8 replies to this topic

[Eonblue]

I pulled the head off and had this staring back at me from cylinder number one. I can drag a finger nail on the gouges so I assume drill honing is out of the question. Having the block bored was not in the plan, if I leave it what kind of issues will I have? Oil blowby, low compression?

Oh, all the pistons and bore look good other wise. Number 3 and 4 have a bit more carbon on the head but nothing else out of the ordinary.

[Pigeonto]

You're almost certainly setting yourself up for a fall by leaving it but a leakdown and compression test before removing the head would have helped enormously.But you took it off for a reason????The damage is done now so you could try your luck,its just a few gaskets to buy thats all.The problem is that it may have caused some material from the piston above and below the ring grooves to be pushed into the grooves and jamming the ring/s which is no good at all as they cant spring out.
Once you start, its such a big job on minis to strip down that you end up deciding to rebore anyway. I had a single cylinder mower engine in once which had exactly this,the rings were gently teased out and the grooves tidied up,new rings,hone out and the damn thing was as good as new!! 2 stroke whats more and they will not start with low compression. I doubt any one on here will say anything other than rebore. ps I know an engine that was rebored on just one cylinder! that will put the cat amongst the pigeons....but it is no problem still,no reason to be.

[Cooperman]

There is an engineering term for the condition of that cylinder wall - it's bug****d!
You must have the block re-bored with new pistons or it will simply smoke & drink oil.

[Eonblue]

Yeah, proper procedure would've been to perform a compression and leak down test but I didn't see a reason to do so. The engine seemed healthy, no oil consumption or smoking. I'm doing a full suspension overhaul and because I was in the engine baby doing new cones, subframe mounts, water pump, timing chain plus assorted gaskets it made sense to freshen up the head and valves. As well it's been drinking coolant slightly and seemed to be leaking oil from the head so I assumed the gasket was at fault. Looking at it now the gouges might explain why the oil had gotten dark rather quickly.

I don't want to spend a lot of money on the engine but I do want it to run well until I'm in a position to do an engine swap. At a minimum we're looking at a bore over, piston, piston rings and gaskets. While everything is apart it'd be prudent to check the clutch and flywheel, crank bearings, oil pump, plus the 2nd gear syncro has been a bit crunchy...

[bmcecosse]

If you just want a 'runner' - then use it as is. But as others have said - it really should be rebored/new pistons etc But it all costs £££££......

[Fast Ivan]

i'm no expert but my view is if you keep running it you will cause more damage, them there scores have been caused by bits of metal, them bits of metal are running around your engine, could cause alot more damage than the bores and pistons, if it hasn't already. engine out now fella, limit the damage, limit the cost

[valve bounce]

mine had a similar problem at one time, if you need it to run without a rebore and strip down then get some 180grit wet and dry and use some wd40 and smooth them out, this is what i did in mine cause i was desperate and skint. it worked ok it used less oil that before and went ok but as i said i was desperate so i was happy so long as it ran

but if you have the time and money, engine out, strip down, rebore rebuild, good as new

[valve bounce]

now i think about it, i think i put the piston to dbc and stuck a glaze buster in the bore. not ideal but needs must some times

Edited by valve bounce, 14 September 2012 - 07:30 PM.

[Eonblue]

I think I'll have to bite the bullet and pull the engine out. At the very least I can verify that there's nothing left floating around inside the engine and take it from there. Thanks everyone!

Edit:

Actually would it be worth it to have a good condition used block swapped in or even getting an engine shipped over from the UK? The machine work cost and internal parts alone could probably get me two 998 engines no?

Edited by Eonblue, 14 September 2012 - 08:49 PM.