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Topic ClosedMaster Cylinder: call roto-rooter!

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Turbo301 View Drop Down
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Direct Link To This Post Topic: Master Cylinder: call roto-rooter!
    Posted: 18-April-2010 at 10:44AM

Today I found the time to tear into my master cylinder... well, sort of. I at least got it off the car!

Alas, what I found was not very encouraging: upon draining off the fluid in the tank, I found that about 25% of the volume was taken up by this hideous brown sludge. Yum... There is quite a bit of rust on the underside of the lid and between the booster and cylinder. Any bets that that brown sludge is rust?
 
 
 
 
Also, the shaft that sticks into it, as part of the booster, has a fair amount of corrosion on it. The seal looks good, although it is slightly lifted at one side (see picture), so I am really hoping I don't need to do anything to it. Anyone agree/disagree with that? I also pulled on that shaft and it felt like it dislodged from its rear bearing within the booster; it re-seated okay, though. Is that okay? I don't honestly know what the inside of a booster looks like, or what can move, how. I can turn the shaft by hand, and it rotates somewhat stiffly and "cogs" slightly; is this the normal feeling for a booster?
 
In its current state, is it safe to start the car and monitor the state of the booster's shaft when the brakes/vacuum are applied, and if so, what performance should I see at its shaft?
 
 
Also, at the local Canadian Tire, all the fluid they have is "DOT 3" or higher. Is fully-synthetic Dot 3 okay for these systems? There's no mention of a "DOT" rating in the owner's manual.
 
Once my new cylinder is in, I'll bleed the system as best I can to try and get whatever rust junk may have entered the system, out. Once it runs clear, I figure I should be okay, but is there a threat of damage to the rear cylinders and other parts from this nasty stuff?
 
Thanks to all for your help so far!
 
1977 Cougar XR7
1980 turbo Trans Am
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Direct Link To This Post Posted: 18-April-2010 at 2:51PM
Use dot 3 or dot 4.  I would not use dot 5 or any synthetic unless you are planning on completely bleeding the whole system and making sure everything in it is synthetic
79 LTD II 408/TKO/3.7's

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Direct Link To This Post Posted: 18-April-2010 at 6:10PM
Originally posted by Turbo301 Turbo301 wrote:

Today I found the time to tear into my master cylinder... well, sort of. I at least got it off the car!

Alas, what I found was not very encouraging: upon draining off the fluid in the tank, I found that about 25% of the volume was taken up by this hideous brown sludge. Yum... There is quite a bit of rust on the underside of the lid and between the booster and cylinder. Any bets that that brown sludge is rust?
 

Probably. 
 
Originally posted by Turbo301 Turbo301 wrote:

Also, the shaft that sticks into it, as part of the booster, has a fair amount of corrosion on it. The seal looks good, although it is slightly lifted at one side (see picture), so I am really hoping I don't need to do anything to it. Anyone agree/disagree with that? I also pulled on that shaft and it felt like it dislodged from its rear bearing within the booster; it re-seated okay, though. Is that okay? I don't honestly know what the inside of a booster looks like, or what can move, how. I can turn the shaft by hand, and it rotates somewhat stiffly and "cogs" slightly; is this the normal feeling for a booster?

I'd say it's fine. The shaft can be pulled out and reiniserted. That seal will not seal tight without the master installed. 

Originally posted by Turbo301 Turbo301 wrote:

 
In its current state, is it safe to start the car and monitor the state of the booster's shaft when the brakes/vacuum are applied, and if so, what performance should I see at its shaft?


There's no way to check it like that. You need the brakes fully installed and bled. Either they work or they don't. If the pedal wasn't hard like a brick with the engine running, but was fairly hard with the engine OFF, and there were no weird squeaks or hisses coming from the booster itself while the car was running, you should be fine. 
 
 
Originally posted by Turbo301 Turbo301 wrote:

Also, at the local Canadian Tire, all the fluid they have is "DOT 3" or higher. Is fully-synthetic Dot 3 okay for these systems? There's no mention of a "DOT" rating in the owner's manual.
 
Once my new cylinder is in, I'll bleed the system as best I can to try and get whatever rust junk may have entered the system, out. Once it runs clear, I figure I should be okay, but is there a threat of damage to the rear cylinders and other parts from this nasty stuff?


You should be alright. At this point, I think the damage is done, if any, anyway.. I would use a CLEAN EMPTY 20 oz clear bottle of soda with a rubber hose over the bleeder screw. Have a friend watch the bottle as you pump the pedal with the bleeder open, and you will visually see the clear fluid come out. 


[/QUOTE]
Paul
77 XR7 460/C6/3.00:1 *SOLD*
78 XR7 523/C6/3.5:1
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Direct Link To This Post Posted: 18-April-2010 at 11:33PM
Thanks for the reply, guys. It makes me feel better knowing that my booster is probably okay.
 
And yes, I was planning on bleeding the system until I see only clear fluid come out; I don't care if it takes 5L of the stuff :).
 
I read that the copper brazing from the brake lines gets picked up by older/broken-down fluid and can deposit; I haven't dug around in the muck in the MC, but it's possible that it could at least partially be dissolved copper. Yummy...
 
Since the body and most of the  structure of this car are so solid, it makes me wonder how this thing got so much grossness into its braking system. It also surprises me that it would pass a safety this way, but then again, from my experience, most mechanics don't do a very thorough inspection when you get a safety done.
 
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Direct Link To This Post Posted: 19-April-2010 at 1:21AM
Originally posted by Turbo301 Turbo301 wrote:

Thanks for the reply, guys. It makes me feel better knowing that my booster is probably okay.
 
And yes, I was planning on bleeding the system until I see only clear fluid come out; I don't care if it takes 5L of the stuff :).
 
I read that the copper brazing from the brake lines gets picked up by older/broken-down fluid and can deposit; I haven't dug around in the muck in the MC, but it's possible that it could at least partially be dissolved copper. Yummy...


I've never heard of that, or seen that in some cars with 40 year old SEALED brake systems.. It's usually rust. 
 
Originally posted by Turbo301 Turbo301 wrote:

Since the body and most of the  structure of this car are so solid, it makes me wonder how this thing got so much grossness into its braking system. It also surprises me that it would pass a safety this way, but then again, from my experience, most mechanics don't do a very thorough inspection when you get a safety done.

Again, it's just water in the air, condensation, over 30 years..

Safety? Not sure how Canada is, but MA does a 'safety'. Depending on the tech you get, he will either just pass your car outright, or if he's feeling pretty malevolent, he'll pump your pedal HARD, hoping to break a brake line or to get the light to come on. :). 
 

Paul
77 XR7 460/C6/3.00:1 *SOLD*
78 XR7 523/C6/3.5:1
79 F100 460/TKO500/3.25:1
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Direct Link To This Post Posted: 19-April-2010 at 1:28AM
Usually they just take a brief look and pass the car, especially if you take it to your mechanic and tell him to, um, "overlook" some things (like a missing catalytic converter :). Even when you tell them to look for any potential weak areas, they don't often put a lot of effort into it.
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Direct Link To This Post Posted: 19-April-2010 at 12:08PM
As a fully licensed mechanic in the Province of Ontario I have a BIG problem with anybody asking or telling a mechanic to "um overlook" some things. If this guy did such a thing he should immediately have his licence revoked and charged with attempted murder! He is not doing you or anyone else who use the roads a favor by acting this way.
In my years I have had people try everything even bribery with me to pass a car that shouldn't be on the road. I have even had the unpleasant task of reporting another mechanic to the authorities when I had inspected a car for a second opinion.
Guys like these are what give good honest mechanics a bad name. Canadian Tire is also one of the worst places to take your car to.

Use DOT 3 fluid. Look for the FORD spec DOT 3 as it has a higher temp rating. Stay away from synthetic unless you have a million $$ paint job you are worried about. To use synthetic every part of the brake system with have to be completely rebuilt by replacing any part that has rubber in it (master, calipers, wheel cylinders, proportioning valves, etc) because if you don't there will be a chemical reaction and it will destroy the internals and leave you with no brakes at all.
If you can get your hands on a pressure bleeder you can borrow, reverse flush the system with the master off to ensure all contamination is removed. Do not try to reuse that master. For what they are worth rebuilt, just get a rebuilt one for the car. Cheap insurance and peace of mind.
Ian Glyn-Jones
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Direct Link To This Post Posted: 19-April-2010 at 12:39PM
There are lots of shady mechanics out there, unfortunately; the guy who certified my Cougar is likely one of them! It was the dealer who sold it to me, his shop certified it. He had new flex hoses put on, but I'm guessing he didn't bleed the brakes or he would have seen this gunk and done something about it. I would have taken it to my mechanic to check out but it was too far a drive, and I work too late in the day.
 
And yes, I've heard horror stories about Canadian Tire; I'd never go there.
 
I read that synthetic DOT 3 is fully compatible with other synthetic and "regular" fluid, just not silicone brake fluid; is this incorrect? Do you know what kind of elastomer the seals are made out of? I deal with chemical compatibility of elastomers on a daily basis (I work in aerospace engineering), so I can probably determine if certain chemicals will hurt them.
 
And yes, a rebuilt master is only $40, so it's so not worth trying to clean and re-use my rusty, gross and scored master. The bore is pretty messed-up.
 
That pressure bleeding idea is a good one! Not sure I'll have that luxury, unfortunately.
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Direct Link To This Post Posted: 19-April-2010 at 12:44PM
I don't have the wheels off to check; can someone tell me what size of hose I'll need for bleeding? I'm heading to the parts store tomorrow and I'd like to get some hose while I'm there.
 
 
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Direct Link To This Post Posted: 19-April-2010 at 2:32PM
Originally posted by iangj iangj wrote:


Use DOT 3 fluid. Look for the FORD spec DOT 3 as it has a higher temp rating.
Wouldn't DOT 4 be just as good to use as the DOT 3 Ford as it has higher temp ratings and is compatible
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Direct Link To This Post Posted: 19-April-2010 at 6:12PM
$40? did you check Rockauto? I think I got mine for $8. 
Paul
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Direct Link To This Post Posted: 19-April-2010 at 11:18PM
I'd never heard of Rockauto before; they do have quite a variety and seem to be a pretty good deal! Shipping on such a heavy item up to Canada would be a killer, though; I think that'd make it cost more than the one I got in a hurry.
 
But thank you for pointing out that company for any future parts needs!
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