Oil leak from differential vent

[benjack]

Hi, Im hoping someone can kind enough to give advice.

Interesting new problem during the last race weekend.
I have a serious oil leak from the differential/axle vent/breather.
We had the diff out a while ago and also cleaned and repainted it at the time.
All I can think is we loosened or unclipped something at the time.

(we have checked and the propshaft and axle seals are good and not the source of the leak.)

Problem is - the vent is set into a metal frame and I'm not sure how to get in to open it, or how it's supposed to work.

(The little metal cap is loose - I'm assuming there should be some type of spring to hold it shut.)

Does anyone have an illustration from a workshop manual or advice on how to repair this?

Many thanks

[Thotos]

I presume you are sure you haven't overfilled the rear axle? The only times that I've seen these valves 'leak' is when the axle is overfilled. There's certainly no spring or anything fancy, it's basically an open hole to allow the axle to vent pressure. The cap is there to stop dirt getting into the axle.

[benjack]

Thank you for responding.


This is a standard 131 solid rear axle. 3.9 ratio with the centre welded.
Diff was filled to the botton of the fill bolt hole.
We had lost a worryingly large amount of oil through the breather, and needed to top up with about 300ml of oil to bring it back to the level.
The race track has 4 right hand bends. Breather is on the left hand side of the axle, and oil had run out the breather and along the axle towards, and onto, the left rear wheel.
No oil on the right hand side.

Are we overfilling? Not sure, but if to the bottom of the fill plug is incorrect - then you might have identified the problem.

[Thotos]

To the bottom of the fill plug with the car level should be the correct amount.... 

[TOAD]

FIX.

Remove the vent top and connect a length of oil resistant hose. Enough length to make a 2-3" loop and clip it to the underside of the body over the axle.  We never found a need to fit a bottle.

Axle will brake the teeth of the pinion so start sorting a new axle now before you waste a race weekend.
   The diff's are rubbish even for a road car.

Hope this helps.
Roger..

[benjack]

Roger

Thank you for replying.

That's exactly what we have done.
Seems to keep the oil where it belongs.
I'm still unsure why the diff started leaking though.
I ran it in the car for over a year without any oil leaking. Then took out the diff for one race weekent to try out an open 4.1 ratio diff.
Much worse than the 3.9 welded diff so we put it straight back in.
- and it started leaking-  :-(

We're working on converting a Toyota M75 LS diff for the car. 4.5 ratio and LS should really help around the track.
But we've hit a wall with rear brake calipers. I want to keep the fenders standard and keep using the 13inch wheels and tyres I have. Nothing we can find will fit into the rims.
Feeling a bit stupid for starting this conversion without thinking it through properly, and now seem to have wasted time and money.

All part of the fun i suppose.

[kev131]

Nice race pics.....shame about the race car number....out by 1!!  😕

Are you passing the Anglia on the outside or was he nipping up the inside? 😊

[benjack]

Fortunately I now have #131, but am holding it for the new race car we are building.
Hopefully there will be pics to show in the new year.

The Anglia runs in the Classics category, and is, despite a smaller engine, considerably quicker than me. I let him through.
The Escort behind me is more evenly matched and we have much fun on race weekends.

[TOAD]

Looks to soft on the rear, look at the front wheel starting to lift.

[TOAD]

How are you getting on with the car these days?

[benjack]

Hi
We ended up running a breather pipe from the vent up into the boot and looping it back out the rear.
This seemed to help.
But we have now put a new axle into the car with M75 LSD.
Some work still to be done but the car is about to be retired and put back onto the road.

Race car #2 is progressing nicely, and has now become the focus of our efforts.

http://131mirafiori.com/smf/index.php?topic=8216.0