This thesis has a wealth of information in it.
http://www.diva-portal.org/diva/getDocument?urn_nbn_no_ntnu_diva-209-1__fulltext.pdf
http://www.diva-portal.org/diva/getDocument?urn_nbn_no_ntnu_diva-209-1__fulltext.pdf
Deposit formation on cylinder liner surfaces
- Thread starter JAG
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I agree. Great find JAG!
Seems the papers is on engines used in large ships, no?
The focus is on marine engines but pages 15-16 discuss non-marine engines.
I just hope the oil and feul mfgs additize to prevent the problem, after the first few pages I kinda lost interest so I skimmed and hit my head on the wall a couple times to keep in focus. Is that the N.G. engine part? Pg 15and 16
It says:
Quote:
Deposits on cylinder liners have been reported in many applications
including tractor diesel engines, four stroke gasoline engines found in
motorcycles, vintage cars, light propeller aircraft and lawnmowers. The
distinction between lacquer and glaze appears to be used primarily for
medium speed engines. In case of other engines the term 'glaze' or 'bore
glaze' appears universally applied to liner deposits with appearances
ranging from invisible to dark black and blueish deposits.
Bore glaze is frequently reported during break in following cylinder
overhaul. Montgommery [16] found that a smoothing surface coating
consisting of Fe3O4 and a carbon was formed during simulated runningin
experiments. These constituents were also found in authentic glaze
formed during run-in. A mechanic with extensive engine service and
teaching experience provided the observations on the topic of glaze
formation presented in Table 2-1. [17]
Personal correspondence with this author has established that glaze in
these engines is typically black or blue in colour and is related to the use
of multigrade oils. The use of a high performance monograde reportedly
eliminated this problem. It was also established that the engines
frequently were running on less than full oil levels.
Quote:
TABLE 2-1 ABOUT BORE GLAZE IN SMALL ENGINES [17]
- Glaze describes oil burned and baked onto a surface.
- Glaze is insulative, very hard, polishes to a high shine, wears
piston rings, and can be removed only with an abrasive material or a cylinder hone.
- A glazed bore is invariably the result of surplus lubricating oil being left behind by the piston rings because they have not been "pushed hard enough" against the cylinder bore surface to remove most of the oil.
- The piston rings of any engine under a too light load will not be pressed as firmly against the cylinder bore surface as in an engine under a heavier loading.
- Piston rings scrape harder against the cylinder bore surface
during the combustion and exhaust strokes as the gas pressure
increases between the piston rings and piston ring grooves.
- When excess oil is left behind it is burned onto the bore surface and forms a very hard glazed smooth finish.
- Light or under load running will always result in a glazed bore
- The time taken to glaze a bore will vary according to the
lubricating oil used, the load applied, the length of time run under light load, and local air temperature.
- Any engine with a glazed cylinder bore will always use lots of oil and will cause complete engine failure if not quickly andorrectly repaired.
- A glazed bore will usually be restored to standard by re-honing and fitting new rings.
- A glazed bore is not an engine fault it is an operator or application problem.
- Sometimes the only solution to overcome light loading is to include a dummy load such as an electric bar heater on a generator.
- Most petrol engines prefer 60% to 80% loading if running for long periods of time.
- Diesel engines are "happier" with 75% to 90% loading if running
for long periods of time.
- Engines (using correct grade and quantity of frequently changed
oil) that run at variable speeds and changing loads very rarely get a glazed bore.
Quote:
Deposits on cylinder liners have been reported in many applications
including tractor diesel engines, four stroke gasoline engines found in
motorcycles, vintage cars, light propeller aircraft and lawnmowers. The
distinction between lacquer and glaze appears to be used primarily for
medium speed engines. In case of other engines the term 'glaze' or 'bore
glaze' appears universally applied to liner deposits with appearances
ranging from invisible to dark black and blueish deposits.
Bore glaze is frequently reported during break in following cylinder
overhaul. Montgommery [16] found that a smoothing surface coating
consisting of Fe3O4 and a carbon was formed during simulated runningin
experiments. These constituents were also found in authentic glaze
formed during run-in. A mechanic with extensive engine service and
teaching experience provided the observations on the topic of glaze
formation presented in Table 2-1. [17]
Personal correspondence with this author has established that glaze in
these engines is typically black or blue in colour and is related to the use
of multigrade oils. The use of a high performance monograde reportedly
eliminated this problem. It was also established that the engines
frequently were running on less than full oil levels.
Quote:
TABLE 2-1 ABOUT BORE GLAZE IN SMALL ENGINES [17]
- Glaze describes oil burned and baked onto a surface.
- Glaze is insulative, very hard, polishes to a high shine, wears
piston rings, and can be removed only with an abrasive material or a cylinder hone.
- A glazed bore is invariably the result of surplus lubricating oil being left behind by the piston rings because they have not been "pushed hard enough" against the cylinder bore surface to remove most of the oil.
- The piston rings of any engine under a too light load will not be pressed as firmly against the cylinder bore surface as in an engine under a heavier loading.
- Piston rings scrape harder against the cylinder bore surface
during the combustion and exhaust strokes as the gas pressure
increases between the piston rings and piston ring grooves.
- When excess oil is left behind it is burned onto the bore surface and forms a very hard glazed smooth finish.
- Light or under load running will always result in a glazed bore
- The time taken to glaze a bore will vary according to the
lubricating oil used, the load applied, the length of time run under light load, and local air temperature.
- Any engine with a glazed cylinder bore will always use lots of oil and will cause complete engine failure if not quickly andorrectly repaired.
- A glazed bore will usually be restored to standard by re-honing and fitting new rings.
- A glazed bore is not an engine fault it is an operator or application problem.
- Sometimes the only solution to overcome light loading is to include a dummy load such as an electric bar heater on a generator.
- Most petrol engines prefer 60% to 80% loading if running for long periods of time.
- Diesel engines are "happier" with 75% to 90% loading if running
for long periods of time.
- Engines (using correct grade and quantity of frequently changed
oil) that run at variable speeds and changing loads very rarely get a glazed bore.
Thanks .that should be a stickie because that would answer break in ,Italian tune ups and extending engine life,Why single grade oils are recommended for fixed rpm engine operation. This is important info.
Agreed!
This article explains why my tired old 100 hp tractor slurped oil when I first got it, then gradually slowed and almost stopped after I started using it in heavy load situations. It shows both how the deposits accumulate and how they de-accumulate with a change in engine in operation. A lot this article wooshed high over my inadequately educated head but there was enough for a low-brow like me to follow along. Great find JAG! I need to check this section of the board more often!!!
FYI, my tractor fits this paper to a Tee. It had spent the previous 10 years or so doing easy stuff, like mowing and wagon hauling. Because it's a low compression, DI diesel (15:1 CR), it's cold blooded. It essentially won't warm up at idle and slobbers like mad. By using it for heavy tillage only, eliminating needless idling and light work (I have a small utility tractor for that) oil consumption was drastically reduced from 4-6 quarts a season (only as much as 70 hours per season) to about a quart a season now, if that. Pretty dramatic.
I had always thought the oil consumption was mostly due to fuel dilution. An oil change with a heavier oil (15W40 replaced straight 30) slowed it down, but even after that oil change, it took a full season of hard work to see a big drop in consumption and a coupla seasons to see the current result. The article explains the six ways deposits can be removed by a change in operational modes.
FYI, my tractor fits this paper to a Tee. It had spent the previous 10 years or so doing easy stuff, like mowing and wagon hauling. Because it's a low compression, DI diesel (15:1 CR), it's cold blooded. It essentially won't warm up at idle and slobbers like mad. By using it for heavy tillage only, eliminating needless idling and light work (I have a small utility tractor for that) oil consumption was drastically reduced from 4-6 quarts a season (only as much as 70 hours per season) to about a quart a season now, if that. Pretty dramatic.
I had always thought the oil consumption was mostly due to fuel dilution. An oil change with a heavier oil (15W40 replaced straight 30) slowed it down, but even after that oil change, it took a full season of hard work to see a big drop in consumption and a coupla seasons to see the current result. The article explains the six ways deposits can be removed by a change in operational modes.
Last edited:
It's good to hear such a positive experience that ties in with this paper, Jim. Thanks.
"Most petrol engines prefer 60-80% loading"?
"Diesel engines 75-90%"?
Not a chance.
I've seen the guts of as many engines as most anybody. Nobody runs their street mom/n/pop vehicles like that.
I don't think I've ever seen that type of glazing.
Decades ago, engine bores would sometimes wear pretty smooth, but I haven't seen it for a long time, and never the deposit type of glazing.
"Diesel engines 75-90%"?
Not a chance.
I've seen the guts of as many engines as most anybody. Nobody runs their street mom/n/pop vehicles like that.
I don't think I've ever seen that type of glazing.
Decades ago, engine bores would sometimes wear pretty smooth, but I haven't seen it for a long time, and never the deposit type of glazing.
Originally Posted By: mechtech2
"Most petrol engines prefer 60-80% loading"?
"Diesel engines 75-90%"?
Not a chance.
I've seen the guts of as many engines as most anybody. Nobody runs their street mom/n/pop vehicles like that.
I don't think I've ever seen that type of glazing.
Decades ago, engine bores would sometimes wear pretty smooth, but I haven't seen it for a long time, and never the deposit type of glazing.
This qualifier was at the end of the two sentences you quoted: "if running for long periods of time." I think that means running for long time periods between start-up and shutdown.
Yes, if you take off the qualifier like you did from the quote, it becomes a suspect statement. But that shouldn't be done with any statement.
"Most petrol engines prefer 60-80% loading"?
"Diesel engines 75-90%"?
Not a chance.
I've seen the guts of as many engines as most anybody. Nobody runs their street mom/n/pop vehicles like that.
I don't think I've ever seen that type of glazing.
Decades ago, engine bores would sometimes wear pretty smooth, but I haven't seen it for a long time, and never the deposit type of glazing.
This qualifier was at the end of the two sentences you quoted: "if running for long periods of time." I think that means running for long time periods between start-up and shutdown.
Yes, if you take off the qualifier like you did from the quote, it becomes a suspect statement. But that shouldn't be done with any statement.
Jim the ultimate Italian tune up!!!
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