question Zetor 4718 engine problem

[Gasper]

Hello everyone,
My zetor 4718 started spewing out oil from the exhaust today while doing some log splitting. It has been burning about a liter of oil every 10-20 engine hours for the past 20+ years. I wonder if it is suffering from the piston rings failure as it only has one cylinder affected plus a little bit of blow-by. The cylinder walls are worn as well ( no cross hatches ) and has a bit of a lip at the top. Or could it be the valve seals? Don’t want to spend too much money on it as all it does is log splitting, tedding and loading manure. Thanks for any advices.

 

[Joachim]

I think this could be due to coked piston rings from running for too long without load. The piston rings can then seize up and no longer scrape the oil properly.

Generally, you should occasionally put the tractor under full load to prevent this.

The lack of a cross-grind and the edge above the cylinder liner also indicate corresponding wear, which can also lead to increased oil consumption, but should also be detectable early on by slight smoking from the engine case ventilation.

In the worst case, it needs new pistons/bushings. Also check the valves and replace them if necessary.

 

[Gasper]

I think this could be due to coked piston rings from running for too long without load. The piston rings can then seize up and no longer scrape the oil properly.

Generally, you should occasionally put the tractor under full load to prevent this.

The lack of a cross-grind and the edge above the cylinder liner also indicate corresponding wear, which can also lead to increased oil consumption, but should also be detectable early on by slight smoking from the engine case ventilation.

In the worst case, it needs new pistons/bushings. Also check the valves and replace them if necessary.

Found that the oil control ring’s spring was broken at 3 different spots and the oil scraper ring has been turned upside down and the compression rings have been mixed up. The piston is also badly scored with a 5mm wide gash on the side of it. The cylinder sleeves are glazed but no deep scratches so i’d probably get away with it by just honing them. The engine is very tired but still had good compression. I am also wondering how to get the valve guides out as that may also be the cause of my problem.

 

[Renze]

Put it to work so the oil burns off.

I wouldnt mess with those rings and pistons too much, as new sets cost 55 euro per cylinder.

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