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Driving on the interstate, locally at about 80 mph in my 95Q I suddenly begin to lose power and try to shift down but still very little power. Foot to the brake to get off at the next exit and the brakes are stone cold locked. Of and much nasty grounching noise, smell and ultimately smoke accompanying this. I get the car towed to my mechanic who called this morning to report all four brake disks glazed; brake material on the disks and calipers a mess. Clearly something occurred to have this happen to all four brakes. His thought is either the ABS unit or the master cylinder. I bought the car a year ago and other than new brake lines and fluid, no other brake work. 57K miles.

He suggested replacing the brake components and disconnecting the ABS unit when done to see if I still have any problems. If so, a new master cylinder would be in order. If not, hook up the ABS unit and drive to see if that is a problem. Anyone else have thoughts?

Thanks in advance.
 

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I would recommend hooking up the Fiat Lancia Tester with module MA7A to check stored errors and the functioning of the solenoid valves. Also a complete changeover of the brake fluid.
 

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Usually a master cylinder is the cause of this; but usually its only two wheels (diagonal front and back) that lock up. ABS can only relieve / pulse brake line pressure, it can not add brake line pressure to any meaningful degree as far as I am aware {{EDIT -- I somewhat retract this last bit, I am not sure how much pressure the pump can add back -but it can add some I know. I guess if the pump turned on, and left all the valves in 'control' mode (that would be a two point failure I think) what you describe could happen, as said before a whacky ABS computer could single-fault that I suppose...????}}.

I think you are due for a new master. That is what I would replace first; even with only 57K miles (yes I know its low) the master is 20 years old already--

Be aware that many places will tell you you have to replace master and booster all in one. See if you can find someone around your area to rebuild the master and then you don't have to buy an expensive whole assembly (tolerances between master and booster are very tight and hard to measure, you want about 0.3-0.5mm slop between booster and master ). If you rebuild your old one (seals and maybe a slight polish) you will not change the clearances
 

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The 94/95 24v 164 model takes different master cylinder than 91-93 12v models. It also has a different brake booster. They two units originally only sold as an assembly. I think maybe Jason and Difatta Bros can sell you just the master cylinder.

http://www.alfissimo.com/index.php?productID=1462

or call www.difatta.com

They both should have brake rotors and pads, too.

I take it you have a brake problem and the engine runs fine?
 

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Don't buy just the master unless you can do the metrology to set the clearance. Too little and the brakes will bind up when the assembly gets hotter, too much and there is excess pedal travel before brakes engage. Suggest you rebuild your current master and re-install it with the shims it has AS-IS.
 

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Also, to be sure, do use the best high temperature brake fluid you can buy such as the ultra good ATE 200. It's superior, more heat resistant, to the ordinary autoparts store high temp fluids.

I had a problem with the brakes on the 91S coming on in hot stop and go driving. After changing to the ATE Blue (the ATE 200 is the newer non-blue version, as mandated by the Feds), that problem went away for good.

At first the mechanic thought it was the master cylinder going bad (and I'm not saying that a bad master is not your problem), but after having the problem raise it's head again after changing the master cylinder, We went to the ATE high temp Blue/200, and it solved the problem, the fluid not boiling anymore, the brakes not coming on by themselves since.
 

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One of the sad things about the Marelli modules are their poor documentation. I peeped inside of the MA7A—at the parts of the code in ascii—there you will get a glimpse of what the tester does for the ABS diagnostic. (following is a screenshot)
 

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Discussion Starter #9
Thanks for the suggestions. Steve: you are correct, the engine if fine. Brakes are toast. Pinnino: If I can't get the mechanic to confirm it is the master cylinder, I will see if your offer of use of the tester is the next step. And Goats: I don't know if i can get it rebuilt in a timely fashion. If I have to "buy" I will try to get both the cylinder and the brake booster.

Thanks for the timely help!
 

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Locked brakes has happened to me too. On the road, 50 miles from home.:001_unsure:

Sat and thought about it for a while, then out with the tool kit I always carry. Just barely cracked the first brake line banjo I could get to, out squirted a little fluid, so must have been under pressure. Brakes now free, I drove carefully home. Changed the MC - and all is well. Just another day with my Alfa.

Merry Christmas all.
 
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