Differential breather leak

[Zed Head]

Mine too is slowly covering the back of the differential housing with oil. Luckily, the dirt stops it from dripping on the garage floor. I wonder if a piece of sponge or cloth or maybe a plug of Scotchbrite might stop the splashing, but still let it breathe.

I've never had one off so don't know what's inside but have to assume that the leak is oil getting splashed up, probably in a fine mist form, in to the vent where it can then dribble out and down the differential housing.

[steve91tt]

That is an excellent idea! I'll give it a whack.

[Z train]

Steve-have you added anything other than the gear lube?

[steve91tt]

Steve-have you added anything other than the gear lube?

Nope, just redid the diff gasket and filled it up with gear oil.

[Z train]

Oh,well-there goes that theory.

[Pop's Z]

Isn't the arrow supposed to point towards the front of the car? That's how mine is on the diffy and the tranny. Filled correctly w/ RedLine 75-90 and no leaks. When I pulled my diify to replace it w/ a 4:11 R180 from a 200sx the vent was made of metal and the part inside the diffy was slanted towards the rear arrow to the front. Just my 2 cents.

Cheers, Mike

[steve91tt]

The vent is symmetric back to front so the arrow pointing front is the same as it would be pointing back.

[mgood]

Don't know if this helps, from me 76 280Z, my arrow point to the front.

[RIP260Z]

The vent is symmetric back to front so the arrow pointing front is the same as it would be pointing back.

The top of the vent tube is, but the bottom that sits inside the diff/gearbox, is not. The arrow on the top cover is meant to line up with the "cut away" side that is in the diff/gearbox. If this is put in wrongly, it would not matter how the top was put on. Have you pulled the tube that goes into the diff out?

Cheers

Ian

[Zed Head]

The minutiae is the most interesting stuff...

I think that there might be two different breather types. The text below is from the web link shown.

The breather on my car was pointing sideways. I think it may have "walked" its way around after a few million heat cycles.

http://www.carpartsmanual.com/datsunS30/PartNumberDetails/tabid/1848/Default.aspx?PartNo=38352-78600&SectionNo=088B&KeyNo=10

Section 88B Key# 10 Datsun 240Z/260Z/280Z Differential Gear, Pinion & Cover (R200)

38352-78600 BREATHER

Model code: C30-SUT

Newer part numbers:

Older part numbers: 38352-78500

Part No. Model Applied Date Qty Ica Superceded

From To N F

BREATHER

38352-78500 - 7510 1

38352-78600 7511 - 1 38352-78500

Edited January 5, 2011 by Zed Head

[steve91tt]

Have you pulled the tube that goes into the diff out?

I did pull the tube and I thought that there was a hole on either side of the bottom of the tube that line up with either end of the arrow, if that makes sense.

I'll pull the tube when I get a chance this weekend and flip it around so that the arrow points the other way.

[Zed Head]

Here is a picture of the breather vent from a 1976 R200. The screwdriver goes through the hole at the bottom. The stepped down portion is a press fit in to the breather hole.

Same effect, arrow pointing forward or backward. In general, I have found that arrows are usually meant to point forward.

There has to be some "breather vent install instructions" out there somewhere!

p.s. I crawled under my car and found that the arrow on that breather points sideways as noted above. I forgot to look at the one in this picture (it's a spare), I pried it out then noticed the arrow.

Bonus finding though - my fill plug could be tightened an extra turn and might have been contributing to the oily mess.

Edit - amusing coincidence - here's a 71 R180 with the arrow pointing forward, post #9 pictures (you might have to view it and blow it up to see it) - http://www.classiczcars.com/forums/showthread.php?threadid=40824

Edited January 6, 2011 by Zed Head