I recently bought a 76 that was supposed to have had a brake job.
The brakes were spongey from the start and started pulsing after 500 miles.

I checked the brake fluid and found it low and the rubber cups sucked into the master cylinder. I topped it up and went for a drive.

When I returned I found dirt in the master cylinder.

The work that was supposed to have bee done was...
- New Brake Master Cylinder
- New Front Brake Calipers
- 2 Rear Rebuilt Calipers
- 4 Machined Rotors

Does anyone have any thoughts on this.
Thanks in advance...

Master Cylinder

 

The master cylinder does not look good. Is that rust? Looks like rust. Also you said the brake petal had a pulsating feel. Actually, this is an indication of an out of round rotor or a bearing problem. Hopefully some other members of the forum will have a response, I think they know more about this than me.

The C3 brakes can be a bit of a problem, but once you get them squared away, they're petty good--at least for a few years.

 

The brown stuff is brake fluid illuminated by my flash.
I replaced the pic with a higher res one.
Might be easier to see.

 

That looks nasty to me. I'd flush the whole system. Also, brake fluid doesn't just evaporate from the system, if the maser cylinder was low there are only a couple of possibilities. One is that you have a leak. The other is that it wasn't filled enough. The last is significant pad/rotor wear.

The brake pulsing is usually a sign that the pads didn't bed in correctly. Contrary to popular belief, rotors don't often warp. I always believed they did until very recently when I was pointed to a couple of articles at some stoptech website (I can look them up when I get to work as I bookmarked them if you are interested). What usually happens is that the brake pads leave deposits on the rotors unevenly and this will cause a pulsing in the brake pedal. It can be fixed a couple different ways depending on how bad it is. In the most recent case I had with our Camry (it had less than .002" runout when I measured and the pulsing was unbearable it was so bad), I had the rotors turned and replaced the pads. Problem solved. To help ensure the pads bed in correctly you should accelerate to 60 MPH and then brake with 80-90% braking force (hard) down to 5MPH (don't stop!) and then repeat for a total of 10 times. You will get a brake smell and what seems like brake fade, just keep it up until you've done it 10 times. This procedure can sometimes even fix the problem without going through the rest (resurfacing/replacing the rotors and new pads) if the pulsing isn't too bad yet.

-dath

 

I'd use a baster to suck the garbage out, then flush it.
I hate to pump that stuff through my system if I don't have to.

 

Touch nothing. Do not attempt to remedy the situation. Contact the shop that did the work asap - you have some warranty work for them.

Mess around with it and you will muddy the waters, making it more difficult to find the problem + you will likely void the warranty.

 

Poor job there, my bet is they didn't flush the lines, if it's that bad in the MC there's a lot more lurking in the lines and the calipers. Have them redo it.

 

Looks like they replaced everything but the old rusty brake lines...then didn't flush the system once new components were installed. If your not taking it back for warrenty...flush the entire system repeatedly with denatured alchohol...or replace all the lines.
Eddie

 

Had my brake fluid do the same thing, mine was caused by (i believe)using synthetic brake fluid. drained and flushed out the system again, put in DOT3, no issues

 

Most people think brake fluid lasts forever, it doesn't.

You should be replacing the fluid at least once a year, more if you race. the easy way is to remove the fluid from the MC and just add fresh stuff, that will help a lot. Turkey baster Mity vac.. remove it all and clean the MC then add good clean Castrol Synthetic

In your case I'd then bleed all the brakes untill I get clean fluid.

Just don't pump the brakes while the MC is empty!

It's better of course to completely flush it all out...

I would flush it myself, I wouldn't trust any shop, much less one that did a brake job that resulted in mushy brakes and dirty fluid.

What do you want them to screw up this time??

 

Might be Silicone Brake Fluid and rust.

From the photo it looks like the contaminate is not dispersing ,but is clumping and staying separate from the clear fluid. Regular (Dot3 or 4) and Silicone (Dot 5) do not mix.

I would guess that the car had silicone brake fluid in it before the shop did the work and also the lines were a little rusty on the inside. Like most brake shops (especially discount brake shops), They didn't check to see which brake fluid the system had in it. Then they put in the usual Dot 3 stuff. Once they finished, even if they flushed the system, there would be residual silicone fluid on the walls of the lines. I suspect that's where the rust coloring is from. This would evenually separate and float around in the system, possibly working it's way back up to the MC.

I'd say the system needs to be fully flushed and refilled. And the shop that made the mistake shold pick up the tab. Ask them if they checked for silicone fluid before doing the work.

 

"Contrary to popular belief, rotors don't often warp."

Whomever wrote/said told you that is full of poppycock.

Not only do they warp, they are often warped when brand new, right out of the box... even today... before they are ever touched by a brake pad. I check them myself with a dial indicator.... and I do a lot of brake work. No time to read about it while I 'm reading the dial indicator... accurate to .0001".

My dial indicator does not lie or spew poppycock.

I owned/ran my own machine shop.... and measured & turned more rotors than Tommy Lee has tatoos.

Rotors will also warp when they are too thin to dissipate heat. This happens when they are turned below minimum spec.... which is why they have a minimum spec in the first place... which any commercial shop is prohibited by law from violating. Otherwise they are liable in a court of law.

If you buy rotors from an autoparts store which has several different price ranges of rotors, take a close look at the thickness of the INSIDE platter... the cheap ones, although the same OUTSIDE dimension as the others, will have a thinner INSIDE platter.... or the web will be wider with thinner inside & outside platters... and that is why they have a lesser guarantee... they will warp sooner due to a lesser ability to dissipate heat. -Generally Speaking-

Before I started my own business, I worked in an autoparts store where I turned drums & rotors. Since the job was often delegated to the lowest man on the pole, I saw lots of mistakes. It was common for an improperly trained employee to attempt to turn a schoolbus drum without the proper added lathe spindle support. The whole machine would tip over and bend the lathe main shaft internally as well as the outboard shaft. All drums & rotors turned from that point on were lopsided, and it would be several months before the store owner(s) allowed us to repair the lathe ($$$). Poo happens.

I could go on, but life is short.

20 lashes with a wet noodle to the author of that poop.
I didn't even bother tracking it down. Don't need to.
35+ years of experience doing brake work professionally is nuff said.

NOT ripping on the poster.... ripping on the Beavis who supplied the supposed info.... whomever they is are was were.

Warped rotors is a very real and a very common problem.

 

First off, thanks to all who responded on my question of dirty brake fluid. I just bought the car so I don't have any bills or proof to take back to a shop. My feeling is that the previous owner did a lot of work on the car, but that he didn't put many miles on it to shake out the bugs.

I realized when I bought the car that there would be some work left over for me. After all, the car is almost 30 years old. Ive done a few brake jobs in the past, but not enough to learn the tricks that come from working on them full time.


Question to Tom454 (So that we may gain from your 35+ years)
I have heard that wheel nuts should be torqued down as uneven
torque combined with braking heat can warp the rotor. I heard that this is more of a problem in newer cars (80's & up) when the rotors were made thinner to save weight.

Is there any truth to this?

Thanks in advance.

 

I'm going to have to agree that it's the brake lines. They need a good cleaning or replacing. My 78 was in the same shape when I bought it ten years ago. I also have to disagree with the fellow who said that silicone brake fluid did it to his. When I bought my new calipers and rotors ten years ago from a local vette shop he gave me a quart of siicone brake fluid and it has been in the car for ten years. No problems as it will not absurb moisture. I had silicone brake fluid in my 48 Plymouth for over 12 years and no problems. That car had two wheel cylinders per wheel and I know the new owner is still using silicone brake fluid. I do know you can't use it on anti lock brake systems on new cars.

 

Tom454, I don't disagree from my previous experience, but I question the *REASON* why the rotors are "warped" I guess. There is a difference in a rotor that comes prewarped or has been improperly turned and one warping from heat. Also, does seeing runout mean the rotor is warped, not necessarily, it could be an uneven deposit of pad material. It isn't obviously visible when this happens (as with my Camry), but it *CAN* happen. .002" (as measured by me) is not a huge amount of runout and is within tolerance for that car. I didn't feel safe driving it with how bad the whole car would shake when braking from freeway speeds. Turned the rotors, put on new pads, problem was solved.

I admit, I don't have the kind of experience you have, but I found the information in the articles very interesting, and in my case, downright accurate to the problem I had. There are several interesting articles at the StopTech website:

http://www.stoptech.com/whitepapers/...otors_myth.htm
http://www.stoptech.com/technical/

I won't argue about this anymore as the articles do a far better job at explaining the point than I would and my knowledge isn't all first hand experience (which is very valuable). I do agree with what they are saying, but also, I would never say that a rotor will not warp, it just wasn't my most recent experience and I couldn't say from the previous times I've had issues as I hadn't discovered those articles until someone here on the forum recently pointed them out to me (saving my butt I might add as I was very skeptical that the rotors were at all to blame given the small amount of runout).

Tom, let me know what you think of the article(s) if you have time to read them. I really am interested in knowing more and since I don't work on cars for a living, this is my best source of information.

Regards,
-dath

 

I didn't think the silicon advise suggested that DOT 5 would cause rust, he said it didn't mix with DOT3,4 and might look like a oil in water.

I believe the rust color is just from light shining through the brake fluid.

 

Dath: Thanks for the links, I will review that article.
Tom : I will second Daths request for your opinion.
This is my best source of information too.

 

fresh brake fluid will turn brown from the mold release used when they mold the rubber brake parts. i have seen this even on my dirt bikes and quads as they have a translucent master cylinder and you can see the brake fluid turn dark

 

i bought a new 2001 in 2002 (sat on lot a year) no miles on clock....when brakes were applied, the steering wheel rocked and vibrated.warped rotors, the dealer replaced the rotors,problem gone

 

that is called "lot rot" caused by the pads setting in one place on the rotors combined with moisture.