Piston question

[BI8759]

I'm stripping down my 1098 engine that burns oil like it costs nothing. I've taken one piston out and had a look at it: it is badly scored as if it's been scraped down a brick wall!

Would the smoking and the scored pistons be related? The bore has some very faint vertical lines that I'm sure would sand out.

Also, I can't see any marks on the piston so am not sure how to tell what size it is.

Many thanks for any advice

[BI8759]

Looking at it properly, there is a lot of scoring on one side and about half as much directly opposite. On the side that is lightly scored there is a fair bit of piston crown damage that I assume is caused by pinking. On opposite side of the crown is a smaller amount of crown damage. Hope that makes sense.

[brucek]

Best if you can post a picture - the wise heads will know what to do

[MarkyB]

It sounds like rebore and new pistons even without a picture.

[chesney]

Possibly a circlip has disintegrated and has been trapped between the piston/cylinder?

[bmcecosse]

Rebore and new pistons........ Anything else will just be a waste of money.

[MarkyB]

Depending on your priorities, a "known good" engine will probably take less time and money.
You can always rebuild this one at your leisure then.

[BI8759]

Thanks for the good news Does anyone have a ballpark figure for a rebore or a recommended machine shop (I'm in Hampshire).

I'm a bit wary of buying another engine as I've already done that once and it was a dog.

[moggiethouable]

Rebore and new pistons........ Anything else will just be a waste of money.

Bmc, is it fair to say if you cant feel the scratches in the bores then they are salvageable?
Also, I believe the rings are in contact with the bores, I wondered about the pistons being scratched? down the sides presumably?
So would a hone out and new rings be possible?

[bmcecosse]

Depends on the scratches and if there is a lip at top of bore. The description of the pistons suggests at least a partial seizure at some point. If the pistons are ok (but there is talk of top dmage ??) then a set of rings 'may' do the job. But rings are not cheap - best option is to do it right and rebore.

[BI8759]

I've been quoted £120 for a rebore, which is a lot cheaper than ESM's recon block even though I'll need new pistons (which I guess I do anyway). At least I won't need to worry about that for a while.

[BI8759]

Some photos with taken with my shaky hands

[frame][/frame][frame][/frame]

[moggiethouable]

Wow!
New pistons then.

[BI8759]

Looks like the other pistons are fine. I've noticed that the top ring on this one has closed and it is tight around the piston. Does any one know the cause of that please? I'm always this curious with tradesmen, too - what's this? why are you doing that?

[bmcecosse]

£120 for a rebore - does it include new pistons???? That piston is ruined - looks like something solid has been ingested - is the head chamber similarly damaged?? The damage has crumpled the piston top down onto the top ring - hence it is tight. But if the other pistons are ok - and the bores not too bad - you may get away with just a single piston for that bore. Look at the other pistons - is there any sign of an 010 or 020 etc mark on them - or perhaps STD which would indicate standard... Maybe someone on here can sell you a single piston removed from another engine. I stress - none of this is ideal - but when cash is tight - it could keep you going for a while !!

[smithskids]

I have some part used 1098 pistons std bore. You can have one for the cost of postage if its any good. Regards smithskids.

[bmcecosse]

That's a great offer! Could be worth considering. Any chance of pictures of the bores and the 'good' pistons from the damaged engine..

[BI8759]

I thought £120 was reasonable in view of the fact that the only other company who gave me a quote wanted £145 + £220 if I wanted pistons as well. I can only go on the info I have available.

There is a lip at the top of the bore and quite a nasty scratch is the cylinder so I think I will get it rebored but @smithskids - thank you for your very kind offer.

Here's the piston next to the offending one. It's typical of the other two. Some *very* light marks on the skirt but the crown is unmarked apart from some carbon deposits. I think the flash may have highlighted the scores. It's not really that red/brown colour either. Both circlips are still in place.

There are no markings that I can see so I assume the bore is STD. The engine doesn't look like it's been worked on to me (not that I would know) but the big ends are std, the oil pump looks original, nothing looks any newer than the rest of it.

It's all getting a bit pricey, really; if you're not a regular mechanic the cost of parts and tools soon mounts up. Hopefully, the wife won't find out.[frame][/frame][frame][/frame]

[bmcecosse]

Reboring used to be £10 per bore not so long ago - so £40 or so. And then the new pistons of course. If there is a lip on the bore, with the scores - it does need reboring. And if doing that - would be as well to fit an exchange crank and new oil pump to make a 'new' half engine.

[BI8759]

Thanks for the advice, Roy. The crank journals are cutting up a bit where the bearings' oil channels block are so I think this is sound advice. Still works out cheaper than ESM's recon block and I can do it in stages as and when the cash becomes available.