I Still Hate My Tractor II

[moship]

Well she blew up again, not sure what happened but I'll find out tomorrow. I think it had like 4 hours on the new pistons.

I was expecting to see a rod through the block or a window in the pan, but didn't see anything in the photo.

Good luck and curious to see the damage and understand the root cause.

 

[The Fred]

Looks like #4 piston expanded too much and seized in the bore. One of the others has started to stick the oil ring.

These are aftermarket pistons from a reputable supplier, I spent much time measuring and comparing them to OEM and the cost was far far less but the price wasn't worth it.

These all still measure identical to the OE piston except for the one that seized, it is .002" smaller after scuffing off the coating, notice also the clean piston (OEM Kubota with 500 hrs.) still has the coating. The aftermarket pistons did have the anti-scuff coating on them but it's long gone in no time.

I tear down plenty of engines for a living and I've not seen the coating come off of the piston skirt ever.

When I find time I'll clean a couple of these and throw them in the oven then measure again. My guess is the aluminum alloy expands more than OEM alloy does. Although I haven't checked the hour meter I think I put about 5 hours on it, mostly running them in at low load. It's only when I blew snow this week wide open that it started knocking and quit then upon restart it ran on 3 cylinders.

First photo is Kubota piston with 500 hours with the worn ring land. Second is two aftermarket pistons although dirty and hard to tell. Third is the one that seized.

 

[moship]

Fred,

Thanks for supplying the pictures.

When the engine was rebuilt, did you rebore or just run a hone to clean it up a bit? If overbored, how much? What amount piston clearance were you running?

Any chance you have a restricted oil passage restricting oil to this cylinder?

 

[The Fred]

Pistons were stock size, cleaned up the bores with a hone. This time it gets bored .5mm. I'd like to find pistons with a steel top land; I'd throw that turbo back on and run the crap out this again. Obviously ring lands are the weak point with boost.

The bad news is I threw the 75 inch snow blower on the CK2610 and I get to be outdoors again like when I was a kid. The CK2610 handles the blower not too bad with turf tires and no chains, actually much better than expected of course it's a light gear tractor so much of the torque goes to the PTO.

 

[fried1765]

Looks like #4 piston expanded too much and seized in the bore. One of the others has started to stick the oil ring.

These are aftermarket pistons from a reputable supplier, I spent much time measuring and comparing them to OEM and the cost was far far less but the price wasn't worth it.

These all still measure identical to the OE piston except for the one that seized, it is .002" smaller after scuffing off the coating, notice also the clean piston (OEM Kubota with 500 hrs.) still has the coating. The aftermarket pistons did have the anti-scuff coating on them but it's long gone in no time.

I tear down plenty of engines for a living and I've not seen the coating come off of the piston skirt ever.

When I find time I'll clean a couple of these and throw them in the oven then measure again. My guess is the aluminum alloy expands more than OEM alloy does. Although I haven't checked the hour meter I think I put about 5 hours on it, mostly running them in at low load. It's only when I blew snow this week wide open that it started knocking and quit then upon restart it ran on 3 cylinders.

First photo is Kubota piston with 500 hours with the worn ring land. Second is two aftermarket pistons although dirty and hard to tell. Third is the one that seized.

View attachment 635598View attachment 635597View attachment 635599

I have never rebuilt an engine, but this seems to reinforce my parts buying theory.
If the needed part is internal to the engine or drive train, I will only buy OEM.
If it is a part that is bolted on the outside of the tractor, or the engine, I will buy from anybody.

 

[aeblank]

Even OEM, sometimes you gotta watch it..

Intake plenum on a 3.8L GM engine. Tons of problems, replaced, etc. Still leaked coolant. Got an aftermarket one with glass filled plastic, steel inserts in "critical" locations, and half the price.... Never another problem.

But in general, yeah. Add starters and alternators to the OEM list....

 

[LouNY]

Even OEM, sometimes you gotta watch it..

Intake plenum on a 3.8L GM engine. Tons of problems, replaced, etc. Still leaked coolant. Got an aftermarket one with glass filled plastic, steel inserts in "critical" locations, and half the price.... Never another problem.

But in general, yeah. Add starters and alternators to the OEM list....

Nope DB Electric,
also I've built many different engines mostly gas with almost all aftermarket parts,
the diesels I have done have been predominantly aftermarket usually the "in frame kits".

 

[fried1765]

Nope DB Electric,
also I've built many different engines mostly gas with almost all aftermarket parts,
the diesels I have done have been predominantly aftermarket usually the "in frame kits".

I would have to disagree.
New aftermarket clutch in my Ford 1920 lasted 2.5 hours.
Good experience though....I suppose?
2nd split was easier than the first.

 

[LouNY]

I would have to disagree.
New aftermarket clutch in my Ford 1920 lasted 2.5 hours.
Good experience though....I suppose?
2nd split was easier than the first.

And I've gotten a few thousand hours on clutches and not a one has been oem.

 

[The Fred]

I've been in the car fixing business 50 years last August, lots of pretenders selling their wares especially now online.

Rest assured I bought these parts from a well respected Kubota engine parts vendor. When I get time I will clean these pistons and measure them then place them in the wife's oven ( I know right?) and measure them again.

I want to think that there is nothing wrong with them but when I see anti-scuff coating gone in 3 hours running time I think this company needs to look at their production process or who builds their product for them. My gut says Chinese junk on these parts.

I've had lots of engines apart over the years, mostly Euro cars and some Japanese engines, a few LS GM engines (great product by the way) and have never seen the coating removed on any of them.