Odd Brake issue

[robb4100]

Been sorting out some electrical issues so the car has been off the road for several months.

Upon initial start the brakes were stuck open (this has happened in the past after prolonged resting) and no travel on the brake pedal. With significant pressure on brake pedal it finally freed up but now it was stuck closed plenty of travel on the pedal- hard stop at the bottom.

I jacked up the front end and confirmed that both wheels are stuck, Opened the brake line and relieved the pressure and the calipers released so that was eliminated as the cause.

I then applied the brakes and again it did not release. I removed the Master cylinder cap and the calipers released.

Now for the really odd part- replaced the Master cylinder cap and now the brakes are functioning without issue?

Any ideas?

PO changed the fluid 10 years ago- so I know I need to bleed and replace the fluid. Should I rebuild the master cylinder at the same time?

Robb

[UAB807F]

My initial guess would be that the master cylinder has had sufficient movement to free itself enough to move as it should.

I'm sure the more you use the car the more likely it is to operate properly again, but personally I'd take the opportunity to strip it down, inspect and rebuild it with new seals. There might just be some corrosion on the bores after standing so long which will cause the existing seals to wear faster, and of course if I adopt true "doom-monger" style it will probably fail just when you least want it to....

Brian

[ricarbo]

In order to make sure all the pistons were properly free to move, I exercised them. I took one brake pad out, then pressed the pedal to move the wheel piston a good bit, then pushed it back, refitted the pad, took the other pad out etc..
You can have a situation where only one piston is moving, but the brake seems to work, because of the flex of the disc.
I forget now what the specified interval is for changing the rubber seals, but it's in the manual, I think, at 3 yearly.
regards
Richard

[Elan45]

Is your 1st cap painted? There is a tiny vent hole that might be "sealed" closed. You might try clearing it with compressed air.

Roger

[MyLotus]

Roger, what is 1st cap?

Alain

[PeterK]

I assume that Roger is referring to the master cylinder cap that you had on originally (the first cap mentioned in your message), and maybe was causing your problem through the small vent hole being sealed by paint (or dirt).

[robb4100]

Thanks Everyone,

I removed the fluid from master cylinder using this turkey seasoning injector. http://www.homedepot.com/p/Bayou-Classi ... 202552785#
the fluid was mostly clear but there was disgusting brownish sludge near the bottom...I cleaned the master with fresh brake fluid prior to flushing the lines.

Breaks are working well now but I think I still will rebuild the master cylinder. I ruled out the the caliper pistons when removing the cap released the pressure and freed the brake- was I wrong to rule out the calipers?

Thanks again

robb

[Morangles]

This is very interesting.
I have not used my Elan S3 much since the summer due to lack of time and the bad weather.
The brake pedal now almost goes to the floor when I start, although I can still stop.
Not really sure what to do, but it's probably not a good idea to drive the car.

[ricarbo]

My opinion is that you were wrong to rule out the calipers. I can see what you say could mean the master cylinder vent hole was blocked, but have never suffered that fault myself. Suggest you exercise them as I described, but consider replacing the seals if they are of uncertain vintage. That means master cylinder, calipers and servo, in my book. After 15 years off the road I had plenty of sludge, some of it green, and thought it was probably disintegrated rubber, although that is black. When I took it all apart, the rubber bits were all very crumbly but the metal parts weren't in a bad state, so I just cleaned it all up and fitted new seals. If there was rust or scoring of the cylinders or pistons, I would have bought new parts. I cleaned up the metal parts with some fine emery cloth, washed them off with brake fluid, then reassembled them using plenty of Girling red rubber grease. Took some time, but didn't cost much.
regards
Richard

[ricarbo]

Morangles problem seems to be very different and sounds like the small seal at the front of the master cylinder isn't isolating the reservoir as it should. So it's rebuild time again. I suppose the point is that this is dependent on time not mileage.
regards
Richard

[UAB807F]

Another observation to the mix.....

The last few times I've rebuilt calipers one thing I have noted is how the rubber seals have expanded and have been slightly larger than the new replacements. Taking a seal out and then trying to push it back did work, but it was noticeably more difficult to get back into place. They were also softer and led me to think that the rubber has absorbed a certain amount of brake fluid.

We all hear about changing fluid because it absorbs water but from what I see changing seals gets a lower profile. There are recommended intervals for changing seals if you look around, but I, in common with other folks, only thought of changing them when something stopped working completely.

If the absorption theory is correct, then that's simply down to time of exposure and not wear/heat cycles/fluid changes/etc. So I changed the rear caliper seals which I thought were ok (stainless pistons years ago, no obvious sticking and hence no maintenance ) and sure enough they were so bad one wouldn't go back in.

Hence if yours are 10yrs old I'd be tempted to change the lot.

Brian

[elansprint71]

If you have had the same fluid in the system for ten years, then the flexible hoses will almost certainly have decomposed internally and may have collapsed; renew them before driving the car, preferably with stainless braided hoses.

[robb4100]

Thanks Ricarbo- I will take your advice and use your procedure for "excercising" the calipers or may just replace the seals.


Elansprint- The PO already install the braided steel flex pipes.