Glaze busting - what's the wisdom?

[davidbfox]

I've grasped the nettle. I'm rebuilding my old Yanmar YSM 12 because it pressurises the crankcase and uses as much oil as diesel.

I am renewing piston rings and big end shells and have renovated cylinder head and injector and cleaned out exhaust elbow etc. Because this is a horizontal single cylinder engine it is possible to do all this without removing the engine.

I was not planning to replace the cylinder liner (mainly because the engine is still in the boat and I have no puller - perhaps not the best reason).

My caretaker (who used to be a car mechanic) sucks his lip and says this is a false economy and I should replace liner or at very least glaze bust the old one.

I've never done that before and hesitate to wreck the liner through injudicious surgery.

So, advice please ... Glaze bust? If so how?

Thanks in advance.

 

[Quandary]

Its known as honing and any good auto workshop can do it. Basically you are scoring the metal slightly so that it hold oil on the surface. Recommended for any rebuild. Not something you can do yourself though.

 

[sailorman]

I've grasped the nettle. I'm rebuilding my old Yanmar YSM 12 because it pressurises the crankcase and uses as much oil as diesel.

I am renewing piston rings and big end shells and have renovated cylinder head and injector and cleaned out exhaust elbow etc. Beacuse this is a horizontal single cylinder engine it is possible to do all this without removing the engine.

I was not planning to replace the cylinder liner (mainly because the engine is still in the boat and I have no puller - perhaps not the best reason).

My caretaker (who used to be a car mechanic) sucks his lip and says this is a false economy and I shoud replace liner or at very least glaze bust the old one.

I've never done that before and hesitate to wreck the liner through injudicious surgery.

So, advice please ... Glaze bust? If so how?

Thanks in advance.

glaze bust = a bore honing devise it has emry cloth affixed to it devise attached to a drill to spin it & rugh-up the bore.
do yourself a favour & fit a new liner & "O" ring.
as its a horizontal engine the bore wears @ the bottom & any moisture settles in the bottom as well.
when i rebuilt my YSE 12 Co32 i replaced the liner.
i have in stock a riser i had made for exhaust ( L & R/h thread ) its yours for p&p. i had 2 made used 1

 

[earlybird]

I am renewing piston rings
I was not planning to replace the cylinder liner

I did much the same years ago with a YSE8, but included main bearings. The new rings greatly reduced oil consumption. I was probably too poor to include a new liner and piston. I certainly didn't glaze-bust the liner in any serious way, but I might have given it a hand scrub with some fine abrasive paper.
BTW, The liner bore was worn only a very small amount, but I have a faint memory that the replacement top ring was stepped, in order to cater for any slight ridge at the top of the bore, which otherwise might break it. Perhaps someone with a more recent memory of this might comment.

 

[Heckler]

I've grasped the nettle. I'm rebuilding my old Yanmar YSM 12 because it pressurises the crankcase and uses as much oil as diesel.

I am renewing piston rings and big end shells and have renovated cylinder head and injector and cleaned out exhaust elbow etc. Because this is a horizontal single cylinder engine it is possible to do all this without removing the engine.

I was not planning to replace the cylinder liner (mainly because the engine is still in the boat and I have no puller - perhaps not the best reason).

My caretaker (who used to be a car mechanic) sucks his lip and says this is a false economy and I should replace liner or at very least glaze bust the old one.

I've never done that before and hesitate to wreck the liner through injudicious surgery.

So, advice please ... Glaze bust? If so how?

Thanks in advance.

Ive got a glaze buster, its like a 3 legged puller with carborundum strips on the legs, spring loaded, it fits in a std eleccy hand drill chuck, a few runs up and down the bore does the job. OR you can get a flap wheel that will just fit in the bore and run it up a down a few times, you wont do any damage if you are slow and careful.
Stu

 

[Ubergeekian]

Its known as honing and any good auto workshop can do it. Basically you are scoring the metal slightly so that it hold oil on the surface. Recommended for any rebuild. Not something you can do yourself though.

I beg to differ. It's a piece of cake to do yourself, as long as you have access, an electric drill and a cylinder hone - which costs twenty quid or so and looks like this

If the rings are being replaced then a glaze bust is a very good idea indeed.

 

[andy01842]

As other have said glaze busting is a very good idea. A slow drill and the hone lubricated with paraffin is the way to go. A 30deg cross hatch is the desired pattern. The hone needs to exit both ends of the cylinder but only about one third the length of the stones. The most important bit is to wash out all traces of the grit. Ridge dodgers rings are also needed (stepped ring) to prevent the top ring breaking.

 

[Heckler]

I beg to differ. It's a piece of cake to do yourself, as long as you have access, an electric drill and a cylinder hone - which costs twenty quid or so and looks like this

If the rings are being replaced then a glaze bust is a very good idea indeed.

Thats the one ive got, if anyone is near and wants to borrow it you all know where it is
Stu

 

[cimo]

A 30deg cross hatch is the desired pattern. The hone needs to exit both ends of the cylinder but only about one third the length of the stones. The most important bit is to wash out all traces of the grit. Ridge dodgers rings are also needed (stepped ring) to prevent the top ring breaking.

interesting - well its something new i've learned today. how do you get the cross hatch? is this patterned on the stone? are there different stone types? where do the ridge dogers go?
thanks rgds
c

 

[Ubergeekian]

interesting - well its something new i've learned today. how do you get the cross hatch? is this patterned on the stone? are there different stone types? where do the ridge dogers go?

You get the 30 degrees by moving the hone up and down the cylinder bore at half the speed with which it's moving along the walls. The ridge dodgers are, as andy01842 said, piston rings. The existing rings will have worn away the bore a bit where they touch, leaving a small step in the bore at the ends of travel. New rings will kiss these on every stroke, so it's sensible to fit a top ring with a small cutout at the top edge so it can't make contact with the lip. For some reason this isn't generally done for the bottom ring, and if it wasn't late I might be able to work out why.

 

[andy01842]

The cross hatch is achieved by moving the hone up a down the bore as is rotates, that why you need a slow drill, 200/400rpm. The stones come in different grades. A medium grit is best about 300 to 400.
The ridge dodgers is the top ring with the step to the top so that it dose not hit the wear ridge at the top of the bore. Hope this helps
Andy

 

[cimo]

cheers chaps
learning all the time!
rgds
c

 

[oldharry]

(Sucking lip also) Yes but... if the bore is badly worn, glaze busting is not going to help much as the new rings wont seat properly. They will want to take a near perfect circle, and a worn bore may be quite oval.

Using one of the new rings, insert the ring into the bore, and check the end gap; that is the gap where the ring is split. This must be within the specified limits for the engine. Do this at 3 - 4 points down the bore. At the same time, use the feeler gauge to see whether the ring is touching the bore all round. Anywhere its not touching the bore is wear and will cause compression problems. And all your hard work will be wasted.

If that all measures up, then you can start glaze busting, but you do have to ensure the scoring is around 30 degrees as suggested, or you will go on having problems with oil and compression loss.

Otherwise bite the bullet and fit a new liner. At least then you will know the bore is good!

 

[Bilgediver]

Its known as honing and any good auto workshop can do it. Basically you are scoring the metal slightly so that it hold oil on the surface. Recommended for any rebuild. Not something you can do yourself though.

Yes you can and I have done many boat engines for neighbours including one of these horizontal Yanmars working on the pontoons.

All you need is a speed controlled cordless drill and a triple stone hone with spring loaded stones. Mine came from The USA but no doubt available here.

It takes about 3 minutes to generate the required herringbone effect to the required depth to promote oil seal and give a fresh bedding in surface.

 

[Quandary]

Sorry, I know it is not complicated but does require skill and knowledge. I have watched it being done but never done it and was impressed by how little effort it took the mechanic to get the right pattern. If I was the OP who has never done it or seen it done, I would not attempt it.
Would you let the OP with his current experience hone your bores? I would still recommend he gets someone who knows how to do it to check the wear and then show him first.That would be better than rebuilding his engine to little benefit.
We have all levels of skill and knowledge on here, sometimes it does less harm to recommend caution.

 

[boatmike]

Thats the one ive got, if anyone is near and wants to borrow it you all know where it is
Stu

Thanks Stu. I was beginning to despair. As usual a lot of bad advice on here. Don't use emery or flap wheels. This is the correct tool and nothing else!
One point not mentioned here is that if there is a significant lip left at the top of the bore it will break the top ring very quickly if a new one is fitted. The solution to this is to ensure you fit a STEPPED first compression ring not a standard one and make sure the step is uppermost. A far far better solution would be to get it professionally rebored and fit oversized piston and rings.

 

[macd]

One point not mentioned here is that if there is a significant lip left at the top of the bore it will break the top ring very quickly if a new one is fitted. The solution to this is to ensure you fit a STEPPED first compression ring

Correct. It's not mentioned in some of the posts. As for the rest...

 

[Ubergeekian]

A far far better solution would be to get it professionally rebored and fit oversized piston and rings.

It's got a liner. Just replace the liner.

 

[Monique]

+1^

You cannot remove all the filings after honing unless you have a good shop performing the work.

As your engine is a horizontal 1 lunger, I'd remove the old liner and fit a new one.

Use old liner as a paper weight.

 

[boatmike]

It's got a liner. Just replace the liner.

Rather depends on the price of a new one don't you think? Replace if cheap and available (which at the age of this it might not be) Otherwise remove and have it bored out. Should be reasonably cheap to do and no reason why not.