can someone explain the steps to deglazing/ honing a cylinder bore please.
OOooo was wondering this myself.
Remembers to check Receive Email Notifiations....
Step 1 - Buy honing tool
Step 2 - Set tool for bore size if required
Step 3 - Select suitable drill and set speed nice and slow, mount honing tool
Step 4 - Slide tool into cylinder bore and start the drill, nice and slow. Work the tool up and down the bore fairly quickly without twisting it.
Your aim is to get an even, matt, cross hatched type appearance over the whole length of the cylinder walls.
Engine needs to be totally stripped before you start as well. Otherwise you will end up with bits of metal and grit everywhere.
There are several types of honing tool available, from ones with 3 stones on legs, to ones which look like flap wheels. All will work.
cheers dave, legend as usual!
A brand new piston ring will only actually touch the bore in 3 or 4 places around its circumfrence.
The piston rings need a slightly rough surface so they wear (bed) in to exactly fit the curvature of the bore.
The rough surface texture also allows the cylinder wall to retain an oil film which is vital to prevent hot spots forming on the piston rings during
running in.
If the piston ring locally over heats it looses its spring tension and won't be held against the bore to form the initial seal.
Although gas pressure behind and on top of the ring is what actually push the ring out to form the seal, it is vital there is enough spring tension in
the ring to allow the pressure to build.
With a worn bore thre is the added problem of the top piston ring hitting the wear ridge made by the old ring at the top of the bore, so the wear
ridge should be honed smooth before fitting new rings.
You're looking for between 30 and 45 deg angle on the honing marks
That cant be easy to master !!!
http://www.youtube.com/watch?v=82OMO1ArSkk&NR=1
quote:
Originally posted by britishtrident
A brand new piston ring will only actually touch the bore in 3 or 4 places around its circumfrence.
The piston rings need a slightly rough surface so they wear (bed) in to exactly fit the curvature of the bore.
The rough surface texture also allows the cylinder wall to retain an oil film which is vital to prevent hot spots forming on the piston rings during running in.
If the piston ring locally over heats it looses its spring tension and won't be held against the bore to form the initial seal.
Although gas pressure behind and on top of the ring is what actually push the ring out to form the seal, it is vital there is enough spring tension in the ring to allow the pressure to build.
With a worn bore thre is the added problem of the top piston ring hitting the wear ridge made by the old ring at the top of the bore, so the wear ridge should be honed smooth before fitting new rings.
http://www.youtube.com/watch?v=ZOAdIQsWoPM&NR=1&feature=fvwp
Rebuild a zetec in one minute!
As an apprentice I was taught to oil pistons, rings etc on assembly but it seems that may have been the wrong approach? I remember reading, possibly in the old CCC magazine assembly just using WD40 on the pistons allows to rings to bed in better. When I rebuilt the engine in my car I did try this method and can say I'm pleased with the engine BUT if you try this don't blame me. Also seem to remember race gearboxes being run in filled with Brasso to bed in the gears before final rebuild?
When I was a marine apprentice with BP I worked for a few months in the long gone Isle of Grain oil refinery. After overhauling big gas compressors
they added a self destroying bedding in compound to the oil, the idea was the bedding in compound disappeared to nothing after a few hours running
and you didn't even have to change the oil . Although it looked like sulpher powder and looked like Brasso when you mixed with oil to add to the
sump it was very special stuff and imported specially from the USA.
The Brasso in the rear axle trick was an old Colin Chapman dodge learned from his secondhand car dealing days, it fixes final drive noise due gear
problems but ruins the bearings.
[Edited on 20/9/09 by britishtrident]
Found this
http://www.bunkering.co.kr/bp/products/H15_BP_RUNNING_IN_COMPOUND.htm
^^^ wot the monkey said.
you are aiming to cross hatch the bore, around 45 degrees or a bit less ot the horizontal.
old skool honing is done by hand using 600 wet'n'dry and will work just as well s the cheap DIY honing tools.
and that is fine on loose tolerance engine, oi.e. old ones such as pinto, crossflow .
modern engines are built to much tighter tolerances e.g zetec and the honing is to two stage process - the second one smoots of the bumps left by the
coarser first stage and is probably harder to replicate at hone. (<--- geddit?).
googl will provide you with more info. as well as any correctrions to the above.
quote:
Originally posted by britishtrident
The Brasso in the rear axle trick was an old Colin Chapman dodge learned from his secondhand car dealing days, it fixes final drive noise due gear problems but ruins the bearings.
[Edited on 20/9/09 by britishtrident]
600 grade is much too fine it will polish the bore --- to get the rings to bed in the bore has to be surprisingly rough 120 grade Emmery is nearer the mark.