Diff breather redux

[Slainte]

I posted this question in the Stock Alpine section, but I received little response (Thanks, Tom!) While I know there's a good bit of crossover readership between stock and modified, I thought I'd take a shot at asking the purely modified folks. Why am I getting enough back pressure to blow oil out the top of the diff?


"I'm having a bit of trouble solving a leakage problem in my SV differential. I believe I've located the leak at the breather on top of the casing. I've removed the crimped cap, but am unsure how to proceed. There is a small structure in the vent stack which moves back and forth quite freely. The top of his structure has a handy little loop in it, as if it should be pulled or pried. I am hesitant to do this with too much enthusiasm. I've not found any reference to this in the WSM, nor can I find significant discussion anywhere on the forums. Thanks in advance for any information you can send my way."

Ryan

 

[twospeed]

Is your breather a bolt that holds the "pig" in? I took my breather bolt off to look at it for you and found nothing under the cap, just a hole.

 

[Slainte]

Thanks for going to the trouble of looking! No, my breather sits toward the top of the pumpkin; it's a small metal cap that covers a tube with a loose loop of metal inside. I'm not sure how it works as a breather, and I'm not sure why oil would spray up and out. I'm easily confused.

 

[Jim E]

Not sure this helps but... I had one with the breather missing so I tapped the hole and screwed a brake bleeder in the hole, after cutting the end off the bleeder, the end that screws in the hole. Then put a length of tubing on it and attached it to the underside of the floor.

 

[Tom H]

Ryan, On my diff the breather is loacted at about 10:30 (as viewed fom the rear). Is this about where yours is? If it it located higher up toward the top it might be a bit more susceptible to spray right off the ring gear.


Tom

 

[Armand4]

How much oil is coming out? Is this a situation where a little bit of oil is splashing out through the breather assembly as it gets churned around by the ring gear and diff, or is oil spraying out, as if it's under pressure?
I just rebuilt the rear end in my SII, and the breather is just a bolt in the housing with a hole drilled through it. There's some baffling inside the housing to shield the breather bolt, but oil is still splashing up there and a little bit is leaking out. I haven't done anything to fix this yet, but a friend suggested I attach a short tube to the breather. This would keep the oil from splashing out quite as easily, and the housing would still be vented to the atmosphere.

 

[Slainte]

Jim - I've been considering the tube solution, just to see if anything different might work. Maybe I'll yank out the whole differential and replace it with a nice 8 incher. Seems a little extreme, but...

Tom - My breather sits at about 1:00, looking at it from the back. Splash could be the culprit, but if that were the case, I'd expect it to be a more common problem. I think it's interesting that there is such a variety of breather placements on these cars.

Armand - I'd say I lose around three ounces per hundred miles. A little blow-by wouldn't bother me much, but this is quite a mess. There is a trail in the dust that leads from the breather, down the starboard side of the case to the bottom. While driving, the drip then blows off the diff case, lands on the spare tire well, and seeps up through the drain holes, leaving the spare sitting in a nice little pool of oil.

 

[ddonatimfs]

rear differential leaking slightly

related topic....I have noticed a few drops of differential fluid under the differential. My two questions are #1, what would make this leak. There are no leaking wheel selas, etc. I have not tried to tighten all the bolts, yet. And #2, hoiw do I check the fluid level and how is it added back in, if it is low. I did buy some real end oil; hyperoil. Thanks for any ideas. DD

 

[socorob]

I have a Nissan Titan and it has the cap with a ball in it so it's sort of a one way valve. There's a semi common problem with these getting gummed up and it causing the axle seal to blow. What some people do is take that fitting off and put a nipple in it and run a tube or piece of hose up to a high and dry location and put a little lawnmower gas filter on the end just to keep stuff out. I did this on my 8 inch in my alpine also. Just make sure you het a filter that's not directional if you go that route. It needs to breathe in and out.

 

[MikeH]

Is it possible that air flow across the top of vent when driving is atomizing the oil into a mist, like a spray gun?