question Zetor 7711 engine won't turn all the way by hand...

[PeterZetor]

Ok so my friend was driving 8 kilometers down the road to his buddy's farm on his 7711. Wide open just cruising along and about 500 meters before his laneway the engine went POOF ! Chug chug chug chug. And stalled out . He called me and I assumed he blew the engine. His friend showed up with a tractor of his own and pulled him up to the barn . I told him to turn it over by hand and see if it will go around a few times . It turns 3/4 of a rotation and then stops. Something is binding. He gave up on the the tractor as he has a newer working tractor so he gave it to me, in return I do the odd mechanical job to help him here and there. So I loaded it up on a flatbed and towed it home. Drained the oil and it had coolant in it . (Alot of coolant .) I took the valve covers of just to take a look and I can see the rear cylinder has a bent pushrod. I found an engine rebuild kit online for about $1000. But it doesn't come with push rods. I'm wondering if I should dump money into this engine not knowing all the extent of the damage. Or should I look into a used engine? Everything else on the tractor works as it should. I live in Ontario, Canada ( Carleton Place)I'm not sure where the best place to buy new or used engine parts . Any help would be appreciated. Thanks in advance

 

[Renze]

What most likely happened, is that your friend left the air compressor chugging against a blindcapped line. It slams the keyway in the compressor shaft out, behind which the fuel injection pump is connected.

You will most likely be alright with new pushrods and a new compressor shaft, if you probe the valves for proper sealing (not being bent because the piston only hits on the side, as in the middle there is the combustion chamber)

Only way to find out is to take the heads off and the pistons out, to check for bent valves or connecting rods.

 

[PeterZetor]

Thank you for your quick response. I'm not sure what you mean about leaving the compressor chugging against blind capped line. Is there a way I can check something to see if it's in the wrong position? I will be bringing it into the shop next week for closer inspection/ disassembly. I will post my findings and progress .

 

[Renze]

The compressor is engaged by lifting a 90 degree bent wire up, the pushing a knurled lever towards the front of the engine.

If the air outlet line is blindcapped and the compressor engaged, it will wear out the shaft key because force will exceed design specs by far. In a normal air brake system the compressor air will be dumped to the atmosphere once the air tank reaches the set pressure.

 

[PeterZetor]

I will check for these items thanks for the explanation.