Err... does that mean a badly knocking engine could cease up or break down then? I ask because mine makes a dreadful noise and vibrates badly when unler load above about 50mph, or under acceleration above 3000rpm or so. Oh yes, and I'm driving about 60 miles in it on Monday.

'Stop Smoke' oil added to 20W/50 hasn't helped it either.

[bigginger]

It means it could end life violently and suddenly as a con-rod gives up and heads through the block...

[Packedup]

It means it could end life violently and suddenly as a con-rod gives up and heads through the block...

Yeah, but if the remains don't interfere with teh crank or go through an oilway that's at least driveable.

It's when the end cap goes through the sump and you lose all your oil that you're really stuck, cause an open-vented 3 pot is always going to be a better runner than a totally seized 4... ;)

[chrisd87]

Ouch. Better get a new one quick then!

[bigginger]

It means it could end life violently and suddenly as a con-rod gives up and heads through the block...

Yeah, but if the remains don't interfere with teh crank or go through an oilway that's at least driveable.

Fair point - sounds like you've been there and done that...

[Pyoor_Kate]

Heh, my parents managed to limp up the hard shoulder in our old Mark 2 E-scrote when it decided to fire some part of it's Kent engine out through the side of said engine. I do remember it sounding very sick, and the top speed had dropped from 80* to about 25mph.

I also remember my dad showing me the hole, but can't remember what component had disintegrated and exited at speed.

* Actually the top speed was an alledged end-of-the-speedo, when my mum drove. Don't *any* of you comment on where I get my driving style from.

[picky]

thanks for the advice everyone Im hoping to be able to renew the conrod bearings but I havnt been able to remove the bolts yet, I fitted a new set of bearing shells in the centre bearing as you can replace it without taking the engine out, but when I tighten up the bearing cap bolts the crank is stuck solid and wont move!! When the bolts are slackened then the crank spins ok ( i have the spark plugs out btw) Also having removed the bearings they are already getting scored in the same places as the old ones. So im guessing the crankshaft is no good?? I will put the old bearings back in and hope it still limps along until I sort out new engine...grrrr

[wanderinstar]

Could you possibly be trying to fit, say, std. bearings onto an already reground crank, or would it be impossible to slide the top bearing round the crank?
Ian.

[picky]

Good point, but ive double checked and the old bearings say 020" on them and so do the new ones.. sadly i dont think there is an easy answer.

[bmcecosse]

There is an easy answer - a crank re-grind! The new shells must go in the correct way round - with the 'tabs' correctly located in the block and in the main cap - and the cap must go on with the tab on the cap on the same side as the tab in the block. But - as you have discovered - new shells are a waste of time and money. But are you sure all along that this is the big problem - you say noisey at idle - this would need to be REALLY bad bearings - or is it simply a mis-fire/oiled plug/blown head gasket. You should have the caps off the big-ends - one by one - if they are really bad you should NOT run the engine again. At worst it will blow up on you - at the least it could easily damage the con-rods - and damage the crank so badly it can't be reground.

[picky]

bmcecosse, of course regrinding the crank or replacing it will solve the problem, its just that I would like to keep the car going on this engine if I can for a few months, until I have finished my A levels. In my gap year I will be starting again with a tuned marina unit. The 1098cc engine is still in the car which is why I can only undo the centre main bearing, to remove the front and rear ones the engine has to be taken out of the car. I feel there is no point spending any large amount of time or money on an engine that is about to be removed. Im just going to have to borrow parents cars....

[wanderinstar]

Could this tapping noise at tickover possibly be timing chain rattle. I have a similar noise that goes as you rev engine up. When I get the time I am going to fit a Mini timing chain tensioner that some kind hearted person let me have. Just a thought.
Ian.

[ian-s]

bmcecosse, of course regrinding the crank or replacing it will solve the problem, its just that I would like to keep the car going on this engine if I can for a few months, until I have finished my A levels. In my gap year I will be starting again with a tuned marina unit. The 1098cc engine is still in the car which is why I can only undo the centre main bearing, to remove the front and rear ones the engine has to be taken out of the car. I feel there is no point spending any large amount of time or money on an engine that is about to be removed. Im just going to have to borrow parents cars....

I think you would be wasting any money you spent on this engine apart from doing the job properly and getting the crank reground with all new bearings. As it is ,it could fail totally at any time and leave you stranded miles from anywhere.

[newagetraveller]

A temporary fix for this problem is to pack the shells out with aluminium foil.