Glaze busting - what's the wisdom?

[gordmac]

If you have a significant lip at the top of the bore (feel with your fingernail) I would suggest it is too worn and change the liner although you may be ok with a hone and a stepped ring. Ideally you should measure the bore in several places, at 90deg in maybe 3 heights. You used to be able to get a tool to remove the step (Eastwood tool company?). The hone pictured is the tool for the job but (herisey I know!) I used to do it by hand with emery paper.
Make sure you clean all the grit out though.
You will need to gap the rings correctly, too tight and they break, too loose and you lose a (small)bit of power and burn a little bit oil. Similarly if you don't de-glaze you might use oil and drop power. I used to use a particular procedure to bed the rings in (car), not so easy with a boat maybe but it does need to work a bit rather than tick over.

 

[Ubergeekian]

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.

Since this engine is linered, it is quite possible that oversize pistons simply aren't made. I've owned four cars for which they are not: on my DS and Reliant you are expected to replace the standard line/piston sets and on the VW Camper Van and 2CV you replace the pistons and cylinders.

Of course the liners/cylinders cost a bit, but you save the cost of the rebore and since only standard parts are made the costs can be significantly lower than oversizes.

 

[davidbfox]

Thanks as always. What did people do before forums?

Only standard rings are available.

I think I will need to replace the liner too. I hadn't thought about breaking the rings.

Only standard liner is available. They appear to cost well over £100.

This is turning into an expensive job. Rings, gaskets, £110; injector rebuild £45; valves etc £65. No guarantee of success.

(Though maybe not so much - it's recently cost £350 to replace my bike exhaust and £350 for a car service.)

How do you get parts from abroad? I have never managed it.

David

 

[sailorman]

Thanks as always. What did people do before forums?

Only standard rings are available.

I think I will need to replace the liner too. I hadn't thought about breaking the rings.

Only standard liner is available. They appear to cost well over £100.

This is turning into an expensive job. Rings, gaskets, £110; injector rebuild £45; valves etc £65. No guarantee of success.

(Though maybe not so much - it's recently cost £350 to replace my bike exhaust and £350 for a car service.)

How do you get parts from abroad? I have never managed it.

David

google "French Marine Motors" Brightlingsea uk stockists normally have stuff ex stock
from memory there is an "O" ring @ the base of the liner dont forget to order it

 

[Norman_E]

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.

I was told that the hone should not be used dry, but with plentiful thin oil, and every trace of the oil and the grit it will contain washed out afterwards.

You should measure the bore for wear. If the engine is well used cylinder wear needs to be checked. In any engine the cylinder tends to wear most at the top of the area of ring travel, becoming both slightly bucket shaped, and slightly oval. You need to find out if the wear in an old engine is within limits for simply honing the bore and fitting new rings, or whether a rebore and oversize piston (or a new cylinder liner if rebore is not permissible), are required.

 

[sailorman]

I was told that the hone should not be used dry, but with plentiful thin oil, and every trace of the oil and the grit it will contain washed out afterwards.

You should measure the bore for wear. If the engine is well used cylinder wear needs to be checked. In any engine the cylinder tends to wear most at the top of the area of ring travel, becoming both slightly bucket shaped, and slightly oval. You need to find out if the wear in an old engine is within limits for simply honing the bore and fitting new rings, or whether a rebore and oversize piston (or a new cylinder liner if rebore is not permissible), are required.

this engine is prone to wear on the bottom of the liner as it a horizontal cylinder + any moisture present lays in the same place all the time

 

[Heckler]

Thanks as always. What did people do before forums?

Only standard rings are available.

I think I will need to replace the liner too. I hadn't thought about breaking the rings.

Only standard liner is available. They appear to cost well over £100.

This is turning into an expensive job. Rings, gaskets, £110; injector rebuild £45; valves etc £65. No guarantee of success.

(Though maybe not so much - it's recently cost £350 to replace my bike exhaust and £350 for a car service.)

How do you get parts from abroad? I have never managed it.

David

I think everyone has concentrated on the honing bit and the ridges. BEFORE you start lashing out, MEASURE the thing, feel if there is a ridge with your finger nail, if there isnt wear why change it? I will also say that I have rebuilt hundred of engines in my professional life. In my early life (ie skint!) I used to just replace rings, even in badly worn engines, in those all I ever did was clean the ring lands out with a broken piston ring, emery the bore, paying particular attention to the ridge to ease the transition and away we would go. I have NEVER used, let alone seen stepped rings (I am not saying they dont exist) and I never had a prob with broken rings with a rebuilt engine as detailed above.
So if I was in your position I would measure it first to see if it warrants a new liner, then make a decision on whether to replace or hone.
Stu

 

[Ubergeekian]

Thanks as always. What did people do before forums?

Only standard rings are available.

I think I will need to replace the liner too. I hadn't thought about breaking the rings.

Only standard liner is available. They appear to cost well over £100.

This is turning into an expensive job. Rings, gaskets, £110; injector rebuild £45; valves etc £65. No guarantee of success.

skipper_stu gives excellent advice below. To it I will only add that if (check carefully!) there is enough wear to justify replacing the liner, then make sure you replace the piston as well. Sure, it's extra expense but you have then zero-houred the whole top end of the engine.

 

[Allan]

I was taught, many years ago how to hone the bores of race car engines. I never felt confident doing it with a hand drill. I modified a drill stand, piller type, that could be clamped in place as central as possible. The honing tool I used had three springs, one on each leg. The guy who worked on Patch, at the time the most successful formula ford 1600 engine, used to hone by hand with emerycloth.
Allan

 

[AntonW]

Bore wear

Measure yes but has to be measure to make sure its within tolerance and not oval over it full length.
Probably worn cos its an old engine thats been used and burning oil, which normally means it is oval and worn. Horizontal bores need to seal better than vertical bores or you get into oil consumtion (I think its somthing called gravity). I have seen people re-ring old worn out engines spend a fortune on gaskets seals etc and then say it fixed. The engines still consumed oil and smoked just as bad if not worse. Do it once properly and it will cost you the least in the long run. Also three legged honing tools do not look good sticking out of your head, if you are not careful and the tool exits the bore while rotating you can be seriously injured. You wont need to hone the new bore, but use low quality oil for the first 20 to 50 hours to bed the rings in, then go to a high quality oil to give long life. Take your time do it properly once and you will have spent the minimum time and money. Why is people always have the time to do the job properly the second time but not the first?

Anton

 

[Avocet]

Hmmm. This "lip" thing. Presumably if the honing tool rides up on to the lip, you've had it, because as soon as that happens, the stones will only be touching on the lip and at the bottom (part way down the cylinder)? At best that will stuff your "heringbone" battern and at worst, might it score an annular ring part way down the bore?

Also, although I know stepped rings exist, I've never been quite sure why one might need them on a low revving marine diesel. Presumably, the lip was created by the top ring reaching TDC - so why should the piston travel any higher once the engine has been rebuilt? Is it the case that the liner can sit lower down when re-asembled?

All I'd say to the OP is to have a think about what you want the engine to do. I'm not familiar with it but I gave Avocet's engine a "freshen up" a few years ago as it was proving hard to start. It's a raw water cooled engine for which fewer and fewer parts are now available, so it's days are numbered. I just changed big and small end bearings, honed the bore and lapped the valves in, but spent very little money (copper head gaskets so I just had to anneal them and re-use). If you're just trying to get another few years out of it, I'm not sure being inexperienced need be a problem - in fact it's probably better to learn on an engine that's going to be scrapped soon!

 

[Heckler]

Hmmm. This "lip" thing. Presumably if the honing tool rides up on to the lip, you've had it, because as soon as that happens, the stones will only be touching on the lip and at the bottom (part way down the cylinder)? At best that will stuff your "heringbone" battern and at worst, might it score an annular ring part way down the bore?

Also, although I know stepped rings exist, I've never been quite sure why one might need them on a low revving marine diesel. Presumably, the lip was created by the top ring reaching TDC - so why should the piston travel any higher once the engine has been rebuilt? Is it the case that the liner can sit lower down when re-asembled?

All I'd say to the OP is to have a think about what you want the engine to do. I'm not familiar with it but I gave Avocet's engine a "freshen up" a few years ago as it was proving hard to start. It's a raw water cooled engine for which fewer and fewer parts are now available, so it's days are numbered. I just changed big and small end bearings, honed the bore and lapped the valves in, but spent very little money (copper head gaskets so I just had to anneal them and re-use). If you're just trying to get another few years out of it, I'm not sure being inexperienced need be a problem - in fact it's probably better to learn on an engine that's going to be scrapped soon!

Your thoughts tie in with mine, the stepped ring thing is I suspect a bit like in a computer mag advice column, "When using regedit, make a back up first" everyone says it but no one ever does it!
I had an engine in the workshop in Angola, (one of the boys had got a VW passat from somewhere) it had big grooves down a couple of the bores, no chance of getting spares. They had stripped it and brought it for Mister Stu to work his magic. I cleaned the bores with petrol and emery, teased the rings out of the pistons and cleaned the lands up. I then got some Baker Lok, a two part compound used for glueing well pipe together, filled the groves and let it go off. I then emery ied the cylinders to roughly round, got a Chevvy brake cylinder hone and honed it out. We put it all together using the old gaskets and gasket cement. It started and ran OK, a little smokey but OK. It was still running when I left there!
Stu

 

[Allan]

Hmmm. This "lip" thing. Presumably if the honing tool rides up on to the lip, you've had it, because as soon as that happens, the stones will only be touching on the lip and at the bottom (part way down the cylinder)? At best that will stuff your "heringbone" battern and at worst, might it score an annular ring part way down the bore?

Also, although I know stepped rings exist, I've never been quite sure why one might need them on a low revving marine diesel. Presumably, the lip was created by the top ring reaching TDC - so why should the piston travel any higher once the engine has been rebuilt? Is it the case that the liner can sit lower down when re-asembled?

The stepped rings are to compensate for wear in the originals. As the bores wear so do the top ring edges. The idea is that when new rings are fitted the non worn top edges could come into contact with the ridges and break. It seems logical to me but I have not seen any proof either way.
Allan

 

[vyv_cox]

Your thoughts tie in with mine, the stepped ring thing is I suspect a bit like in a computer mag advice column, "When using regedit, make a back up first" everyone says it but no one ever does it!
Stu

In the past when I have bought replacement rings to go into used bores they always came with a stepped top ring. I always bought and had machining done by Senar's in Birkenhead and their first question was always as to whether the bore was worn. It was necessary to ensure the top rings were the right way up when fitting them. I haven't reringed a car engine for many years, so this may or may not be the case now.

 

[earlybird]

An unstepped rng may well work, I don't know, but since a stepped ring should be just as easy to buy, and is certain to be OK, then why take the chance?
Some people are anxious to spend the OP's money and complicate this job by removing the engine, buying new piston and liner etc etc. And that still leaves a worn crankshaft, cyl. head, gears etc.
As mentioned in my earlier post, my YSE was vastly improved re. oil consumption just by fitting a new set of rings and "glaze busting" by hand with a piece of emery-cloth. This is an easy job with the engine in-situ, and all that is risked is the price of the rings and possibly a gasket.
I suggest to the OP that if the wear lip at the top of the bore is less than ~.1 to .15 mm, then just replace the rings. You might be pleasantly surprised

 

[reeac]

Stepped rings

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.

The bottom of the liner is a very well lubricated environment unlike the top so that's why no step develops there.

 

[andy01842]

The reason that there is more wear at the top of the bore than at the bottom is because when the piston is at the bottom of it stroke ether the inlet or the exhaust valve is always open i.e. there is little pressure in the cylinder. When the piston is at the top of the compression/power stroke there is max pressure in the cylinder and there fore max load on the piston rings.
The top of the cylinder is also hotter than the well lubricated bottom. Oil dose a lot of the cooling.

 

[J*O*A*M*O*N]

greetings..HUhhh stepped rings you say..can't say I ever even heard of them. They sound like a good idea, I've rebuilt many of the notoriously finicky VW water cooled flat fours and never had any problems with the rings breaking. I always deglazed the liners by hand with emery paper, wipe the bore out with an oily rag to start with then a paper towel and WD till the towel comes out white and your good to go. One tip re: the O-ring on the bottom of the liner is to use some white lith. grease in the bore to help the seal untill the engine goes thru a few heating and cooling cycles and it really seats well, also keeps it from twisting when you slide the liner into the block, a common problem with the VW's don't know about these engines, they sound very similar though. I ended up doing so many because my friend ownes a VW shop and I had a much better track record with my rebuilds than he did. lol thanks all for all the great stuff I learn here thought it was about time I started giving back. Ed

 

[Heckler]

In the past when I have bought replacement rings to go into used bores they always came with a stepped top ring. I always bought and had machining done by Senar's in Birkenhead and their first question was always as to whether the bore was worn. It was necessary to ensure the top rings were the right way up when fitting them. I haven't reringed a car engine for many years, so this may or may not be the case now.

Vyv
whenever I have fitted new rings I always have looked for the mark on the top ring which indicates which way it goes and never thought anything about it, but they certainly werent stepped as such.
Stu

 

[Avocet]

I think they are marked "top" even if they're not stepped because they have a slight taper to the edge, but I'm not sure.

I've certianly seen stepped rings and I agree that if they are available and similarly priced to flat ones, there sems little point in taking the risk.

I have seen broken top rings (once) on a racing engine that was over-revved. I was told (but am not sure if it's true!) that when you have a slight lip in the bore AND you rev the engine hard, the rods can stretch a little and allow the top of the ring to hit the lip. Not sure that would ever be a problem on a diesel boat engine though!