Crack in the piston?

Is this a crack in the piston?
Or is it jas a bump in the casting?
It is from a Case 1370.
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a184402.jpg

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Henrik Jansson,I looks like it is cracked from the photos.Looks like the crack runs down into the crater.It could be checked with a dye penetration test kit.
 
does looked cracked . You can also soak it in gas for hour or two an than blow it dry with air an observe if gas bleads out of crack.Found ours on 1070 that way.
 
Is it just my imagination or are there two other cracks right near the corner of each valve relief? The picture seems to show erosion out from each end of the center at the crack, the rest of the piston shows a sharp margin at the top of the bowl but the picture seems to show a rounded down area at that point or is that just an illusion?
 
I saw that too.

A whole engine kit really seems like the way to go, even if the the freight is expensive.
 
If it is cracks, it might be 4.
Yes, it also something that looks like a small pit near the middle, but maybe that is something from the casting?
The biggest crack, if it is a crack, looks more like the painted picture up in the left. It is like it first goes up and then down. Like a volcano.
The injectors has been bad and were replaced a few years ago.
I can not see any cracks on the other pistons.
But my thought was that it might could be irregularities in the surface made from the casting?

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Looks like cracks to me. As you said it had bad injectors previously, looks like they might have done that, the cracks corrospond with the two opposite spray holes in the injector.

What kind of history does this engine/tractor have? How many hours since new pistons? Light work/chore tractor or heavy tillage/chopping?

The last major engine overhaul I did was an early Cat 3406B that had about million orginal miles on the top end, every single piston was cracked on the crown, truck ran cross county, lots of hard miles running produce from California to New York, there's a couple of big hills it had to go over a few times too.
 
The tractor is from 1976, and it has 5300 hours, but I do not know if that is correct.
I do not believe any piston has been replaced before, I only know that sleeve number 4 has been replaced and 3 of the rod bearings has been replaced by the former owner.
Since I bought I only pull a 9 meters harrow with it. The engine then runs on 1500 rpm. I do not think it is very heavy, but it is not easy work either. Somewhere in between?
I use it for about 100 hours/year now.
 
You don't lug it down to 1500 do you? Under load, I don't like to have them drop 150 rpm below high idle when working in the field. Much more than that, I feel, is hard on the engine.
 
In what way is that hard on the engine?
Low rpm gives better fuel economy.
By the way, can someone explain why the part number that is marked on the top of the piston A 76165 does not is the same as in the parts catalog that says: A 146697 ?
 

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