11-07-2013, 10:01 PM
Brakes generally dont leak providing they are looked after but never underestimate maintaining your brakes because they could save your life!
There is only 3 points where the actual callipers can leak. The flexi hose, the piston and the bleed nipple. Hoses rarely leak unless they are damaged but as i quick thing, when ever you have the wheels off, check the condition of the hoses. They are the weak link in your system. If the rubber is perished, replace them! They aren't expensive and only a small job to change.
Next is piston seals. They can break down over time but rarely have i seen them fail on a 306 calliper. Generally they will week and give you plenty of notice (spongy brake pedal) before the seal failing completely. Again whenever you have the wheel off, check for wet callipers. If you suspect a leaking seal, get it changed!
Final and most common to fail is the bleed nipple and thats what im focusing on today with this guide.
The bleed nipple is as the name suggests. Its there to bleed the air from the system after work being done. All air should be removed as air is compressible where as brake fluid isnt. This is what leads to spongy brakes and lack of brake performance.
The nipple (as you can see in the below photo, albeit modified) is a standard bolt with a tapered head on the end of it with a hole that runs through the centre for fluid to flow through. The nipple seals by the tapered head sitting in a seat in the bottom of the threaded hole in the calliper. This closes off the hole through the nipple stopping fluid from flowing.
A big problem is if this seat is even remotely damaged, it will leak. Its a common fix online to wrap the threads on the nipple with PTFE tape. This WILL NOT work! Its not the threads that seal so dont waste your time! If the seat has been damaged by dirt getting in the bleed hole, or the nipple being over tightened (should only be nipped up to 6-9lb/ft) there is a few options.
Replace the calliper - expensive and possibly a waste
replace the calliper seat - only possible on some callipers. not 306 ones!
Recut the seat - Can be time consuming.
We are looking at the latter. To start, you want to find a old bleed nipple and file all the threads off like so
Next, get some fine grinding paste and cover the tapered head. jam the nipple into a 11mm socket (wrap it in tissue to hold it in) and put it on a extender bar. Place the nipple in the hole so it sits on the seat and twist left and right. Keep going for a few minutes and inspect (clean the hole out with a cotton bud). You want to be left with a smooth, pencil grey seat. if not, repeat. If so, clean out with brake cleaner and a cotton bud.
Now the next bit could go one of two ways. You could put the new nipple in, bleed it then find it still pisses out of the hole. If so, you need a slightly longer nipple (peugeot sell them at £5 each
) or it may seal perfectly.
I recommend cleaning around the nipple with brake cleaner throughly after bleeding then cover it in chalk or talcum powder and monitor over a few days. If it stays dry (might end up with some condensation but it will go orange if its brake fluid) then all good!
There is only 3 points where the actual callipers can leak. The flexi hose, the piston and the bleed nipple. Hoses rarely leak unless they are damaged but as i quick thing, when ever you have the wheels off, check the condition of the hoses. They are the weak link in your system. If the rubber is perished, replace them! They aren't expensive and only a small job to change.
Next is piston seals. They can break down over time but rarely have i seen them fail on a 306 calliper. Generally they will week and give you plenty of notice (spongy brake pedal) before the seal failing completely. Again whenever you have the wheel off, check for wet callipers. If you suspect a leaking seal, get it changed!
Final and most common to fail is the bleed nipple and thats what im focusing on today with this guide.
The bleed nipple is as the name suggests. Its there to bleed the air from the system after work being done. All air should be removed as air is compressible where as brake fluid isnt. This is what leads to spongy brakes and lack of brake performance.
The nipple (as you can see in the below photo, albeit modified) is a standard bolt with a tapered head on the end of it with a hole that runs through the centre for fluid to flow through. The nipple seals by the tapered head sitting in a seat in the bottom of the threaded hole in the calliper. This closes off the hole through the nipple stopping fluid from flowing.
A big problem is if this seat is even remotely damaged, it will leak. Its a common fix online to wrap the threads on the nipple with PTFE tape. This WILL NOT work! Its not the threads that seal so dont waste your time! If the seat has been damaged by dirt getting in the bleed hole, or the nipple being over tightened (should only be nipped up to 6-9lb/ft) there is a few options.
Replace the calliper - expensive and possibly a waste
replace the calliper seat - only possible on some callipers. not 306 ones!
Recut the seat - Can be time consuming.
We are looking at the latter. To start, you want to find a old bleed nipple and file all the threads off like so
Next, get some fine grinding paste and cover the tapered head. jam the nipple into a 11mm socket (wrap it in tissue to hold it in) and put it on a extender bar. Place the nipple in the hole so it sits on the seat and twist left and right. Keep going for a few minutes and inspect (clean the hole out with a cotton bud). You want to be left with a smooth, pencil grey seat. if not, repeat. If so, clean out with brake cleaner and a cotton bud.
Now the next bit could go one of two ways. You could put the new nipple in, bleed it then find it still pisses out of the hole. If so, you need a slightly longer nipple (peugeot sell them at £5 each
) or it may seal perfectly. I recommend cleaning around the nipple with brake cleaner throughly after bleeding then cover it in chalk or talcum powder and monitor over a few days. If it stays dry (might end up with some condensation but it will go orange if its brake fluid) then all good!
Team Eaton
1999 China Blue 306 GTi6 - Eaton Supercharged - 214.5bhp 181lbft
1999 China Blue 306 GTi6 - Eaton Supercharged - 214.5bhp 181lbft
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