Axel oil pressure

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HeywoodFloyd

HeywoodFloyd

Active Member
Posts
273
Location
Essex, UK
Ok so I had a Leak on the rear diff pinion seal. Figured it was the breather, but I was able to blow down the pipe and hole into the axel was clear.

But then the leak stopped. For a while. Then one day boom, oil ejected out of the seal in every direction.

So, I changed the pinion seal. All was fine on the first drive, no leaks. But today, I've just got back from a drive to discover a fair amount of oil coming from the center hub on the outside of one of the back wheels.

This can't be a coincidence. I'm now assuming that replacing the pinion seal means it's no longer the point of least resistance when the pressure builds up, so the new route out, is the wheel.

So why is the pressure building up? The breather pipe seems OK to me... do I need to be more scientific than just blowing down it?

Could this be something else?
 
After all, they tend to go at around about the same age . . . . if one's gone then it might be time to replace others. It's a good opportunity to fit new wheel bearings as well.
I had some excess oil exuding from the hubs and got the biggest improvement from replacing the little seal that goes between the stub axle and the main axle casing. It keeps the diff oil out of the hub. The one on my rear passenger side seemed to have given up completely.
 
I always thought the standard breather was a one-way valve designed to let air out of the axle, not into it? This would allow it to de-pressurise, or rather, not pressurise at all. The fact that you blew into it may mean you actually increased internal pressure!! I could be wrong ...

Having said that I'd also look at the stub axle/half-shaft seal, once this has gone it's also my experience that others will also go within a short time, as @Brown just said .. :)
 
Paul D said:
I always thought the standard breather was a one-way valve designed to let air out of the axle, not into it? This would allow it to de-pressurise, or rather, not pressurise at all. The fact that you blew into it may mean you actually increased internal pressure!! I could be wrong ...

Having said that I'd also look at the stub axle/half-shaft seal, once this has gone it's also my experience that others will also go within a short time, as @Brown just said .. :)
Click to expand...

Haha no I didn't try blowing in the other end, I took the pipe out of the axel and blew in that end of it to make sure it wasn't blocked. Having said that, I'm not convinced it's any kind of special valve being used there.
 
I've not seen any valving in my axle breathers. There's a kind of clip in plastic connector that joins the tube to the axle casing but it's just a straight pipe as far as I can tell. No doubt someone makes fancy ones with valves in.
 
@Paul D,

The ones fitted to mine, ( which may not have been std....:oops:) were only std rt angled fittings, which replaces with std airline push fit fittings. NO internal valve in either of them.

Cheers
 
Paul D said:
I always thought the standard breather was a one-way valve designed to let air out of the axle, not into it? This would allow it to de-pressurise, or rather, not pressurise at all. The fact that you blew into it may mean you actually increased internal pressure!! I could be wrong ...

Having said that I'd also look at the stub axle/half-shaft seal, once this has gone it's also my experience that others will also go within a short time, as @Brown just said .. :)
Click to expand...
it doesnt have a valve
 
No worries, thanks for putting me straight! I know mine aren't 'cos they're not standard axle fittings, btu thought the standards might have been .. :)
 
Yeah, when I sat and thought about it I realised I was talking stupidly ... ;)
 
are you blowing down the pipe on its own or back towards the axle? it could be blocked where is screws into the casing, id remove it and have a good look there, maybe replace with some pneumatic 6mm push fit connections whilst your there. I cant understand why else it would causing oil to be pushed out other than what others have stated and the seals are all going at the same time.
 
There should be no pressure at all in the axle. The idea of the breather is to allow air to escape as it expands when the axle heats, then to allow air back in as the axle is cooled and the cooling air within the axle contracts..
 
wammers said:
There should be no pressure at all in the axle. The idea of the breather is to allow air to escape as it expands when the axle heats, then to allow air back in as the axle is cooled and the cooling air within the axle contracts..
Click to expand...
So why did I get an explosion of oil out of the pinion seal a while back? It was originally just dripping, but then one day oil had literally been splattered all over the underside of the car - I've now replaced the seal, and there's no drips or anything (which is when the oil leak from the dust cap started) - If the breather is clear, why am I still getting a large build up of pressure?
 
wammers said:
If the breather is clear you can't have a build up of pressure. Seals do fail they don't last for ever.
Click to expand...

Ok, let's just hope it's that then, I find it strange that the oil managed to get everywhere without excessive pressure though - unless it was just simply flicked everywhere by the rotation of the drive flange/prop etc.

The leak on my wheel stops if I park the landy on a slop towards the opposite wheel, so I think this is more of a result of dead seal this time, rather than oil being forced out of somewhere. It's easy to connect things in your head sometimes during the initial "now what?!" panic stage - which may after all just be coincidences and bad luck.
 
Right, I'm confused again - while waiting for time to replace the seals and bearings, I figured I'd quickly replace the leaky dust cap - I've got a genuine LR replacement, but when I look at my hub, it actually looks differernt to ones I've seen online while watching videos on how the change the bearings, etc.

Here's what mine looks like (image below), the cap's lip seems to be under the metal... do I need to take the whole face of the hub off, to replace it, or should I be trying to somehow prise the cap out using a screwdriver and push the new one in? I don't want to just hope for the best and try. If I do have to take the hub apart, will anything else need replacing as a result, or should I just be able to get away with opening it up, replacing the cap for now and doing it back up?

2017_04_05_12_57_26_1.jpg
 
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