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1995 SEDAN DEVILLE-4.9 & 1978 SEDAN DEVILLE-425
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1,673 Posts
Discussion Starter #1
Seems to be a slow leak in my `78 Deville brake master cylinder.
Look to be the original one.
Had brakes checked--no leaks. No brake light warnings yet.
In the master cylinder there are 2 separate bays that hold the brake fluid--the rear bay nearest
the firewall is the one leaking---have to add brake fluid to it every month or so.
I`ve been looking at this close for 3 weeks--sprayed down the area clean with cleaner
and it seems to be leaking from the rear of the cylinder--right where the clip that holds
the cover on inserts into rear cylinder body.
Put in new cover gasket and still leaks--but "not" from gasket area.
Do these brake master cylinders have any internal seals that could leak?
Thanks for any info.
 

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84 Coupe w/500
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5,665 Posts
If it's leaking from the hold down pivet, I'd think the metal is corroding. Don't think there is a gasket there.
 

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1995 SEDAN DEVILLE-4.9 & 1978 SEDAN DEVILLE-425
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1,673 Posts
Discussion Starter #3
If it's leaking from the hold down pivet, I'd think the metal is corroding. Don't think there is a gasket there.
Probably metal corroding,as you say.
Looks to be leaking from hold down rear "pivot".
If it`s original, and it looks to be, probably time for a new one. Held up for 37 years apparently.
The nuts that attach the master cylinder to the big round vacuum booster look to be almost fused to it.
I don`t have knowledge of replacing brake master cylinder, so I`ll have to take it to my mechanic.
Brakes are important and I don`t have a clue on how to bleed them right myself.
 

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1979 Coupe deVille, 1995 Sedan DeVille (sold)
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1,846 Posts
Yes, they do have internal seals that can fail and leak. However, if it was internal, you would not lose fluid - you would lose brake pressure.
 

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1995 SEDAN DEVILLE-4.9 & 1978 SEDAN DEVILLE-425
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1,673 Posts
Discussion Starter #6
I had a brand new one installed today.
Looks nice and shiny under the hood.
Got some peace of mind--for now anyway.
 

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1990 Brougham, 1990 Brougham d'elgance 1979 Coupe
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1,196 Posts
I took a can of cast Iron engine spray paint and sprayed it into the paint can cap and took a 1" foam brush and painted my master cylinder, looks real nice.


Hope the booster is still in good cosmetic shape.
 

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1995 SEDAN DEVILLE-4.9 & 1978 SEDAN DEVILLE-425
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1,673 Posts
Discussion Starter #8
I took a can of cast Iron engine spray paint and sprayed it into the paint can cap and took a 1" foam brush and painted my master cylinder, looks real nice.


Hope the booster is still in good cosmetic shape.
The booster looks it`s age of 37 years. Still works great though!
 

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1990 Brougham, 1990 Brougham d'elgance 1979 Coupe
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1,196 Posts
If its gold anadoized theres not many easy options, eastwood has a spray kit, but I doubt its all that great from what ive read.

If your not worried about it, your stopping now. Black spray paint hides a lot.

Ill bet your car is pretty awesome NOW!
 

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1995 SEDAN DEVILLE-4.9 & 1978 SEDAN DEVILLE-425
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1,673 Posts
Discussion Starter #10 (Edited)
If its gold anadoized theres not many easy options, eastwood has a spray kit, but I doubt its all that great from what ive read.

If your not worried about it, your stopping now. Black spray paint hides a lot.

Ill bet your car is pretty awesome NOW!
Pretty awesome!
My bank account is feeling the "big pinch" though with all the work done on both my Deville`s lately.
I set aside the cash for the recent complete repainting/bodywork on my `78 Deville and new tires on my`95---both look so great
and well worth it---but was`nt planning on new radiator and idler pulley & belt tensioner for my `95. New alternator,belt,replacing cruise and wiper switches/blades,
brake master cylinder on my `78---all in a short period of time.
On the positive side of it all---just glad I was able to find all the parts necessary to keep both running---and I was
able to do some of the work myself.
 
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