8011 back engine seal

[lwalsh2]

Hi, the back engine seal on my 8011 is leaking engine oil, we dismantled the tractor only to find that it is fitted with the early type seal which consists of a steel ring /oring and splash plate, everything looked ok but we fitted a new steel ring/ oring anyway,on reassembly the problem is still the same leaking engine oil, there is a slight blow in the engine which is probaly not helping, the new type seal is not compatable with this cranksaft either, any ideas to help wit this problem gratefully recieved ,
L.

 

[hve]

Check the Breather is not blocked with soot from the blow-by.

Any, and i mean ANY blow-by will make a labyrinth seal leak oil, if not well vented.
The Factory breather pipe is quite small, you could add another breather to help reduce the pressure in the sump...... either in the other "Side plate" , or in the Rocker Cover (i think the the 3Cyl UR1's had a breather in one rocker cover, this cover will fit all UR1's, but not sure about Cristal.

Other possible cause of Labyrinth seal leaking is Worn main bearings,..... was there any sign of ware on the old labyrinth? if so the main bearings need looking at as there should be no contact between the labyrinth and the crank if the bearings are holding the crank properly centered...... Main Bearing clearance should not exceed .003" (or 0.12mm).

As a last resort, plumb the breather back into the intake manifold (between the air filter and the engine) this will help evacuate the fumes from the sump (and re burn them), but be sure to fit an oil separator in line to prevent "runaway" if too much oil is sucked in!!!!!!!!!!!

Use all 25mm plumbing in breather to minimise restriction to flow.

 

[lwalsh2]

Thanks for the info I suppose that the real problem is the blow down on the engine and not the seal and a recent refurb of the head has only compounded the problem, so extra venting may help in the short term but it seems that the cure will be pistons and liners ect.

 

[hve]

Depending on the history of the tractor it might just need a good workout to unstick the rings. Zetors get fumey when only lightly worked. It is uncommon to find them worn out at less than about 10,000hrs. Renze may wish to expand on this topic

 

[dave_peters]

we have had Crystals that almost needed a silencer on the breather the blowback was so bad, but the crankshaft seals didn't leak, so the crank seals need examining, also as already said, the crank bearings need to be good, and one other problem we have come across was where an operator kept his foot on the clutch too much was that the thrust bearing either side of the main rear journal was badly worn allowing end float of the crankshaft, check it with a bar on the front crank pulley. That tractor had nearly 4mm slack and the bits of the thrust were worn down to the steel. that one was fixed as a budget repair by buying the thickest shims Zetor could supply at the time and carefully filing them down with a die grinder to fit the wear on the crank. The repair had done a further 2000 odd hours by the time we sold it and was still OK.

 

[lwalsh2]

The later type seal is more robust and is not affected in the same way as the earlier type either by blow down or slight shaft movement.