What glazes a cylinder bore?

[cmsapms]

I found this link which claims there's no such thing as a glazed cylinder and that, so long as the cylinder dimensions are OK, there's more harm than good in honing to "break the glaze" before installing new rings. (there's mention of some SAE research that explains why)

So, what is "glaze"? Does it exist? Why is a glaze much more likely to develop if the engine idles excessively during the running-in period than once the rings/bores are run-in?

On a related point, I've just had a block over-bored and "plateau" honed and am fitting new pistons/rings. This is the first time I've seen a "plateau" finish. To me it looks and feels already run-in. I'm used to honed surfaces that tear the crap out of paper towel when cleaning them. This plateau hone has resulted in a smooth surface. In fact it has the appearance of the sort of bore that I would have automatically had re-honed prior to re-ringing

So, what's the PH engineers' thoughts on modern honing, glazed bores and what, if any, break-in procedure is correct for new rings on a plateau hone? What is being achieved in running in rings against a bore surface that is round/parallel and has had the honing "peaks" removed?

Thanks

[Workshop]

When I installed rings on Mitsu motors , they directed not to hone the cylinder. This was on re-rings where the rings had gone soft. Bores were fine, rings were toast.

[GavinPearson]

cmsapms said:

I found this link which claims there's no such thing as a glazed cylinder and that, so long as the cylinder dimensions are OK, there's more harm than good in honing to "break the glaze" before installing new rings. (there's mention of some SAE research that explains why)

So, what is "glaze"? Does it exist? Why is a glaze much more likely to develop if the engine idles excessively during the running-in period than once the rings/bores are run-in?

On a related point, I've just had a block over-bored and "plateau" honed and am fitting new pistons/rings. This is the first time I've seen a "plateau" finish. To me it looks and feels already run-in. I'm used to honed surfaces that tear the crap out of paper towel when cleaning them. This plateau hone has resulted in a smooth surface. In fact it has the appearance of the sort of bore that I would have automatically had re-honed prior to re-ringing

So, what's the PH engineers' thoughts on modern honing, glazed bores and what, if any, break-in procedure is correct for new rings on a plateau hone? What is being achieved in running in rings against a bore surface that is round/parallel and has had the honing "peaks" removed?

Thanks

Glaze is where you have worn the crosshatch hone marks from the bore. The danger is that if you put a new ring in a bore that is not being fed adeqate lubricant, then it may fail / scuff / score the bores.

The best thing to do is follow the piston manufacturer's recommendations for hone specification - Rvk, Rk, Cv, angle etc, it is not a one spec works for all situation. One possible issue that may be experienced with a plateau hone is torn and folded metal. This won't bee good for the rings. It also helps to have the bores honed on a proper machine designed to do that job and no other.

In terms of running in, avoid high engine speeds and high loads, and change the oil at say 50% of the recommended interval.