Blocked diff breathers

[steveG]

Changed the oil in the rear diff on my county last night, and had to do a 3 hour return trip on the highway today. When I got to my destination and went to open the rear door it was covered in oil spots.
Oil was leaking badly out of the pinion seal - bugger.

Hopped on here to find out what was involved in changing the seal, and one of the things that repeatedly came up was "check your diff breather".

Sure enough, when I blew down the end of the breather - completely blocked.
So I removed the banjo fitting and find this:

https://www.aulro.com/afvb/images/imported/2010/06/605.jpg (http://www.aulro.com/app/showphoto.php/photo/17826)
https://www.aulro.com/afvb/images/imported/2010/06/606.jpg (http://www.aulro.com/app/showphoto.php/photo/17827)

Completely blocked with crud.

Cleaned it all out, refitted, and tested again by blowing down the end of the breather. Still completely blocked.
Turns out there was about 300mm length of tube that was blocked with mud/gunge - in the low point where the breather runs down the chassis rail and then up to the upper suspension arm and diff. The breather only went to the top of the chassis rail above the axle.

I had some irrigation tube left over from when I extended the breathers on my D1, so just ran a complete new line and extended it up into the rear toolbox through the taillight loom grommet. No more mud in it now!!

Just hoping the oil stops coming out the pinion seal now.

Is it only the crud coming in the open end of the breather that causes the banjo fitting on the diff to block?
Also - is it worthwhile fitting some sort of little filter to the end to stop dust getting in, or is that really a "my diff breather cost more than yours" sort of thing?

Steve

[harryj]

Hi Steve, yes it is worthwhile and only a couple of dollars each to fit a disposable clear plastic see-through type petrol filter to the extended tubes of each diff breather.
Interestingly, I bought a couple of new shiny brass diff breathers for my S2A ex-mil, but they don't breathe at all (may as well be blocked). Puzzling.
p.s. Good detailed photos
Cheers, Harry

[disco2hse]

You still need to check them. They can still get blocked because they suck in dust that gets glued to the pipe walls from the oil particles that are released when the oil heats up and the air expands into the pipe - carrying the oil with it. You can actually get filters for the ends of the pipe but they are quite expensive for what they are.

[isuzutoo-eh]

I've sold a few petrol radio control car air filters to people wanting to fit them to diff breather lines. Pretty pink and blue bling :)

[steveG]

I've sold a few petrol radio control car air filters to people wanting to fit them to diff breather lines. Pretty pink and blue bling :)

You mean the coloured rubber outer ones with the foam filter in the middle that you get on small nitro cars?

Steve