L5450 Front Axle Bearing Case Oil or Vent Hole Position

[5450nz]

I have stripped down the left front axle of my 1991-1992 L5450 to fix a persistent oil leak from the usual spot at the main king pin oil seal. In my case, the oil has been leaking badly out of the front differential, but not from the front bevel gear case.

I assumed that the oil seal located in the bearing case (item 030, page T082 of my parts manual) was also part of the problem so I have pulled this item off the diff housing....

The actual problem I have is that the small hole located on the outer ring of this block was located at the BOTTOM position when I pulled it off the tractor. This hole is drilled all the way through the block, and, if located at the bottom allows a free flow of differential oil directly into the bevel gear case. This makes the oil seal above it completely ineffective which has raised some questions...

The interesting thing is that this bearing case block can be rotated 180 degrees and fitted with the hole at the top, above the oil seal and would make more sense if it was actually a 'vent' hole to equalize the pressure between the differential housing and the bevel gear case rather than an oil feed hole ???.

Does anyone know which way up this block should be fitted. My parts manual does not show this small hole on any diagram.

I purchased this tractor used with around 2000 hours on the clock and it looks as if the main king pin seal has already been replaced and I am now suspecting that the bearing case block has been fitted upside down allowing differential oil to flood the bevel gear case ?

So the main question is: The small hole should be at the top because it is a vent hole, or, the small hole should be at the bottom because it is an oil feed hole ?

Image attached (see small hole right side block)...

Cheers
Paul

 

[5450nz]

After some further research and acquiring a copy of the workshop manual, it appears that the hole should be at the bottom of the block because the differential oil is used to lubricate the upper bevel gears inside the bevel gear case. There is a small 4mm seal with the roller bearing just above the lower bevel gear.

This is the point where the front hub oil is separated from the differential oil. (I was assuming the differential oil was terminated at the axle shaft seal but this is not the case.)

It still seems to make the bearing case seal redundant because diff oil simply fills the bevel gear case through the small hole.

 

[JoeBuyer]

I have not had a problem with my L5450 front axle but mine was made at the end of the run (original owner bought in 1999, so it was likely a 97 or 98 whenever it was last made). Plus I am only at 260 hours. I am looking forward to seeing what this turns out to be.

 

[JoeBuyer]

Rbargeron is the resident expert on L5450s. You might want to send him a message if he doesn't see this thread.

 

[5450nz]

Thanks Joe, I might PM the expert.

After putting the front axle back together, I'm again confused about the location of that small hole through the axle bearing housing. The filler plug for the 'hub' fills the main wheel case housing on the left in my picture but with that small hole at the bottom of the bearing case, then oil from the wheel case can flow back into the diff and the diff oil can flow into the wheel case. It just does not make sense to me. I am again thinking that the small hole should be at the top and that it is actually a 'breather' hole to equalize the pressure between the hub and the diff housing ???

This hub seems to have been worked on in another life. I think it has had the primary king pin seal replaced at some stage in the past. The main fact that I can't get past is that I have been losing oil from the diff, via the large kingpin seal. With the small hole at the bottom, that seal in the bearing case does nothing.

 

[rbargeron]

I dunno.... I have always known the whole front axle uses the same oil type - didn't know whether the three volumes where strictly separated.

That block in the picture is a spacer that lengthens the front axle on the larger L3 models (L4150, L4850, L5450). It isn't used on L3350, L3750 or L4350. Unfortunately I don't have an answer on why the oil seal is there. On the models that don't use the spacer there are oil seals in each end of the main center section - I don't know if these have a weep hole. It looks like the design intends to somewhat separate the three oil volumes. I wonder if allowing only restricted communication insures that, during operation on slopes, the oil doesn't immediately drain away from the high side kingpin?

 

[5450nz]

Thanks for your comments. I have been assuming that the designers intended to keep the three front axle compartments separated but as you stated, this may not be the case. Maybe the axle oil seal is simply there to slow down the oil flow on slopes as you explained.

Anyway, I have put it back together the way I found it so I'll see what happens after a few hours use.

Thanks for your input. Cheers Paul