Front Brake Oil Leaking/Spraying

[Tomahawk]

My front brake seems to be leaking oil. After riding for about 20 minutes, I notice oil dripping down the right side of the bike under the right handlebar.. and the oil level has depleted quite quickly.

Any ideas on what is likely to be causing this? Any screws I should tighten, etc.?

(It's a ZX6, 2007 model. I can show pictures if it helps?)

[Nobby the Bastard]

Is it the brake or the fork leg?
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trevor saxe-coburg-gotha:"Remember this simple rule - scooters are for men who like to feel the breeze on their huge, flapping cunt lips."
Triumph Sprint ST 1050

[stinkwheel]

If it's coming from your braking system, it's brake fluid not oil.

Among other things, it'll agressively attack paintwork, plastic and some rubbers so if it's dripping down the side of the bike, you need to wash it off quickly with hot, soapy water. You need to do this NOW because the damage is already happening.

What to do to fix it very much depends on where the leak is coming from. You need to find where it's coming from ASAP and not ride the bike until it's fixed.

Most likely places for a leak are around the banjo fitting on the master cylinder and where the brake line attaches to the banjo fitting. The leak would usually be apparent when you squeeze the level (which pressurises the system).

At the most straightforward, it's started to leak round a sealing washer and the banjo bolt just needs tightening. I've never actually had this happen though. Once they are tight, that's usually it.

More likely is a split in a brake fitting or a failure of the join to the hose. These could abruptly go from a leak to a total brake failure so you need to get it sorted pronto.

When you say the oil level has depleted, what exactly do you mean? Where are you checking the oil level? Or do you mean the level of fluid in the brake master cylinder?
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“Rule one: Always stick around for one more drink. That's when things happen. That's when you find out everything you want to know.”
I did the 2010 Round Britain Rally on my 350 Bullet. 89 landmarks, 3 months, 9,500 miles.

[Tomahawk]

[Robby]

Are you competent with fixing bikes?

If not, get it fixed by someone that is.

Brake problems like this are rare. Banjo bolts very rarely work loose. Crush washers can fail if they are re-used, but they would usually fail right after being put together. Seals can split, but I've never seen it. Brake lines can split, but I've seen a lot of 30 year old rubber lines that are still fine. Banjo fittings can split, I've only heard of this once when someone used aluminium fittings which carried a prominent NOT FOR ROAD USE marking.

So your problem is not a routine failure. If brake fluid is leaking, it is usually because someone incompetent has worked on the brakes and broken something in the process.

[c_dug]

[Tomahawk]

OK guys, thanks for your help, and sorry for the delay in replying; I've been away and I wanted to take some pictures.

I think I misused the word oil -- it's probably brake fluid.

I've attached 2 pictures, one of them shows what I mean when I said the brake fluid level has depleted.

Also, I tried squeezing the brake and seeing what happens: It is definitely, leaking, I pointed out in the picture where it's dripping, although I couldn't find out where exactly it's coming from.

As for the cause, I had an accident a while ago where the bike went down on the right side and I've noticed this problem ever since.. So it's likely that something was damaged/loosened when the brake lever hit the ground. (Here is the thread for the accident: https://www.bikechatforums.com/viewtopic.php?t=308488 )

[c_dug]

That bolt has a sealing washer on either side of it. I'd initially try to gently nip it up to reseal it, don't overdo it though, at the risk of causing a whole world of worse problems.

You'll get a couple of new washers from any bike shop for about 50p, they usually chuck them in free if you ask nicely while buying brake pads.
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[Robby]

Get some new washers. As c_dug said, they cost the square root of fuck all. They are a standard size, so you just need banjo bolt washers or brakes washers, two of them.

You can change the washers without doing anything complicated. Undo the bolt, take off the brake line and washers, put on your new washers - one each side of the brake line - and tighten back up. Have a rag under the line when you do the job, some brake fluid will drip out and it damages paint.

Then top up the master cylinder reservoir and squeeze the brake until it firms up. This may take 5 minutes or so, it's bleeding the air out of the system. No need to open any bleed nipples, all of the air will find its way up to the reservoir.

More worrying is the question of why it is leaking. This doesn't happen under normal use, so it would suggest someone has had that joint apart already - maybe to fit new brake lines. The washers look original, aftermarket ones are normally copper coloured. Someone may have loosened the fittings or fitted new brake lines without fitting new washers. This means you could also have bad connections down at the calipers, so have a good look at them one the system is holding pressure.

I would not recommend just trying to nip up existing connections if you don't know what you are doing. Brake fittings are tight. Brake calipers are made of fairly soft alloy. It is easy to over tighten the banjo bolt and either snap it, or break the caliper.

For ultimate peace of mind (and what I would do in this situation) you could replace every washer in the brake system with a new one and tighten up the fittings to the correct torque - using a torque wrench if you don't have a feel for the right torque. You would need to bleed the brakes afterwards.

[Tomahawk]

[MarJay]

I don't think anyone has mentioned this yet but...

Don't ride the bike until this is fixed!
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Remember kids, bikes aren't like lego. You can't easily take a part from one bike and then fit it to another.

[Tomahawk]

OK, well as a first course of action, I took a wrench and just tightened the bolt at the bottom by about 1/8 turn, and it seemed to have fixed the problem. I squeezed the brake lever about 20 times, and not a single drop leaked. I left it a few days, and tried again, still seems to be OK.

Would you guys say this is safe to ride, or should I get it checked out?

By the way, the brake fluid level has gone significantly below the "low" line. I just bought some new Castrol brake fluid, can I just open the top and pour some in, or is there a procedure?

[Islander]

If tightening the union has stopped the leak then you're good to go.

No special method for topping up. Give the cover and reservoir a wipe with a clean rag to remove any external dirt, remove the lid and the bellows and top up. If you've been lucky then there may not be any air in the system but take it easy at first until you're happy that the brakes are working properly.

If the lever feels spongey then air may have been pulled into the system and you'll need to bleed it.

[Tomahawk]

[tom_e]

Make sure you've bought the right fluid before topping it up, it should say on top of your res what to use it'll probably be DOT4.
Just double check you've not picked up anything fancy like DOT5.1 as they don't play nicely together.

[Kickstart]

[tom_e]

[Robby]

[Tomahawk]

[Islander]

All you need to do is check that each banjo is securely tightened and has a copper washer on either side. Start at the master cylinder and work down to the calipers. Check for signs of cracking or chafing as you go.

[Tomahawk]

[Islander]

Here you go - you can see the washers as well.

https://www.4x4xplor.com/images/Goodrich-SS/TJ-SS07.jpg

[tom_e]

baring in mind if it's still using stock lines the washers will most probably be aluminium rather than copper.

[Tomahawk]

[Islander]

Depends on the way that your bike is setup but at a minimum, one per caliper and one per master cylinder.