Is heat cycling beneficial or detrimental when breaking in engine?

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705
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Indiana
Yes I know it really doesn't matter, but when breaking in a new engine is heat cycling engine important? Is it just better to break it in with as few thermal cycles as possible, varying rpm, varying load, ect. The engine in question is actually a 3cyl yanmar diesel in a tractor, and these engines use a little oil until broken in. I believe these actually have a noticeable breaking period vs a new automotive engine. I was always under the impression that heat cycling when breaking in was beneficial. Thoughts?
 
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1,991
Location
Minnesota
If I had a dime for every discussion on break in...lol. I don't think it matters, nor do I think the majority of answers you will get will be based upon anything of value to you. Look at it this way, over use and time, your pistons are going to travel up and down inside their bores, the crankshaft will rotate in their bearings. Machining rigides will be smoothed out etc. And that's whether or not you do this process in a "certain way". Just plain use of the engine is going to break it in. Will some methods be faster? Sure, but does it really matter? Take any advice you get with a grain of salt because the majority of it will be just un-scientific, un-proven BS anyway.
 
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1,967
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USA
Originally Posted by 5AcresAndAFool
Yes I know it really doesn't matter, but when breaking in a new engine is heat cycling engine important? Is it just better to break it in with as few thermal cycles as possible, varying rpm, varying load, ect. I was always under the impression that heat cycling when breaking in was beneficial. Thoughts?
In general terms it is and is not and this comes from the full spectrum of designing machines through commissioning then eventually a reman. First a "break in" has to be defined. Most people define it is where various surface finishes, tolerances and components "wear to mate" and settle in in terms of displacement, alignment and so forth. ( and any combination of the above) Theres the school that says you need to break in everything- they are 100% correct Theres the school that says if its "built right" theres no need for an "official" break in- they are also 100% correct The truth lies in-between and rests on 2 specific things The quality of that rebuild ( for the purpose of this answer lets agree to assume the quality is correct because otherwise its an infinite set of "what ifs") The other thing is the physical properties of the machine ( what we call the service factor in industry) such as shaft deflections, thermal growth, internal stress distribution of the housings and a host of other things machine specific. These create unique wearing scenarios and stresses unique to that specific machine that cant be effectively modeled or anticipated. So even with the "perfect rebuild" and 10 qts. of uncle bobs unicorn oil there is that 3rd element that has a significant contribution to "settling in" ( total scope of the effect is machine specific) and machine wear. So, yes they are important in the general- how much and how many cycles is usually either experience or T&E.
 
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1,991
Location
Minnesota
"Theres the school that says you need to break in everything- they are 100% correct" But doesn't use of an engine do this anyway? I mean at 10,000 ,miles I think my engine is "broken in" whether I intentionally did it or not....
 
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1,328
Location
south dakota
I always just take it easy on a new engine except it's difficult to do on things like a snowblower or power washer. My new 9.8 boat motor required it to be broken in at a low throttle and not run wide open. I think taking it easy is best.
 
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1,967
Location
USA
Originally Posted by philipp10
But doesn't use of an engine do this anyway? I mean at 10,000 ,miles I think my engine is "broken in" whether I intentionally did it or not....
Yes it does but at the "nanometer" level there is a razor thin line ( virtually invisible and with very fluid boundaries) between "break in wear" where all things new wear into each other and normalize transforms into "normal wear" where all things wear uniformly according to the load and other factors. Where that line is and how defined the boundaries usually rests somewhere between the quality of the rebuild, the actual loads of the machine and the ramp up period to full load.
 
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2,506
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Deep in the heart of Jersey
Well being it's an expensive motor to replace, I would follow the mfgrs suggestion on how to break it in. It will probably run better and last longer if you do what they say. Can't see why they would give you bum info on that.,,
 

CT8

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15,397
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Idaho
The farms around here have $500,000.00 tractors and combines they put then to work right away.
 

5AcresAndAFool

Thread starter
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705
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Indiana
Originally Posted by CT8
What does the owners manual recommend?
Surprisingly nothing. First oil change interval on these used to be at 50 hours, now its 200. The manual cautions against low speed or idle operation generally degrading the oil faster. My friend has the identical unit and he had run his mostly at idle with no known ill effects. I have been using mine in short intervals, bringing everything up to full operating temp, including engine oil, each time. I have been varying load and engine speed not lugging it.
 

5AcresAndAFool

Thread starter
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705
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Indiana
I will also say that there is John Deere "Break in oil" in the crankcase, which I believe is 10w30. I will probably have a oil analysis done around 25 hours or so and go from there. People who have changed the oil early in these units recommend using break in oil for the first 200 hours.
 
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7,905
Location
MI
I looked at my workplace 25HP JD 4115 manual (Yanmar engine) and it also has no break in procedures other than change the oil and filter at 50 hours and avoid excessive idleing. It sounds like you are doing things right. After it is warmed up, use it! Don't baby it too much. Don't shut it down while very hot (I do this for the life of the tractor - let it cool down at moderate rpm a few minutes after hard work) My larger (75HP) John Deeres DO have sections on engine break in, but nothing too specific other than "avoid excessive idling". Other sections say the engine and tractor are ready for use directly from the factory. Check fasteners, etc. more often at first. [Linked Image]
 
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1,340
Location
texas
disassemble the engine and pull the pitpstons, take off the rings and get s small ring file to remove the sharp edge from the rings top and bottom edge. moly coat tye bores and reinstall the pistons, but some hot gas in it and run it like you stole it.
 
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26,358
Location
PNW
Originally Posted by philipp10
But doesn't use of an engine do this anyway? I mean at 10,000 miles I think my engine is "broken in" whether I intentionally did it or not....
Pretty much every vehicle manufacturer says the engine is broken in with 1,000 to 1,500 miles on it (ie, OK to go WOT and rev to redline). Sure, there will be a little more "break in" after that, but "break-in" after the initial break-in is just another name for additional wear.
 
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