I have never had an issue doing it but fair enough, everyone has their own habits and reasons for them.
i cant see how? i can understand not cleaning the edges as the carbon helps with compression(at full thrust only).but at the end of the day you have rings and oil scrapers..... if they can do theyre job properly then you wont burn oil? edit:sounded like a tw^t Edited by: riley
More material on the piston face increases compression ratio and hence more power?!?! My mechanic friend (been building engines for years - mostly vauxhall stuff) told me to scrape the piston faces clean when I did mine. Can't say I noticed a difference though...
sorry m8,i didnt put that very well.edited my previous post. just clarifying that the rings and scrapers are there for good reason,to make sure you dont burn oil. why the hell do i keep stating the obvious? Edited by: riley
Make sure the bolt holes are clean now and have no water in, if there is any rust in the threads the bolt will feel tighter when you come to fit the head and will not always give you the correct torque, the resistance on the bolt should be from the compression of the gasket through the tightening of the bolt not from the resistance of the bolt on rusty threads. Run an old bolt down the bolt hole until it hits the bottom (by hand) and then wipe away any water from around the top of the block before removing the bolt, make sure they are all free and the new bolts are lightly oiled or have a little copper slip on before fitting. As GVK says dont clean the tops of the pistons just turn the engine over by hand and wipe the bores as the rings bring any water or carbon up the bore wall. And remember the most important thing when building engines is cleanliness
I was told what GVK was by every one I have spoken to in the motor trade, dont scrape the pistons or it'll COST YOU! I only clean up pistons if they are out of the block. If the car is not going anywhere for a day then you could whip the pistons out, clean them right up fit new big ends, rings and de-glaze the bores while you're at it. Wont take long and you know its good then!
So if you don`t clean them then they are supplied new with a carbon deposit? A new engine is 100% carbon free and doesn`t burn oil does it? I cleaned my piston crowns when they were out of engine and I suppose that when they are in situ then crap could go down the side but I haven`t had any bother for doing so.Personal preference I guess and if you were doing a head gasket job for a customer then going to the bother of cleaning would be a waste of your time. Edited by: DAVE 2227
the only reason i can see not to clean the piston top is the risk of scraping the bore - i can see the logic in the trade, you aint gonna see any benefit from it so why take the risk? but if its your own, the risk of scrapin the bore is nearly zero if you put it at tdc to clean it, then its nice and flush and easier to clean as well. as long as care is taken to remove the bits before reassembly - whats the problem? i scraped all the carbon off me nova when i did that (first car i had ) with the pistons at tdc - it didnt use oil after and i couldnt really scrape the bore the way i did it mike
A new engine will have minimal tolerance between the pistons/bores An old engine won't and it builds up a 'carbon seal' which if you disturb this *can* result in high oil consumption. However,If you've polished your pistons and had no problems, then all well and good
You won't disturb any carbon seal between the rings and bores by cleaning the tops though - I always do mine, just because I like my engines clean inside. If you do it, bring each piston to TDC before you clean it, fill the gaps 'tween piston and bore with grease to catch any bitty bits, then take any loose crap off the top. Wind the piston down and the grease will stay at the top, with any nasty bits that came off. Up to you, though - unless they're REALLY cokey, it's not going to make an enormous difference to anything whether you clean them or not....
I think a bit of folklore is creeping in here........my dad used to do.....such and such! Common sense tells me that the bores will not be damaged by careful scraping or say rotary wire brushing of the caps providing you don't accidentally score the bore with a sharp object. Any miniscule thickness of wall 'ground' away would be easily taken up by the piston ring - not a scratch of course, this might cause a little blow-by, but as I said you have to be careful. I find it hard to believe that carefully removing carbon would cause smoking whatever Mr Car maintenance tutor said!
But they come up so shiney .... From the Marshall Plan Website. Just a brass wire brushing. Dunno whether it's a good/bad idea but certainly looks good, tho as a mechanic mate of mine used to say "What are you gonna do, drive it or put it in a display case?" Joe
So when youve carefully removed the carbon with your rotary wire brush how then are you going to remove the debris that has dropped down the side of the piston into the ring land not to mention the pieces of wire that the wire brush has shed. Debris wont just sit on the top of the rings it will also collect behind the rings. Common sense should tell you that if there is no benefit from removing the carbon then why risk causing any problems.......or it should do
Personally I wouldn't put a wire brush near a piston crown. And I ALWAYS grease round the piston/bore gaps to stop anything getting down there. Up to you though, do it if you want or leave them as they are! It's not going to give you an extra 30hp at the end of the day.....
mmm! - well I'll get the Hoover to the cylinders first of course - I didn't consider crap gettin' in the ring 'land' though - do you mean the 2 spaces between the 2 rings? Presumably a little oil will pass through / around the spaces and help remove any carbon / bits of wire? Will a few bits of wire really do significant damage to the bore? I'm not trying to be clever, I am prepared to admit I'm not always right, just having a debate that's all.
