(T) Brava 80SX Piston rings

Hi everybody again! I have started a new thread as the problem posted on my last thread has been sorted and this is a different problem.
My car failed its MOT on rear brake binding (easy fix, adjusted handbrake too much) and emmisions. It seems that the car is burning a small amount of oil and the only reading that was ok was the lambda senser (1.019). My mechanic says that as the head gaket had failed and the car over heated some of the rings may have stuck and are not free to move. Now I am not afraid of the work but want to know if I remove the pistons and manage to free the rings with no damage, hone the cylinders can I use the old rings again, or must I buy new ones? Also where is the best place to get some (maybe pistons aswell). The shop4fiat website can only get them from fiat - I have already asked them.

Well you told us what was ok with the emissions but what was wrong with the emissions? Can't expect answers and then keep the data to yourself

Before you do anything else get some FORTE (no other brand!) engine flush, add it to the oil and drive the car for several days as normal. This usually frees the piston rings.

I'm curious. What would high CO on emissions have to do with piston rings?

new rings, don't be tight!
I could not be arsed to strip it, hone it and rebuild it for it to still smoke as it was using old rings in what are effectively new bores, if you are going as far as an engine strip don't cut corners, it will cost you double!!
don't understand how you got to piston rings either really, rather unclear, it could be burning a bit of oil through the valve stem oil seals, especially if it over heated as they would have gone hard, they also go hard with age and no longer "seal" Never actually heard of a piston ring stickng in a working engine, they are usually steel, along with the cylinder walls they can break as they are quite fragile really to side movement if they have broken or stuck they will leave some nice scoring inside the bores, so at a guess you would have to fit oversized rings then anyway once you have honed the scores out, if you have cooked it due to head gasket there is more chance of you shagging the head than the block.

Thanks for your replies. Right the emission details are: 0.82% CO, 409ppm HC. The specs are, according to BOSTON printout, <=0.3% and <200ppm. As for where I got piston rings from, my mechanic said to me after the MOT, that in some cases when a head head gasket fails and the system overheats then the alloy from the piston can start to melt and make the ring stick and also coat itself on the cylinder bores. He actually showed me a piston where this had happened. But I always thought that oil passing the piston rings would be a real blue colour and what is coming out of the exhaust is only very slightly blue almost not noticable but it is always there. I have read in the haynes manual that the ecu is the learning type so I am going to drive it today, I will also get some of the additive mentioned, and see what happens. The battery was off the car for atleast 1 month whilst I had it but the head gasket failed in October09. I did not have the car then. The cylinder bores looked ok to me when I was doing the head work.

That's extremely high HC and CO and nothing to do with piston rings. It's running very rich and you need to find out why. I would check out the lambda sensor readout at tickover if you haven't already done so

I have an 80SX and it runs staggeringly clean emissions

Right then. I probably should have mentioned that there cars' exhaust was ever so slightly coloured but not a norma blue associated with buring oil past rings. Now maybe some of you more experienced people amoungst us will be able to (hopefully) confirm my following thoughts: The car idles perfectly at 800rpm, no jumping, hesitating or anything it is very very stable, I believe that the rings are ok. As the car goes through heatup the exhaust emissions visibly change, ending up with quite alot of very light blue when the temp is at fan switch on levels. Now I put some forte in the oil and watched over the course of 40mins whilst it idled and witnessed the emissions get alot worse. It still ticks over at 800rpm very stable - as before. But now when I rev it the street disappears - much worse now. I will be honest and say that as I did the job myself I did not change the oil seals in the head (I have changed many a head gasket and never done this before with no probs afterwards). Is it more likely to be valve stem oil seals than rings (posts seem to think so). Thanks - look forward to your replies.

I havn't changed valve oil stem seals a few times either with no problem but it doesn't mean it is always the case, I even got away with it on a Ford Escort CVH engine.. anyway!
I think Valve Stem myself, As you said it ticks over at 800rpm fine, if it had piston ring problems it wouldn't be fine as it would be losing cylinder presure past the rings so it's tick over would be quite rough
a usuall sign of valve stems is whilst it ticks over you get virtually nothing out of the exhust but when you rev it a puffs blueish, you see it in cars that smell a bit behind them but when they go to accelerate you see the oil smoke then it kind of goes again to a faint smell - valve stem seals!, perhaps you might have dislodged one putting the valves back in, when you did the head gasket.
OR!
you cooked it, so when you took off the head did you get it skimmed? if not you may have a bent head, which is not quite sealing across and oilway next to a cylinder, this could be weeping oil thus giving you a slight blue haze all the time but not enough to affect the tick over.
I take it when you replaced the gasket the head and block mating faces where spotless with no gouges from the scraper......
Sounds to me as the car warms up the smoke problem get worse, if it is an oil problem you will be able to smell it on your hand from the exhaust, as engine warms oil gets thinner and could possibly be finding its way past the seals into the combustion chamber
Another poster said it is running rich, very rich, perhaps you should check on the Lamda sensor as well just to make sure the smoke you are seeing is blue and not black, to rich a mix will 'wash' the cylinder walls of oil and allow combustion materials down into the sump, presurise the sump and push oil residue through the breathing system, I would have thought you would have spotted a small misfire through through lack of compresion, but maybe not.
Burning oil could make it seem it is running rich - bear that in mind.

Thanks for your reply Thrisey. I did indeed get the head skimmed as it was banana shaped across the shorter dimension. The car was well and truly cooked when the head gasket failed, and the HT leads stuck to the plug bodies so I could not get them off, luckily two of the plugs were loose, but I had to use quite a bit of force on the remaining two once I had got the head extension off. I dont think the problem was due to purely rich mixture as the emissions have never been black, always slightly lightish blue. My mechanic mate says that valve stems normally cause the initial blue burn but then clean up after a few seconds (or minutes if they are really bad) or as you say running with constant throttle and then accelerating, to get the blue puff and then clearing again. My emissions are always of the cloudy type so it's burning the oil all the time. Well normally anyway but if it is really bad then possibly oil all the time. Anyway I have the stem seals and a valve spring compressor so I am going to change them anyway. I am also going to remove the pistons as I have it in bits again at present so I will soon see excatly what is going on. Thanks gain for your reply. MAXIMOKE.

Well, here I am again. I have changed the valve stem oil seals and there were a few that were suspect, got 16 nice new ones on now. I decided to remove the pistons this time as I only had to remove the sump to get them out, and glad I did. All of the oil control rings were cracked hence my problem and correct original diagnosis. Fortunately the bores have not been damaged and I have now re-honed them. Piston rings arrive soon. Looking forward to getting it back together. Cheers for all your help everybody.

Well done, oil control rings where the culprits eh.
well that was a bit of a suprise, not very often you get rings gone like that these days, lucky about the bores though, well caught!