jelly like brake fluid ??????

[jerry]

after servicing the rear brake after the over heating problem I decided to flush and replace the clutch and front brake fluid with fresh Motul 600 Dot 4 racing High temp fluid .as rear

the clutch was flushed and refilled and repressured OK but when i started to flush the front brake it refused to flush at the bottom and all the fluids started to become all sticky and jelly like Huh??? Its not flushing out at all . the old fluid was castrol racing Dot 4 and is 2 years old the brake was working fine but the fluid had become discolored .......now i am not sure what to do .

The clutch and rear brake are fine .I have never seen anything loke this in 35 years of bike servicing

[Kato]

This is a classic symptom of mixing DOT 5 (silicone based fluid with normal Glycol or synthetic DOT 3 , 4 or 5.1 fluid. If this is the case then your brakes will need fully stripping, cleaning and ideally re rubbering.

What was in there before you cleaned them?

[jerry]

Old fluid was Castrol SRF DOT 4 as i said in first post, put in 2 years ago by me , before that it was whatever was in the bike from new ,

thats why i am confused no DOT 5 silicon crap near the bike ????

[Capo]

I'm not so sure that mixing the two fluids together would result in a gelatinous mass, theoretically it shouldn't. Rather I believe this to be a result of excessive contamination with water.

You need to remove all of it, flush using clean fluid bleed each piece of the circuit until the clean fluid is visible.

If similar 'jelly' was present in your rear brake circuit, then this was the cause of your loss of pressure.

I'd also make sure that the brake fluid available there is not old stock, and given the high humidity never use fluid from a container that has been opened for more than a day or so,

[luckylarry]

DOT 3 and DOT 4 are hydroscopic in that they will attract and retain water - water can over time get in to the fluids and as Capo says it's the most likely explanation - is there any rust in the reservoirs or calipers?. I'd also check the seals on your reservoirs and calipers to make sure there's no way there could have been contamination.

DOT 5 being silicon based doesn't attract moisture so it would be less likely to happen were you using this although of course there are other issues with this.

[Nickj]

You can mix DOT 3, 4 and 5.1 fluids BUT you cannot mix DOT 5 silicon mix with ANYTHING OTHER than DOT 5 silicon fluid.
glycol-based brake fluid, (DOT 3, DOT 4, DOT 5.1) really should be flushed, or changed, every 1–2 years. Many manufacturers also suggest periodic fluid changes to ensure reliability and safety. Once filled, moisture diffuses into the fluid through brake hoses and rubber seals and, eventually, the fluid will have to be replaced when the water content becomes too high.
DOT 3, 4, 5.1 are water miscible fluids and lubricants. They are also pretty effective paint strippers
DOT 5 is silicone fluid and the above does not apply. Silicone fluid should be used only to fill normal hydraulic systems (NOT ABS!!) and SHOULD NOT be used in systems that have been previously filled with glycol based fluid fluid. The reason being that any system that has used glycol based fluid will contain moisture, glycol fluid disperses the moisture throughout the system and contains corrosion inhibitors. Silicone fluid works differently by not allowing moisture to enter the system, but it can't disperse any that is already there . A system filled from dry or after a full strip and cleaning can be filled with a silicone fluid. The nice thing about silicon is that it does not require the fluid to be changed at intervals, only when the system has been disturbed for a component repair or renewal.
Silicon DOT 5 isn't a miscible fluid and is a poor lubricant which can affect the life of seals designed for use with 3, 4, 5.1. It is inert and doesn't damage paint.

So that's the basics, now on the mixing which is where the problems come in. If DOT 5 silicone is introduced into an brake system, the silicone bond with the sludge generated by gradual component deterioration and create a gelatin like jelly which will attract more crud and eventually plug up metering orifices in ABS systems or at worst case cause pistons to stick.

So If you have already changed to DOT 5, don't compound your initial mistake / cock up and change back to glycol. Silicone is very tenacious stuff and you will NEVER EVER get it all out of your system. Just change the fluid more regularly than you would have done normally, halving the intervals would be about right.

And thats it folks basically DOT 3, 4, 5.1 systems stay on glycol and you should never add silicon based 5 to them OR don't add 3, 4, 5.1 to a 5 system. It's why the caps usually say use X,Y or Z only because they know what will happen when you don't.

[genex]

Hmmm, I see your jelly brake fluid and I raise you my crystallised brake fluid!

Sorry, can't help with your problem but, as this thread demonstrates, brake fluid can turn into some weird stuff :)

http://img228.imageshack.us/img228/3974/img0422small.jpg

[Rally]

I totally agree with you there Nickj, just one thing you didn't say that is really helpful; If you mix DOT 5 with any of the others and leave them in the fresh air and you have a really effective glue! It is great stuff.
I once mixed them together as I had heard what you have just written in detail about and doubted it, thats how I know what happens. Don't for gods sake, do that in your system. :(

[Capo]

Take some DOT 5 and any of the glycol based fluids, mix them in a jam jar and shake, observe and you will see they will seperate out.

[Nickj]

Free glue!?!? gotta try that Rally.

Oh and I did forget something. Silicon DOT 5 is odd in another way, if you scoot down to your local bike shop and buy a pot full then ride home you need to leave it to stand for AT LEAST an hour, two or more is better, as it holds small bubbles really well. If not you'll blled the brakes and they'll feel OK, an hour later you'll have bubbles all over the place and instant spongy break
DOT 3 etc don't do this.

I done the oops mixed silicone with glycol. My LC brakes used to get some heat problems so I switched to silicon race spec fluid. I ended up stripping the system to components but stuck with the silicon.

[Nickj]

Take some DOT 5 and any of the glycol based fluids, mix them in a jam jar and shake, observe and you will see they will seperate out.

Agreed they will but that's a clean mix, add in some damp fluid which is inevitable with glycol and some of the usual gunge that coats the inside of the hydraulics system and you will get a jelly mix and apparently an excellent glue

[jerry]

No jelly in the rear brake circuit or the Clutch , I agree it must be water in the front circuit , i will flush the entire system out again with fresh Motul RBF600

[jerry]

OK all sorted completely flushed the front brakes 3 times with my BIG syringe sucking out the old fluid as I feed fresh in the top , the lever is now much firmer than before too which is good .
Just to sure i flushed the clutch and rear brake a second time same method , now all systems have fresh fluid throughout.

then went for a 60 mile test ride all is good also put fresh oil Motul15-50 synthetic and filter bike feels great