Glazed bores

[RockyF75]

What is it?

Re: the idling vs switching off engines thread.

Heard it quite a few times and haven't really worked out or been told exactly what it is, anyone care to explain?

[chimpboy]

It is literally a varnish-like coat that forms inside the cylinder from chemicals in the fuel and oil. There are meant to be tiny "grooves" in the cylinder to hold lubricating oil; if instead there's a polished finish because of glazed bores you lose lubrication and all hell breaks loose.

That's my understanding anyway, and it could be completely arse about.

[dogbreath_48]

It is literally a varnish-like coat that forms inside the cylinder from chemicals in the fuel and oil. There are meant to be tiny "grooves" in the cylinder to hold lubricating oil; if instead there's a polished finish because of glazed bores you lose lubrication and all hell breaks loose.

That's my understanding anyway, and it could be completely arse about.

I'm not sure if the main issue is about losing lubrication, but more about losing compression - maybe both.

Occurs when an engine is operating at low RMP and/or low load for extended periods - such is my understanding anyway.

My old diesel landcruiser feels lazy after plodding around town for a few weeks - a good run on the highway (i.e. a good thrashing ) improves the flexibility and outright power output of the engine.

-Stu

[alien]

also known as an italian tune up =) (rev the shite out of the engine for a few minutes to clear out built up crud).

generally, the way it was explained to me, to avoid glazing, try to operate the engine at different rev ranges as often as possible... ie" dont sit on 60km/hr all week doing 2000rpm in 5th... drop to 4th now and then etc.

[mikesmith]

glazing is not like an instant thing to happen. does not like just happen cause u have been sitting in traffic for ages. i think u will find it is a lot easier for it to happen to a new engine in its run in period rather than an older engine.

glazing happens more when a car is at idle ie no real load on the motor just turning over. if it was because u were say sitting at a certain speed all the time eg 2000rpm in 5th on freeway nearly engine would be fucked once u take it on a long drive would it not??

ppl talk about it like it happens a lot but if a engine has been built properly and run in properly u do no see many dramas with them.

[Jacked]

also happens from turning the car off strait after you rev it. If your a p-plate tool that does this with his loud commodore etc.

[chimpboy]

also happens from turning the car off strait after you rev it. If your a p-plate tool that does this with his loud commodore etc.

How come?

[RockyF75]

glazing is not like an instant thing to happen. does not like just happen cause u have been sitting in traffic for ages. i think u will find it is a lot easier for it to happen to a new engine in its run in period rather than an older engine.

glazing happens more when a car is at idle ie no real load on the motor just turning over. if it was because u were say sitting at a certain speed all the time eg 2000rpm in 5th on freeway nearly engine would be . once u take it on a long drive would it not??

ppl talk about it like it happens a lot but if a engine has been built properly and run in properly u do no see many dramas with them.

Guess that's why my mates bike had to be run in at different rev ranges, I told him to just sit it there idling for the 15hrs or how ever long it was, but the instructions said no

[coxy321]

Hhmmm. You're opening a can of worms there re engine break in procedures......

[Jacked]

also happens from turning the car off strait after you rev it. If your a p-plate tool that does this with his loud commodore etc.

How come?

Was taught as an apprentice that glazing is caused by unburnt fuel on the cylinder walls over time building up and varnishing. When doing that there is alot of unburnt fuel left in the chamber especially with carby cars.
with EFI its not as bad but still quite a bit off excess unburnt fuel.

Theres no way to prove it but it makes sence to me. Especially with carby cars.

[RockyF75]

Hhmmm. You're opening a can of worms there re engine break in procedures......

Dare I ask.... why?

[coxy321]

Hhmmm. You're opening a can of worms there re engine break in procedures......

Dare I ask.... why?

No. You daren't.

[chunks]

Its also know as bore polishing, its from excessive idling and cold running due to insufficient oil being splashed/squirted up onto the cylinder walls, resulting in inadequate lubrication of the rings. The result is lower compression, harder starting and higher oil consumption.

[Clint]

This site has a good expanation for engine run in and glazing

http://www.engineproblem.com.au/main.htm
Under 'Procedures' from the menu on the left there is a section on run in procedures. Not a bad read

"There is a fine line between the pressure exerted on the ring to obtain enough contact to bed-in and to actually overheating and scuffing the ring face. Light loads on initial run-in will allow combustion to pass by the rings. This escaping combustion burns & oxidises the oil & bore fragments forming a chemical coating on the honed bore. This chemical coating is known as "Glazing" and has the appearance of golden varnish with the original hone finish being very visible. Once an engine is glazed up it is usually impossible to achieve complete bed-in of rings. The glazed coating prevents the ring to bore contact required to match up or bed-in rings"

[CWBYUP]

Hhmmm. You're opening a can of worms there re engine break in procedures......

Dare I ask.... why?

I have always been taught to run in a jet ski engine......







WOT for at least 2 hours.

[-Scott-]

also happens from turning the car off strait after you rev it. If your a p-plate tool that does this with his loud commodore etc.

How come?

Was taught as an apprentice that glazing is caused by unburnt fuel on the cylinder walls over time building up and varnishing. When doing that there is alot of unburnt fuel left in the chamber especially with carby cars.
with EFI its not as bad but still quite a bit off excess unburnt fuel.

Theres no way to prove it but it makes sence to me. Especially with carby cars.

As I understand it (explained by my grandfather, an old-school mechanic), it's primarily an issue with carb-fed engines, but for a slightlly different reason.

During normal running, there's a very thin coating of oil on the cylinder walls (and rings?) which provides corrosion protection.

Give that final "rev" before switch off, and excess fuel ends up in the cylinder, which condenses, runs down the walls and washes the protective oil away from the ring/cylinder contact point. Within hours, minute amounts of corrosion occurs.

Over time, these minute amounts of corrosion add up to accelerated wear of both rings and bore.

There's no reason to do "the rev" and good reason not to do it.

[-Scott-]

Hhmmm. You're opening a can of worms there re engine break in procedures......

Dare I ask.... why?

I have always been taught to run in a jet ski engine......

WOT for at least 2 hours.

There's site (somewhere on the web) by a bloke with some radical thoughts on engine porting (for motorbikes). All his detailed explanations make perfect sense to me, and his (claimed) results are impressive - he claims his race motors out-perform the factory bikes, but I've never tried to verify his claims through independent sources.

His recommended run-in procedure is to idle until everything is warm, then do a series of full-throttle power (under load) runs to bed in the rings.

His argument was (is?) that the rings need to be "bedded in" with significant combustion pressure, which helps to force the rings against the cylinder walls. Running in "lightly" doesn't produce as good a ring to bore seal. He backed his claims with "dyno results" showing that peak power would increase (by only a few hp per run) on each full-throttle run, which was, to him, evidence that the rings were bedding in on each run, providing better compression (and power) on subsequent runs.

I have NFI how "valid" (scientifically "robust") his tests are, but I can't fault his theories.

If I ever re-build an engine (which is on the cards) I'll be trying his theories.

Scott

[V8Patrol]

His recommended run-in procedure is to idle until everything is warm, then do a series of full-throttle power (under load) runs to bed in the rings.

X2

only way I ever 'ran in' my race bike engines

&

the only way I've ever ran in a car engine too

[coxy321]

Hhmmm. You're opening a can of worms there re engine break in procedures......

Dare I ask.... why?

I have always been taught to run in a jet ski engine......

WOT for at least 2 hours.

There's site (somewhere on the web) by a bloke with some radical thoughts on engine porting (for motorbikes). All his detailed explanations make perfect sense to me, and his (claimed) results are impressive - he claims his race motors out-perform the factory bikes, but I've never tried to verify his claims through independent sources.

His recommended run-in procedure is to idle until everything is warm, then do a series of full-throttle power (under load) runs to bed in the rings.

His argument was (is?) that the rings need to be "bedded in" with significant combustion pressure, which helps to force the rings against the cylinder walls. Running in "lightly" doesn't produce as good a ring to bore seal. He backed his claims with "dyno results" showing that peak power would increase (by only a few hp per run) on each full-throttle run, which was, to him, evidence that the rings were bedding in on each run, providing better compression (and power) on subsequent runs.

I have NFI how "valid" (scientifically "robust") his tests are, but I can't fault his theories.

If I ever re-build an engine (which is on the cards) I'll be trying his theories.

Scott

Righto. Since this has apparently taken off, here's the guy you are talking about Scott:

http://www.mototuneusa.com/break_in_secrets.htm

I used this break in procedure for my DRZ70. It is the first (and probably the only) new bike i have owned, so i thought i'd break it in right.

I did days of researching re: break in procedures, and found Moto Man's procedures made the most sense, so i used them. But in my other searching, i found numerous other workshops/racers/builders/manufacturers/developers shooting down his procedures and offering a completely different procedure. Some with explanations, some without, some with proof on paper, some without.

Needless to say, my bike has had no issues, uses no oil etc - so i'm happy. The only problem i have is Suzuki Service continually giving me the wrong valve clearances.

We also did a similar break in for my better halfs new car, although Mazda suggest that you "drive the car as per normal".

[80's_delirious]

if you want it to go hard, run it in hard

[Ashchaya]

Righto. Since this has apparently taken off, here's the guy you are talking about Scott:

http://www.mototuneusa.com/break_in_secrets.htm" onclick="window.open(this.href);return false;

I used this break in procedure for my DRZ70. It is the first (and probably the only) new bike i have owned, so i thought i'd break it in right.

I did days of researching re: break in procedures, and found Moto Man's procedures made the most sense, so i used them. But in my other searching, i found numerous other workshops/racers/builders/manufacturers/developers shooting down his procedures and offering a completely different procedure. Some with explanations, some without, some with proof on paper, some without.

Needless to say, my bike has had no issues, uses no oil etc - so i'm happy. The only problem i have is Suzuki Service continually giving me the wrong valve clearances.

We also did a similar break in for my better halfs new car, although Mazda suggest that you "drive the car as per normal".

5 or so years ago I got a fully rebuilt/reco'd 3L motor in my Hilux. I was planning on doing exactly what this mototune guy says. When I went to pick her up I found they had already done 82km of gentle driving around town. I asked them if they did any breaking in procedures and they said you don't need to, "just drive it normal now". According to the info on that guy's site, this meant I had missed my chance at bedding in the rings properly.

I drove away with a vehicle that blew more black smoke than it ever had before ("that's just how they are mate"), AND it used 1 litre of oil every 5,000km. This, from a brand new engine. It also spun a bearing after 20,000 kays, although that's probably unrelated to run-in procedures.

On Monday, I will be picking up another Hilux with a completely rebuilt/reco'd 3L motor from a different place. As long as these guys don't rob me of my chance to bed the rings in, I'll hopefully have some pretty good data to support or disprove mototune's ideas. In around 5,000km (which I will do in three weeks).

[rockcrawler31]

On a similar note, detroit two stroke diesels like to be driven like a rental. Most truck owners i've ever spoken to say that unless you rev the living daylights out of it every change, and make it work like a hooker on $2 tuesday they start dribbling oil everywhere.

I was going to put a DD4-53T in my chev truck until i found this out. With the rod run cruises i had in mind i was told it would suffer.

I'm waiting for someone to bring up the old Ajax trick/furphy/arguement.

My 1HZ gets redline gearchanges more often than it doesn't and as a result it seems to like to rev more freely than some other 1hz's i've driven.

Curious

[Guy]

I got an old Mazda paddock thrasher many moons ago ... when I first got it .. it was a nightmare to get started or get to idle ... would need to rev huge and sidestep the clutch to get it to take off without stalling ... after a few days of running it off the tacho round the paddocks it loosened up heaps ... would start withing a couple of seconds of the key being turned and idled so smooth you could barely tell it was running ... ( until the exhaust fell off .. )

Italian tune up sorted it out ...

[XTREME MMM]

I'm waiting for someone to bring up the old Ajax trick/furphy/arguement.


Curious

I was only thinking that my self. I have seen that used many years ago during my apprenticeship, guess what it worked.

When I have built motors, I just tell the customer to drive normally, don't load up the motor for too long and vary the speed. Also don't loose any sleep if you happen to do a few more revs then normal.

Treat it like you treat a new car, or even better a rental.

Cheers
David

[simkell]

Glazed bores occur due to combustion temperatures not being high enough to burn all the fuel and oil in the combustion chamber. This generally occurs more with two stroke diesel's when left to idle for too long. Most detroit diesel have a high idle built into the governor to prevent this, by increasing the idle to 1200rpm. Older petrol engine had similar problems but nowhere near the problems diesel's would. Engines like being being used in there optimum torque and horsepower ranges, (to low = glazing, to high = premature wear).

Breaking or bedding in engines, warm the engine up to operating temperature. Drive the vehicle under all conditions for say 50km. Flush engine oil and drive as normal. Most wear occurs during initial start up, cams hate it.

[slosh]

Glazed bores occur due to combustion temperatures not being high enough to burn all the fuel and oil in the combustion chamber. This generally occurs more with two stroke diesel's when left to idle for too long. Most detroit diesel have a high idle built into the governor to prevent this, by increasing the idle to 1200rpm. Older petrol engine had similar problems but nowhere near the problems diesel's would. Engines like being being used in there optimum torque and horsepower ranges, (to low = glazing, to high = premature wear).

Breaking or bedding in engines, warm the engine up to operating temperature. Drive the vehicle under all conditions for say 50km. Flush engine oil and drive as normal. Most wear occurs during initial start up, cams hate it.

I was told when rebuilding a Ford V8, that the first run of the new engine must get up to 2000rpm (could have been higher, I forget) as soon as possible and hold it there for 20 mins or so, then drain oil. Under no circumstances was the engine to be left to idle. The reason for this is to get oil to the cam quickly. The cam being made of mild steel, when starved of oil (as idleing will do) will fill the new motor with steel shavings and thus very short engine life.

[simkell]

Slosh you are right, too many beers last night whilst typing, we some engines the oil pump is driven off the dissy shaft so you can bring oil pressure up with a drill. Once started bring up to 2000/ 2500 rpm no load to bed in cam like you said for around 10 minutes. By then the engine is well and trully warm, drive vehicle as said above or drain oil and go for the drive. The bigger the lift more wear occurs. I have also seen hydraulic lifters not bled properly and when doing valve clearances, the clearances where done up to tight and eventually destroyed the cam.

[Ashchaya]

5 or so years ago I got a fully rebuilt/reco'd 3L motor in my Hilux. I was planning on doing exactly what this mototune guy says. When I went to pick her up I found they had already done 82km of gentle driving around town. I asked them if they did any breaking in procedures and they said you don't need to, "just drive it normal now". According to the info on that guy's site, this meant I had missed my chance at bedding in the rings properly.

I drove away with a vehicle that blew more black smoke than it ever had before ("that's just how they are mate"), AND it used 1 litre of oil every 5,000km. This, from a brand new engine. It also spun a bearing after 20,000 kays, although that's probably unrelated to run-in procedures.

On Monday, I will be picking up another Hilux with a completely rebuilt/reco'd 3L motor from a different place. As long as these guys don't rob me of my chance to bed the rings in, I'll hopefully have some pretty good data to support or disprove mototune's ideas. In around 5,000km (which I will do in three weeks).

I have returned!

Lucky me, all they'd done after putting the rebuilt motor back in was park it in their underground garage. So yep, I ran it in just as mototune describes. I even did a couple more rev ups and engine brakings to be sure.

I then did a roadside oil and filter change, right there on the spot. (Delo 400 and Fleetguard LF3487 synthetic media)

Then I drove it to work (Sydney to Canberra) varying the revs between 1900 and 3500, again, just to be sure. I couldn't even see any smoke in my mirrors for the whole trip.

Did another oil and filter change at 1000km. Now at 5000km, still not a drop of top up oil required. At slow speeds I can now see some smoke, but burning diesel without a turbo is always going to produce at least some black smoke.

Better than blowing black smoke like a plane crash and losing 1 litre of oil every 5000km, which is what the softly-softly method gave me.

I'm convinced.

[Struth]

It is like a very tough varnish on the bore caused by a chemical reaction between fuel and oil. It fills in the microcpic valleys in the bore and makes the bore smooth. this prevents the rings from bedding in correctly and allows compression to bypas the compression rings.

[old lux]

when i built my motor was told short shift gears around town and drive it hard. pumped 15 pounds of boost into it for a good 5-7000ks and she drives like a dream. have now dropped the boost back down to 9 pound and runs like a new car. doesnt go threw oil no issues. (turbo 3L hilux)

also heard from many people with the new v8 vruiser bout burning oil but every1 i talked to was driving in nicely. talked to other people who treat it like a race car and drove it like they stole it that they dont go threw a drop of oil.

new quad i bought 750 bruteforce. asked about run in proceedures they said thewre is none and said when he dirst turned the key to his ZX9 was at the race track. so for the last 15 hours my brute has been treated like i race bike