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Glazed bores?

ROBDEN

By ROBDEN
in Boat Building & Maintenance

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Tony Brooks Veteran II

Tony BrooksDonate to Canal World

Posted
Posted

If the glazed bores prevent the rings making a good seal to the cylinder then you will get similar symptoms to worn rings. In no particular order any or all of:-

 

Poor cold starting with lot of white "smoke" from the exhaust.

Burning oil.

Bluish exhaust smoke.

Excess/more crankcase pressure that might cause engine oil leaks.

 

If the rings are sealing then there will be no detrimental effects.

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ROBDEN Rising Star

ROBDEN

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Other than popping the head off I don't know and as for detrimental effect I have no idea but would love to be enlightened.

Phil

 

Hi Phil.

You and me both.

It's often mentioned on here but as far as I'm aware no one has explained exactly what the symptoms are.

Rob....

If the glazed bores prevent the rings making a good seal to the cylinder then you will get similar symptoms to worn rings. In no particular order any or all of:-

 

Poor cold starting with lot of white "smoke" from the exhaust.

Burning oil.

Bluish exhaust smoke.

Excess/more crankcase pressure that might cause engine oil leaks.

 

If the rings are sealing then there will be no detrimental effects.

 

Thanks Tony.

You posted that while I was tryping.

 

So, what will cause the bores to glaze?

 

Rob....

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nicknorman Veteran II

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Posted (edited)

From Cox's Engineering website:

 

"Cylinder bore glazing results from prolonged light load running, particularly during the running-in process, and leads to the formation of a surface coating or skin derived from chemicals present in the oil and fuel. If glazed cylinder bores are examined, it is not unusual to see the honed crosshatch markings beneath a super-smooth, highly polished, varnish-like layer. Bore glazing occurs at low speed and light load operations, particularly resulting from blow-by in new engines. Exhaust gases passing piston rings in newly built or re-built bores can react with oil and wear products, forming a golden-coloured varnish glaze. Most engine manufacturers warn against the potential problem. Sabb and Lister-Petter are in surprising agreement on the subject, as shown in their operator's handbooks. In each case the wording is identical: Long periods of light or no-load running early in the engine's life may lead to cylinder bore glazing and high lub oil consumption. Cummins, Perkins and MAN all have issued directives limiting the run time at idle to prevent bore glazing. "

Edited by nicknorman
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Bee Veteran

Bee

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I seem to remember a manufacturer, Lister? doing a bit of research into chrome plated liners and rings, not a success, the things seized, probably due to no oil film on the liners, also there was research into PTFE coatings on rings, dunno what happened to that but it seemed to be dropped after a while. In the end it seems that old fashioned cast iron works best for liners maybe with chrome plated rings.

Vim? can you still get it? you could always try a handful of sand. No , Don't. Really.

Edited by Bee
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Timleech Veteran II

Timleech

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I seem to remember a manufacturer, Lister? doing a bit of research into chrome plated liners and rings, not a success, the things seized, probably due to no oil film on the liners, also there was research into PTFE coatings on rings, dunno what happened to that but it seemed to be dropped after a while. In the end it seems that old fashioned cast iron works best for liners maybe with chrome plated rings.

 

It's a long standing bit of knowledge that chromed rings should never be used in chromed bores. Chromed bores used to be common, but seem to have dropped out of favour - maybe just not worth the extra cost?

 

Tim

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MoominPapa Veteran II

MoominPapa

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I seem to remember a manufacturer, Lister? doing a bit of research into chrome plated liners and rings, not a success, the things seized, probably due to no oil film on the liners, also there was research into PTFE coatings on rings, dunno what happened to that but it seemed to be dropped after a while. In the end it seems that old fashioned cast iron works best for liners maybe with chrome plated rings.

Vim? can you still get it? you could always try a handful of sand. No , Don't. Really.

Lister use/used chrome plated bores extensively, under the trade name "Listard". The plating process included a final step where the current was reversed to give a slightly porous surface that retained oil.

 

MP.

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steamraiser2 Proficient

steamraiser2

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Posted

 

It's a long standing bit of knowledge that chromed rings should never be used in chromed bores. Chromed bores used to be common, but seem to have dropped out of favour - maybe just not worth the extra cost?

 

Tim

 

Improvements in engine oil technology has reduced the need for liner chroming. The Listard process was brought in to extend the life of liners, particularly in generator use, the Lister JPs being the classic example.We see a lot of old JPs with the original liners still in place after seventy years so it works well. Seen quite a few aftermarket plain liners completely worn out after five years or so too. A clear indicator of why it is so important to use OEM standard parts and the right oil.

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Timleech Veteran II

Timleech

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Improvements in engine oil technology has reduced the need for liner chroming. The Listard process was brought in to extend the life of liners, particularly in generator use, the Lister JPs being the classic example.We see a lot of old JPs with the original liners still in place after seventy years so it works well. Seen quite a few aftermarket plain liners completely worn out after five years or so too. A clear indicator of why it is so important to use OEM standard parts and the right oil.

 

I seem to remember that the 'Listard' labels referred to Van der Horst patents.

Van der Horsts were a company (in East Anglia, IIRC) who specialised in liner chroming, and did reclaiming work on big liners for ships' engines etc. They seem to have folded some time in the last 15 years.

 

Tim

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gazza Veteran

gazza

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While we are talking about bore plating, chrome plating was common on two stroke motorcycles, then Kawasaki used the Nikasil process on the two stroke KR1/KR1S along with the KX motocrossers and the KLX series of fourstoke engines. It meant you could do away with the steel liner and run the piston directly in the cylinder casting.

 

Some found them difficult to live with suffering unexpected seizing. It was also difficult to find someone who could salvage a worn or damaged cylinder - that has changed nowadays though!

 

In the motor industry Ford developed the old CVH engine with Yamaha, it got stretched to 1.7 litres for the Puma, this was achieved by doing away with the liner and going down the Nikasil route, Jag used it in the late 90's v8 engine too.

There were problems with bore wear and oil consumption - particularly if the wrong oil was used.

 

Its something that seems to come and go with engine designers at a whim - done right can be very effective.

 

We had a 1.7 puma, the engine was an absolute gem - cracking car.

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Tony Brooks Veteran II

Tony BrooksDonate to Canal World

Posted
Posted (edited)

To try to answer some of the questions raised.

 

Adding to what Nick posted. It seems the engine design also has some effect on its propensity to glaze the bore, particularly the exact shape of the top part of the piston. (pistons are actually oval and tapered slightly). I think it may depend upon the depth of taper. If the temperature in the vicinity of the cylinder wall face is not sufficient to burn the oil film away to dust it may "cook" the oil into a varnish. Listers sent me a report years ago that also implicated the oil's additive pack (see the Barrus oil topic). This is why I feel it unwise to use oil API grades higher than necessary.

 

Since Morris dropped Ambesta I know of no protect to remove the glaze. If Vim is introduced into the air cleaner the result will be vertical scores, not the off horizontal diamond shaped hatching that is required. If I suspected my bores had glazed I would go onto a tideway and really thrash the engine for several hours but it probably would not work. Otherwise the least I would do is to take the head off, set each piston in turn to bottom dead centre and hone or glazebust each bore. A glazebuster typically looks like a shaft for an electric drill fitted with 3 rubber flaps. Emery cloth is wrapped around the flaps. It is put into an oiled bore and spun while being moved up and down. It may still be necessary to take the pistons out to get at the full bore.

 

As glazing is to do with oil film, temperature and blow by a yet to be run in engine where the rings have yet to bed to the bores is more likely to glaze under cool cylinder temperature conditions than one that is well run in but any engine could glaze given the right (wrong) conditions. Hence my advice to seek opportunities to really thrash it from time to time in the hope you burn some the the varnish off.

Edited by Tony Brooks
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dmr Veteran II

dmr

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Posted

I believe one very well known engine maker "officially" sanctioned their technicians to use the handful of Vim cure, but on strict instructions not to do it whilst the customer was present!

As Tony says its not ideal as it is likely to produce mostly vertical "honing" though turbulence may reduce this.

I believe the Morris's product was discontinued as it used chemicals that were bad for the environment. I think it was also an abrasive so again not an ideal approach.

I guess if the engine is a lost cause then its worth trying Vim to extend the life before a rebuild.

 

..........Dave

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Taslim Rising Star

TaslimDonate to Canal World

Posted
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To try to answer some of the questions raised.

 

Adding to what Nick posted. It seems the engine design also has some effect on its propensity to glaze the bore, particularly the exact shape of the top part of the piston. (pistons are actually oval and tapered slightly). I think it may depend upon the depth of taper. If the temperature in the vicinity of the cylinder wall face is not sufficient to burn the oil film away to dust it may "cook" the oil into a varnish. Listers sent me a report years ago that also implicated the oil's additive pack (see the Barrus oil topic). This is why I feel it unwise to use oil API grades higher than necessary.

 

Since Morris dropped Ambesta I know of no protect to remove the glaze. If Vim is introduced into the air cleaner the result will be vertical scores, not the off horizontal diamond shaped hatching that is required. If I suspected my bores had glazed I would go onto a tideway and really thrash the engine for several hours but it probably would not work. Otherwise the least I would do is to take the head off, set each piston in turn to bottom dead centre and hone or glazebust each bore. A glazebuster typically looks like a shaft for an electric drill fitted with 3 rubber flaps. Emery cloth is wrapped around the flaps. It is put into an oiled bore and spun while being moved up and down. It may still be necessary to take the pistons out to get at the full bore.

 

As glazing is to do with oil film, temperature and blow by a yet to be run in engine where the rings have yet to bed to the bores is more likely to glaze under cool cylinder temperature conditions than one that is well run in but any engine could glaze given the right (wrong) conditions. Hence my advice to seek opportunities to really thrash it from time to time in the hope you burn some the the varnish off.

I go with what the man said.

 

Some times the 'Italian tune up' works. I did farm stuff for a while and if you got a white smoking, oil eating tractor, especialy small Fords, we would put the biggest plough it will take on its' back and hammer some pasture giving the engine beans so a thrash on a tideway may serve.

 

If that didn't work, and it often did, it's head off pistons out and measure what you got. Sometimes all that is needed is clean up the pistons and run the glaze buster down the bores. Again often small Fords, Those used as yard tractors that were left to tick over were the usual suspects.

 

If you have a laptop a £10 enoscope of Fleabay lets one see if it's just glazed or if you need to dig deeper in the purse.

 

They're also usefull for checking bilges and finding out if 'it' dropped behind the fridge.

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