To Hone or not to Hone

[JB5]

Hi Guys,

This may be a simple question and just want your guidance. I have this b6 1.8t quattro in my possession that suffered a head gasket issue. Problem happened on cylinder 2 wall and it's evident due to the big water stain, all the other cylinder walls look perfect. the surface does not feel rough, feels the same as the other cylinder walls, there's no score or scratch. here are my questions:
- Can I do a replacement head gasket and leave cylinder as it is?
- clean the area but not rough it up? like using a super high grit sandpaper with oil and just move the piston all the way down
- if above is not possible, do i need to hone every cylinder or could I hone just the affected one without causing a catastrophic problem?

I'm already replacing the cylinder head since it was cracked on cylinder 2 and I'm not going to be adding more power or anything of the like. Car is staying stock with k03s and no chip, it's an economy daily driver.

Thanks for the help :)

[blitz2190]

do not use sand paper as it will ruin the cross hatch. if the cylinder looks good you could try a soft brush or cloth and some wd-40 or a small amount of brake cleaner on the rag not sprayed into the cylinder.

[JB5]

Thanks Blitz,
Here's a picture of what it looks like



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[BARRY]

problem is you may have an ovaled or elongated cylinder bore. if you do, you might burn oil.

as far as touching your cylinder bores, you should never unless you plan to rebuild the motor. generally speaking if the visual damage cannot catch a fingernail, or can be felt you should be OK.

[JB5]

Thanks Barry, my fingernail really doesn't catch on anything and when rotating the crank it all feels normal, nothing strange.


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[blitz2190]

Thanks Blitz,
Here's a picture of what it looks like



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thats easy to clean with a soft rage and some brake clean, then wipe with wd-40 to prevent rust, but it will burn off the first time you run it with a good head and gasket, so you don't really have to worry unless like barry said the bore is out of round.

[JB5]

Thanks so much guys, this is really why I love Audizine great guidance and help.

[Jet08]

Always good to check both the block and head are flat before replacing the head gasket and also with the replacement head if not new check for cracks around the valves.

[Kevin C]

I have used 600 and 1000 grit paper to take deposits off and to clean up bores. It's not about removing material as much as it is about taking junk off to see what the bore really looks like. One thing I do is to follow the angle of the cross hatch. Less is more.... Just enough to clean the surface. Afterward you need to do a good job of cleaning the bore with WD 40 and a cloth. I have even done it on compressors that had light surface rust from sitting. With rust deposits its better to get them off than to let the ring run through it.

[Chemmie]

I'd skip the sand paper and use a fine green scouring pad just on the top centre of the photo where there is the visible orange rust. 60* strokes to half-*ssed match the honing. Totally diffr'nt rice bowl than a Quincy QR25.

[Spike00513]

problem is you may have an ovaled or elongated cylinder bore. if you do, you might burn oil.

as far as touching your cylinder bores, you should never unless you plan to rebuild the motor. generally speaking if the visual damage cannot catch a fingernail, or can be felt you should be OK.

Is this because you then have to measure, and choose piston size in accordance to match it?
Also, I heard pistons can be different. Like some model pistons might expand differently with temperature, and create a knocking sound when cold, upon cold start-up, when they are still shrunk and rattling around inside of the bore, before expanding tighter with heat. Or so I heard once.

Also saw once posted in B5 S4 subforum, someone using something like this, with a cordless drill, on their block.
Not sure what it is, or how such things compare to factory-level machine shops.
For example, Cosworth is the name of a company that specializes in internal combustion engines (ICE). They probably know more about the topic than my noob self.

So far, my stock engine doesn't seem to really burn oil. Which I'm glad about.
I don't have to keep track of/worry about/or remember to add oil every now and then, or carry around a spare liter jug, since it seems to stay the same level.
Or, if I were to run out of whatever oil is in it to match it, the potential of using gas station random cheap dino oil. Not sure if that contaminates it.
I heard one brand name for those oils, was even caught bottling old used recycled oil. You know the stuff you dump at Autozone after an oil change? That, put into a bottle. And sold right back to you for $1-3/ea (per quart or liter)

[Biged243]

Your talking about forged pistons. And that is a type of honer. Doing it with that you have to be careful so that you can make the proper cross marking to give the proper oiling. It can be done with it but you have to be careful.

[Kevin C]

I'd skip the sand paper and use a fine green scouring pad just on the top centre of the photo where there is the visible orange rust. 60* strokes to half-*ssed match the honing. Totally diffr'nt rice bowl than a Quincy QR25.

I have used fine grade paper as well 3M abrasive pads for light cleanup of bores. Adding an angle as you clean works. The only downside to using the abrasive pads is they shed abrasive. I actually was doing this last night on an old air compressor I'm getting back into service as a spare. It got the surface rust off and added a light cross hatch. The idea is to not remove the plateau surface, just clean up the deposits.

[Chemmie]

Is this because you then have to measure, and choose piston size in accordance to match it?
Also, I heard pistons can be different.

An ovalled bore cannot be measured with the intention of placing a larger piston in it without processing first. Typical wear may be 0.004-0.0045" on the diameter and you wouldn't buy pistons that are simply larger in this case. If the bores are too far gone, the block is bored larger in 0.030" increments and the appropriate overbore piston/ring set purchased. You can buy 0.030"/0.060" over sized piston/ring sets, for example.

The hone shown is a bottle-brush/ball hone. Follows the cylinder closely and is good for inexperienced noobs as it's not aggressive. Still, one can easily ruin a bore by being overzealous with any type of hone. I prefer 3-stone flex hones as it's easier to see the individual stone movement and time your stroke accordingly. The rigid stones will cut thier own path; far easier than a bottle brush hone to ruin a bore. Some ATF on either type of hone works well for cutting oil- let's it bite rather than slide.

Pistons haven't been circular since the 1930's. RE: modern pistons, following the heating cycle in CAD shows the thermal growth in areas of higher mass, and some pretty remarkable designs have been devised to have the piston closely approximate a circle at operating temperature while oblong cold.

[BARRY]

you should never use sandpaper...at the MOST you can use a scotch brite pad as it doesn't leave deposits in the metal(yes the one you use to clean your pots and pans). always try to follow the cross hatch pattern, but remember you're always taking a chance when you touch the cylinder bore. only touch the high spots that catch a finger nail. i've seen people freshly hone a bore and attempt to reuse piston rings...that thing burned oil like no tomorrow. you effectively are creating an unmated surface.

[Seerlah]

Rag with a chemical of choice. Just seams like stain removal a kitchen grease cleaner with rag can get (ie Fantastic). I would have personally used Simple Green with a rag. Spray the rag, not cylinder bore.

[joe biker]

I wouldn't use a scotch brite pad,I would wipe it down with WD 40.
It's not only a cleaner but also a lube.
I have used it in engines with stuck piston rings with great success.
GM doesn't advise scotch brite as mechanics were using the disc to clean gaskets off motors only to
find particles clogging oil ports causing engine failure.
Wouldn't hone unless your replacing the rings.


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[Spike00513]

I wouldn't use a scotch brite pad,I would wipe it down with WD 40.
It's not only a cleaner but also a lube.
I have used it in engines with stuck piston rings with great success.
GM doesn't advise scotch brite as mechanics were using the disc to clean gaskets off motors only to
find particles clogging oil ports causing engine failure.
Wouldn't hone unless your replacing the rings.

I've never built engines so I wouldn't know. But in terms of other places, I've heard people say that WD-40 is a fake lube, and that it's really just a solvent that displaces/washes away lube, and then attracts dirt.
Unless it also gets used as a penetrating oil? Because you mention using it on stuck piston rings. Not sure if anything else is better for that. I know AeroKroil exists, but not much about it.

I just know for stuff like key lock cylinders, and door hinges, people say to use stuff other than WD-40.

Maybe that is not relevant here.

[Chemmie]

I wouldn't use a scotch brite pad,I would wipe it down with WD 40.
It's not only a cleaner but also a lube.
I have used it in engines with stuck piston rings with great success.
GM doesn't advise scotch brite as mechanics were using the disc to clean gaskets off motors only to
find particles clogging oil ports causing engine failure.
Wouldn't hone unless your replacing the rings.

WD-40 is NOT a lubricant. When left to dry, after the solvent evaporates, it leaves a sticky, gunky mess. Hence why not to use it on lock cylinders as Spike said. Much better to use a real penetrating oil like Fluid Film or Kroil.

GM can advise whatever they want, the situtation has nothing to do with the OP's situation. No one here recommended using an air grinder w/pads- in any case, he has no oil galleries to worry about hitting. And he's not removing pistons so obviously won't hone in any event.