Leaky seals or normal wear?

[chapel gate]

it all just mixes back up when you go for a drive. the oil is still the part that does the lubricating, its just mixed with a thickener so it stays in place.

 

[kingtom]

absolutely mate, an axle strip is not something I wouldn't feel comfortable doing unaccompanied for the first time.

Maybe i'll pay a little more attention to @kingtom the next time he needs to perform a field repair at Lincomb

Thanks for the advice chaps, very informative as always!

@Rosy I wouldn't watch me to closely. Didnt exactly make it look easy that day. That half shaft was an absolute pig to get back in. Still haven't worked out why, though when I had it out again the other day slipped straight back in no bother

 

[StarCruiser]

This thread has made me take a look at my front diff oil today.

Oh dear!! Not so much oil as a greenish thick soup. I've absolutely no idea why my internal seals are leaking but seeing the oil /grease on the cannon balls makes me think that both sides are not sealing. So it looks like I did something wrong when I did the rebuild. It's the only explanation. Perhaps I tore the seals getting the half shafts back in? I can't imagine I did but hey, something made them leak.

Oil changed for now, so at least the diff has a fighting chance. I'll get the bits together for another rebuild.

 

[chapel gate]

This thread has made me take a look at my front diff oil today.

View attachment 123729

Oh dear!! Not so much oil as a greenish thick soup. I've absolutely no idea why my internal seals are leaking but seeing the oil /grease on the cannon balls makes me think that both sides are not sealing. So it looks like I did something wrong when I did the rebuild. It's the only explanation. Perhaps I tore the seals getting the half shafts back in? I can't imagine I did but hey, something made them leak.

Oil changed for now, so at least the diff has a fighting chance. I'll get the bits together for another rebuild.

Were your half shafts worn where the seal sits?

 

[Chris]

When you did the rebuild, did you put a 'wash-out' oil change through the diff afterwards? I do that if I build an axle where the seals have gone. There's usually enough contamination in there to mess up the new oil. I new jack up one side and warm the axle tubes to get old crud to run out into the pan, then jack the opposite side and do the same. it's remarkable how much steeled crap comes out

 

[frank rabbets]

Sc did you use genuine seals ?

 

[StarCruiser]

Genuine seals. No appreciable wear on the half shafts. Manually cleaned out the axle casing and washed out the diff in a parts washer. Seals installed the same way round as those that came out. Metal ring to outside. New CVs, new needle bearing spindles. All genuine.
Don't understand it.

 

[Towpack]

As Chris said, the diff casing will need flushing. When I did mine a refilled initially with some cheap diff oil, did around 50 miles, drained and repeated and then did a final refill with an oil I was going to leave in there. The first flush came out almost as bad as the original stuff contaminated due to bad seals. The 2nd was much cleaner with just a trace of the moly. The final fill nailed it.

Edit...Just remembered that when I did mine the spring behind the lip in one of the seals came out and fell inside the axle tube when I pushed the half shaft through. It just didn't feel as tight as the other side so closer investigation found the spring. No idea why/how it happened though.

 

[chapel gate]

There is the theory of blocked breather, overfilled knuckle forcing grease past the seal.

 

[Chris]

Errm, what do you mean by metal ring to the outside? Do you mean the flat face of the seal, or the cupped inner bit with the spring? I know you won't have put a seal in backwards Rich, but it was a curious comment to have made.But then it's a curious issue too isn't it.

 

[StarCruiser]

CG, two things that have nagged me. I may well have been a little over enthusiastic packing the knuckles. I would say they were 3/4 full at least. I used probably 2 1/2 kg of a 3kg tin. I remember reading afterwards and thinking this might be too much.
Breather, err, well, I meant to do it…but didn't. However, I pulled the breather off yesterday, cleaned off the pipe and blew through it which resulted in some little pressure followed by release. Sucking gave a tight seal with no air entering.
Front axle, auto box and transfer box breathers now extended through filters and tied up high under the bonnet.

Chris, I should have said spring side inwards I suppose as that would have been clearer.
Metal ring as below, was fitted to the outside. You are right, I wouldn't have fitted a seal the wrong way round but if someone had done before and I copied it…, hence me fishing for reassurance.

 

[StarCruiser]

So, plausible causes,
1, spring(s) displaced.
2, overpacked knuckles.

A borescope camera could see the spring if the axle were drained and I guess the grease would find its own level if I changed the oil a few times and wiped the balls .

 

[frank rabbets]

I have a theory that the knuckles and hub assys are fairly airtight as any air gaps are sealed by grease but I have not got around to putting a T piece on with air line and gauge to check holding pressure. If they are airtight heat from braking might force grease past the seals but a seal would pop first wouldn't it ?

I put 2 tubs of grease in each side when I rebuilt mine.

I did not have much dif contamination. I bought the 80 with 30k miles on the clock and on checking the dif oil found the front was very milky c/w rear. I changed front dif oil every 24k miles and noticed it was more cloudy each time.

Greasy axle tube might well be your answer Rich.

 

[Chris]

I'm not sure that over packing the knuckles leads to this Rich. CV grease is highly immobile and if there was a bit against the seals, which there always is, then once that bit had gone, it wouldn't really be replaced. People talk about topping up etc, I did a decent job building mine up and after 9k miles had to pull it to drop the front diff due to the bearing being buggered. The grease I put in was in pretty much the same place I left it. You can squeeze grease in through the port in the top of the hub, sure and where does that go exactly? Not in the CV that's for sure. It might fly around and stick to the outside, but largely I think it's a waste of good grease. Built and packed well they should last the duration. They look awful when people strip them out, because there has been a failure and oil has got into the hub. If that doesn't happen, all should be good. Now, you've have an early failure of some sort. Grease may have gone one way, but has oil gone the other? Sooner you know the less mess there'll be to sort out. As to them being 'airtight' Frank, it's an interesting point but I think in truth they are more sealed against ingress than they are airtight - ie able to maintain a differential pressure. As far as I can see the grease in the hub (not the CV) is there to fill the void with something that stops water in particular from getting in. If there were no grease, water would get in and then probably drain back out again leaving rust behind. The grease simply prevents that. The hub as we know doesn't actually come to bear on the cannon ball at all. So it's not a lubricant.
Personally I think that grease gets past the seal mainly by being tracked through. The shaft moves back and forth through the seal and each time it does so, especially if there is wear, pulls small amounts of grease with it. But they are quite small amounts.

What was surprising is how tight the seal is on the shaft. I have played with worn seals, new seals, worn shafts and good shafts. You can't feel how tight they are when you slide the whole driveshaft in, but on the bench it's a different matter. They are pretty tight! Try it.

So Rich, I agree with Frank that there could have been stuff still in the tube even after cleaning and also that you might have had a spring failure. But I don't think that over packing is the cause.

 

[frank rabbets]

When you turn the steering doesn't the inner shaft move off centre ? Perhaps that's why the "good" seals incorporate a bellows rubber that seals the shaft but also seals if the shaft moves around. Normally with a shaft seal the shaft should be spinning true and a stiff sideways seal will do. Just a thought, not anything to do with your failure.

 

[StarCruiser]

I agree Frank. The seals do allow for lateral movement hence the bellows and yes, the shafts do move around a bit.

As for grease left in, I would have said not. I mean, that what came out wasn't just coloured but the consistency of medium porridge. Not grease, but not EP80/90 either. I did give what I could reach a darn good clean out but I guess without flushing there could have been some grease left but I wouldn't have thought much.

Really, I guess, what we are pretty much all saying is to suck it and see? Leave this oil in there and check it after, say, 1000 miles?

 

[frank rabbets]

I think that's best Rich. Perhaps the axle tubes, being horizontal, may act like a trap with not much drainage and the stiffer more contaminated stuff stays there.

 

[Chris]

As the axles have an oil retainer ring up near the seals, it's very hard to clean the axle tube out fully.

 

[StarCruiser]

As the axles have an oil retainer ring up near the seals, it's very hard to clean the axle tube out fully.

I do remember seeing that at the time. But seeing as it was January and piggin' cold I probably got as far as I could and left it there.

TBH I was kind of hoping that overpacking was the cause as the knuckles are a bit gooey around the base and got that way soon after I did the rebuild.

I'll clean off and see what happens.

On the air tightness front, there was a notable release of air on removing the breather, but as I say it wouldn't hold much pressure as the breather let go with me blowing through it.

 

[Chris]

Ahh but that is pressure in the axle Rich, yes, but not the hub. The axle does pressurise no question. And when it does it tries to push oil into the hub. When it cools again it may well pull grease from the hub. But that seal is on the inner seal and the shaft. The hub itself is very unlikely to be able to hold pressure.