I have never seen this before but can only think it’s from some kind of a chemical contamination, however has anyone ever seen a jelly like substance in a master cylinder before? This is a 1954 Hudson Hornet that I purchased a few weeks ago & has sat for around 8-10 years. It has a Treadle Vac power brake & while there are some brakes I’m not sure the power boost is actually working. Sent from my iPhone using H.A.M.B.
The 50's movie named 'THE BLOB' starred a very young Steve McQueen. Seriously, water contamination? How was/is your pedal feel?
I’ve only driven it once, but it didn’t feel great, kinda squishy & not giving me a good stop. As part of going through all the systems, I was starting on brakes today & promptly found the blob! It actually plugged up my harbor freight pneumatic brake fluid bleeder quite quickly.
Mixing dot 4 with dot 5? Silicone brake fluid will do that I've heard. It is a BIG no no mixing silicone brake fluid with anything else.
Below are a couple close up pictures of the jelly substance I just pulled out. I had read on an RV forum that it was fairly common occurrence when master cylinders were rebuilt as it was a chemical reaction from what was used on the rebuilding. I’ve no idea what was used on the last rebuild or even if it was a fluid contamination like a Dot 3 or 4 to Dot 5. It is the weirdest thing I’ve ever seen. I figured I would pick up a gallon of dot 3 or 4 fluid & hopefully get it all out of the master cylinder. Once the MC is completely clean then flush the heck out of the system with that whole gallon, just to be safe. From there I will have to see where the brake system stands & replace whatever I need to do next. Sent from my iPhone using H.A.M.B.
Looks like mixing dot 4 and dot 5 like 'lostone' mentions.. If the cylinder is reasonably new, it could be the rubber lube from assembly.. Water is absorbed (dissolves/mixes) in brake fluid up to dot 4 , so wouldn't show as a blob of jelly, whereas regular brake fluid and silicon brake fluid don't mix (here's where the blob appears) but still work ok.. I can see evidence of rust/brown amongst that blob, dismantle the cylinder, clean and inspect the bore and cups etc.. If it was mine, and the bore checks out ok, I would lightly hone and fit a new kit.
Sound advice! I was already looking around for a kit to rebuild the master cylinder & Treadle Vac power brake system. If I don’t find anything or if I decide it’s not something I want to do, it looks like White Post Restorations can rebuild it.
Is it the single bowl "jelly-jar" type of master cylinder?! I couldn't hep myself! Mixing the two types of brake fluid is my best guess too. Frome what I've read....that's what happens. 6sally6
From what I have read if you mix Dot 4 and Dot 5 it will gel up as per your picture. But just to confuse matters even further there is a Dot 5.1 that you can mix with Dot 4 as they are both Glycol based
They don't call the old single master cylinders fruit jars for nothing! It could be the old flexible brake lines/lining breaking down with age, remember brake fluid is corrosive. HRP
I agree. I think I would start out replacing all the hoses and rebuild all the wheel cylinders and the master cylinder. The only time I've seen this was shortly before the brakes failed. In that case, it was the rubber in the brake system breaking down. When I pulled the rubbers out of the wheel cylinders, they were real soft and squishy, and the cups were covered with this stuff. I only have Dot 3 fluid here, I work on old stuff. I would like to know if there was brake fluid in the system before it came to you, and if you added fluid to the master cylinder. If you added fluid, what fluid did you add? Gene
Ky. jelly where I live . There is never enough jelly in the damn little packs for my samich ! You have moisture contamination , from where you may never find it , sometimes it’s from hot brakes and cylinders , sweating . DOT 5 will fix you up , but may start leaks and pedal will probably feel different that alcohol based fluids .
Use a syringe and get out as much as you can from the master. some guys use brake clean or denatured alcohol to flush a brake system. I’m not keen on this with older system as you can dry stuff out. It does work really well to flush contamination out of a system , but you be the judge on if it will/won’t cause you more grief. anyways, brake fluid is cheap, just open up the bleeders and let gravity to its thing and push as much brake fluid as it required through the system until it comes out clean. Then bleed as normal and check if the brakes are good or not. definatly contamination but can be almost anything from water to grease to ......well gosh get your mind outta the gutter !!
A friend who’s a retired sae mechanic told me to use rubbing alcohol as it will dissolve the jelly & then I can use my pneumatic sucking type of brake bleeder to clean out the master cylinder. He was definitely right as it worked like a charm. After a couple washes of the master cylinder I let it dry & filled with some new Dot 4 fluid & bleed all the brakes, twice for good measure. I used about 1.5 quarts & she’s looking good. It’s late so I’ll test it tomorrow & see how they work. Sent from my iPhone using H.A.M.B.
Some brake rebuilders use a silicone lube and it looks like a jelly in the fluid. Used to see it in the master cylinders in mid-range trucks. If that's what it is, it's not a problem. However, since you recently got the car, I'd flush the system to be on the safe side. I used to teach and we mixed all kinds of brake fluids in clear jars as a show and tell piece. Most really won't mix other than DOT 3 and DOT 4. I don't remember seeing any of the mixed brake fluids having a jelly like substance drop out.
I was under the impression that dot 5 has a purplish bluish tint to it. I'd agree with moisture or chemical contamination though. if you have a livestock vet supply store close by you can get rubbing alcohol by the gallon for around 10.00 Or at least it was the last time I bought some. I'd at least take the master cylinder apart and clean it all with alcohol and then just use the brake fluid I was going to put in the system as lube for the cups. I've used that cup lube that comes in some wheel cylinder kits but still use brake fluid most of the time anyhow. It used to be that when you changed a system either way to or from Dot 3 to dot 5 or the other way it was recommended to flush the system with alcohol then put the fresh fluid in behind the alcohol. I think I have that in the Napa EIS notes I have out in the bottom of the tool box.
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