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swebster · 08-28-2005, 10:33 AM

On our last trip I noticed the break pedal travel was getting a little longer than usual in our 345. Today was my post maintenance day so when I went to look for leaks and top off the fluid I was surprised to see what looked like amber colored, crystal, gooey things all over the master cylinder. I also found the fluid to be alarmingly low and a leaking fitting at the MC.

The gooey stuff cleaned up with a dry towel, but does anyone have ideas on what this stuff is? Is it an indication of a larger problem with the breaking system or fluid? It was limited to the master cylinder itself and there was some residue on the MC cover gasket as well.

As always...all ideas appreciated.

john hd · 08-28-2005, 10:38 AM

boiled over brake fluid?

john

swebster · 08-28-2005, 05:06 PM

John,
I don't think so. None of my recent trips required any significant braking nor did we encounter any really long downhills. I was looking at those headers and wondering about heat, but since the MC is forward of all but the #1 primary I didn't think that heat from the exhaust would be a factor.

This stuff looks like well....amber, more "crystalized" than "sappy". Is any of this making sense?

overlander63 · 08-28-2005, 05:18 PM

Quote:

Originally Posted by swebster

John,
I don't think so. None of my recent trips required any significant braking nor did we encounter any really long downhills. I was looking at those headers and wondering about heat, but since the MC is forward of all but the #1 primary I didn't think that heat from the exhaust would be a factor.

This stuff looks like well....amber, more "crystalized" than "sappy". Is any of this making sense?

Power steering fluid from the hydroboost unit? Dust has caused the fluid to clump into little dust balls.

john hd · 08-28-2005, 05:22 PM

what fitting was leaking?

brake fluid or power steering fluid? i think terry is on to something....

john

swebster · 08-28-2005, 07:45 PM

Well now I'm questioning it too. I thought it was the rear MC circuit given the amount of fluid missing from that resevoir and the amount of fluid below the MC. The really strange part is that is was only on the MC res....nowhere else. Seems like a leeking HB would be everywhere.

I have a bunch of inspections due so I'll pull the wheel and really get in there. It doesn't seem to do anything, but I don't like unkowns.

overlander63 · 08-28-2005, 10:15 PM

Quote:

Originally Posted by swebster

Well now I'm questioning it too. I thought it was the rear MC circuit given the amount of fluid missing from that resevoir and the amount of fluid below the MC. The really strange part is that is was only on the MC res....nowhere else. Seems like a leeking HB would be everywhere.

I have a bunch of inspections due so I'll pull the wheel and really get in there. It doesn't seem to do anything, but I don't like unkowns.

A quick and dirty way to check if it is brake fluid, or power steering fluid, is to put some water on it. If it is brake fluid, it will turn white, and wash off. If it is power steering fluid, it will shed the water, and stay there, with a rainbow sheen to the water that goes on the ground.

swebster · 09-11-2005, 06:20 PM

After many many delays, today was Airstream maintenance day. I removed the driver's side wheel so I could perform a compression check and get up close an personal with the MC "issue". I was shocked and frightened to find the forward resevoir completely empty with nothing but sludge in the bottom.

I removed the MC to get a closer look. Pretty sure the gasket on the resevoir failed and let it leak out. (that must be what the "stuff" was). Still can't figure out how the sludge got in there.

I don't want to take any chances so I'm off to the store to get a new MC. Bummer since this one is only a year old....also going to vacumm bleed the entire system, replace the fluid and replace the flex lines.

YIKES....I'm headed to Las Vegas in a couple of weeks in the AS and have been blowing this maintenance check off for weeks. I'm really glad I looked.

overlander63 · 09-11-2005, 09:39 PM

Quote:

Originally Posted by swebster

After many many delays, today was Airstream maintenance day. I removed the driver's side wheel so I could perform a compression check and get up close an personal with the MC "issue". I was shocked and frightened to find the forward resevoir completely empty with nothing but sludge in the bottom.

I removed the MC to get a closer look. Pretty sure the gasket on the resevoir failed and let it leak out. (that must be what the "stuff" was). Still can't figure out how the sludge got in there.

I don't want to take any chances so I'm off to the store to get a new MC. Bummer since this one is only a year old....also going to vacumm bleed the entire system, replace the fluid and replace the flex lines.

Steven, the gasket should not allow all the fluid to leak out like that, it is only supposed to keep fluid from sloshing out, and getting goop in the system. The sludge may be from failed rubber parts in your brakes, the front reservoir should go to the front rotors. Didn't you have all that stuff apart earlier, to pack bearings, etc? Is it possible you may have left a compression washer off a caliper? Maybe a line is leaking? Maybe a seal on a caliper piston?
Also, if the gasket on top of the reservoir is all gooey and swollen, you have big problems with your brakes, like you have oil in the system, and everything rubber will have to be replaced.
Sorry to be alarmist, but I don't want you to wind up halfway to Vegas, and have no brakes.

swebster · 09-11-2005, 11:19 PM

Terry,
Actually, I'm already alarmed so your post is perfect. I did look all over the front brake system and lines for signs of a leak but found nothing obvious. You are correct in that I repacked the front bearings but I had the calipers and pads replaced by the selling dealer way back when I bought the MH. So the operations where done at different times.

The gasket is not swollen or gooey. The sludge is in the bottom of the res. I had to cut the repair short today so I'll take another, closer, look tomorrow. I did run the MC down to my favorite AutoZone and talked to the manager about the crystals but he had never seen anything like it either. He's one of those parts guys who usually knows everything about anything I throw up on the counter so this was a rare occasion.

Planning new rubber lines and MC with a complete bleed this week. I like to do inspections and maintenace like this before I leave on a major trip (must be the pilot in me), but really did not see this coming. Kind of kicking myself for falling off the regular MC fluid level checks. Lesson learned.

I'll keep you up to date. If anyone can think of anything else I should check please chime in.

urbanextreme · 09-12-2005, 07:27 AM

is the sludge clear jelly looking stuff?

swebster · 09-12-2005, 08:10 AM

urbanextreme - no, it's more like sludge, fine particulate suspended in brake fluid. brown/grey in color. Thoughts?

Also - I took another look at the MC this morning and noticed some more of that crystal stuff on the nose of the MC. Any chance the hydro boost could be leaking into the MC (or the other way around)? I've not gotten into the boost system yet so I really don't know what I'm talking about here - just speculating.

87MH · 09-12-2005, 09:05 AM

Quote:

Originally Posted by swebster

..... Any chance the hydro boost could be leaking into the MC (or the other way around)? I've not gotten into the boost system yet so I really don't know what I'm talking about here - just speculating.

I had the MC on and off many times last year - I do not think there is a way for the HydroBoost fluid to get into the MC (unless there was a crack in the HB power brake unit) - besides, if the problem was migration from tne HB to the MC the MC would be overflowing with liquid.

The HB brake unit activates a separate rod (via a linkage), and that rod actuates the MC - there is no place that the HB fluid and the MC fluid could be in contact via leaking "O" rings.

From the description, I think the problem is within the brake system itself - MC dry with no observed leaks in the slave cylinders or the flexible lines -

Methinks the brake system is talking to you -

What would cause the Master Cylinder to "Boil Over" - and empty itself - I would think heat or the introduction of some sort of gas would be the answer. Is it possible that the fluid leaked from one of the Slave Cylinders (or one of the fittings - remember the front/rear brake system imbalance indicator (shuttle switch) hidden in the front crossmember).

It COULD be heat or gas from the hydroboost brake power unit itself.

My HB system has a small "Gas Reservoir" mounted on the rearward face of the unit. All of my documentation and service manuals say the same thing about the pressure reservoir - "Don't Mess With This". The pressure reservoir is aluminum, and sort of purple in color.

swebster · 09-12-2005, 12:34 PM

Dennis,
As soon as I said could they be leaking into one another I realized it's impossible. I took it down to AC brake and had their service manager look at the MC. At first he ask me how old it was, when I said one year he acted surprised and said it looked ten years old. Said he had seen the crystal stuff on remans before, aluminum oxidation and brake fluid getting hot. Felt like I had something leaking, probably in the hoses.

So I have a new MC and new lines to install. Starting tonight and will fully bleed both circuits.

You know, I pullled the metal sheild that sits between the engine and the fender last year and never re-installed (thinking cooling improvements). Could it be that the headers are heating up the fuild in the res and boiling if off there?

overlander63 · 09-12-2005, 07:19 PM

Quote:

Originally Posted by swebster

You know, I pullled the metal shield that sits between the engine and the fender last year and never re-installed (thinking cooling improvements). Could it be that the headers are heating up the fluid in the res and boiling if off there?

DOT3 brake fluid is supposed to have a boiling point of 450 degrees. I would hate to think your master cylinder has gotten hot enough to boil the fluid

.
I think it would be a good idea to replace the shield, if you still have it.

swebster · 09-12-2005, 09:17 PM

Terry,
Thanks. I know I am grasping at straws - it just kills me to not know what went wrong. I replaced the MC and the front lines tonight (just finished). Waiting on the rear hoses to come in. Bought myself one of those new fangled vacuum bleeders to boot so I can replace all of the fuild a little easier.

The hoses did not show any indication of a failure, also did not see any wet spots on the front hardlines. Also did not see anything on the HB or anything else for that matter.

Tomorrow the rears.

urbanextreme · 09-13-2005, 07:22 AM

have you pulled your rear drums? You could have an issue with your rear brakes.

swebster · 09-13-2005, 09:17 AM

urbanextreme,
Yes, well actually, mine are discs in the rear and I replaced them this Spring. I will be back there again tonight replacing the rear hoses and bleeding the breaks. Is there something in particular for me to look out for back there?

urbanextreme · 09-13-2005, 12:16 PM

Just thinking. I have had them leak from the caliper seal and lose fluid that way. Brake fluid is hygroscopic and, once saturated with moisture, can completly evaporate, so you can't quite tell a leak if you lost the fluid some time ago. If you had the calipers replaced last year, once you get the brakes functioning again, have someone press the brakes down with what ever assist your vehicle has, then pay close attention to the piston seals on the calipers and the drop of the pedal.
FYI, fluid will never boil at the master cylinder, it will only boil at the caliper piston under severe continued braking, this is what's called "brake fade". Moisture absorbed into the brake fluid, like the cap off for extended periods or open container that has been sitting on the shelf a long time, is what reduces the boiling point of brake fluid.

ALANSD · 09-13-2005, 04:54 PM

so how often should we change to fluid, and is it ok to not change all of it? I mean pull a lot out thru the master rather than bleed it out at the wheel cylinders...