Club126UK
Fiat 126 Chat => Tuning & Customising 126 Models => Topic started by: Da Londo on January 17, 2015, 08:12:46 PM
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I have very rusty cylinders, do I need to do something about it?
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No it's fine just give it a rub with a wire brush
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I always wondered what Dave's second name was....
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Tnx Gadge, next question, I removed the cylinders of the top of the pistons, is it possible to get it back on like this? Broke the 3rd piston ring trying to.
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I don't understand? Do you mean is it possible to re-fit the Pistons from the top of the cylinder?
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No, I mean to refit the cylinders over the pistons. From top to bottom. Or do I need to take the whole engine apart so I can use a piston ring tool to fit the pistons in the cylinders and then fit it to the engine.
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when I did my beetle engine I used a motorcycle piston ring compressor it allows you to put barrels on with the pistons in situ like this-
http://www.uktools.com/product_info.php?products_id=606
(http://www.uktools.com/images/js/big/JS-H144.jpg)
(this one is quite expensive but you can get cheaper ones...)
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Ahh I see. It's probably best to remove the Pistons then fit the barrels on then slide the pistons down through the top of the cylinders :) I only say this as this is the way I was taught and you don't want to ruin a piston ring.
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If you don't have a piston ring compressor, use a straight tin can and a jubilee clip ;D
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I actually ordered a piston ring tool yesterday. But I think it's best to take all apart wilst I'm this far.
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Tnx Gadge, next question, I removed the cylinders of the top of the pistons, is it possible to get it back on like this? Broke the 3rd piston ring trying to.
Piston rings are the most delicate items in the whole engine rebuilding process and it can be a bit of a mare when you break one. With the air cooled engines ring compressors work best when you drop the Pistons in from the top. I prefer to lift off the barrels then fit the Pistons from the bottom into the barrels .(http://tapatalk.imageshack.com/v2/15/01/18/175043b15768b6dbf78c18803fc4ea64.jpg)
Do not forget if you are fitting new rings to hone or glaze bust the bores. I tend to push the rings in with a screwdriver into the lead at the base of the barrels as I think this helps to get the 120 degree spacing between the ring gaps.(http://tapatalk.imageshack.com/v2/15/01/18/9401890c6279161e2be538d6748edaec.jpg)
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Do not forget if you are fitting new rings to hone or glaze bust the bores.
Could you explain this? I don't really understand.
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Could you explain this? I don't really understand.
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In a used engine the piston rings bed into the bores to form a close seal. The cylinder wall takes on a fine shine or glaze matched to the piston rings to get the best compression. If you remove the pistons or fit new piston rings then you should break the glaze or shine on the bores to allow a new seal to be formed :)
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Aha! And how do we achieve it? Not with sandpaper obviously.
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Aha! And how do we achieve it? Not with sandpaper obviously.
You are not far off there. You can get bore honing / glaze busting tools on ebay for £20 or less that fit into an electric drill. I made my own from a piece of bar fitted with four small rods. Then slotted in half a sheet of 150 grit wet or dry folded over so it is like double sided. The bar fits into the drill then the wet or dry into the bore. Lubricate with a little white spirit or very light oil then run the drill moving the goner up and down the bore. I have used a piece of wood dowelling before as well instead of the rod then slit it down with a saw .(http://tapatalk.imageshack.com/v2/15/01/19/4e62e5f770a85e62380aca490164640c.jpg)(http://tapatalk.imageshack.com/v2/15/01/19/c9431f3143dd89514dfd063e0bc79448.jpg)(http://tapatalk.imageshack.com/v2/15/01/19/f20f4849639eee0380e5dc6ae1393017.jpg)
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So that woild be a light sanding with 150 grit? I thought that was the worst one could be doing to the bores?
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Only if you don't clean them afterwards ;D Apparently, if rings are proving reluctant to seal after an engine rebuild then introducing powdered Vim via the air intake can work :o I've never tried it myself as the cheap glaze buster I got from Machine Mart has always worked fine (as did the manual method before that).
Keith