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Brake Line Leak with DOT 5

Started by autoluke, May 07, 2009, 07:02:20 AM

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autoluke

After trying numerous sealers, including Teflon tape, I have been unable to stop DOT 5 fluid from seeping around the flared line connections.    The problem  is confined to the nut-to-flare attachment, and not to the threaded connection.   

Any suggestions  ?

Phil
Phil Lukens

The Tassie Devil(le)

G'day Phil,

Sounds like you have a scored or broken flare.

I would recommend having the Flare remade, and not use Teflon Tape at all.

Using tape will not allow the fitting to fully seat, and you run the risk of getting some of it into the system.

Bruce. >:D
'72 Eldorado Convertible (LHD)
'70 Ranchero Squire (RHD)
'74 Chris Craft Gull Wing (SH)
'02 VX Series II Holden Commodore SS Sedan
(Past President Modified Chapter)

Past Cars of significance - to me
1935 Ford 3 Window Coupe
1936 Ford 5 Window Coupe
1937 Chevrolet Sports Coupe
1955 Chevrolet Convertible
1959 Ford Fairlane Ranch Wagon
1960 Cadillac CDV
1972 Cadillac Eldorado Coupe

mario

gentlemen:
also teflon tape is so slippery will allow the overtightening of the joint and possibly splitting the flare (causing a leak.)
ciao,
mario

Don Boshara #594

Is that a double flare, it should be.
1940 Sixty Special
1966 Mustang Cpe

Chris Conklin

And teflon tape, like pipe dope, is used as a lubricant and not a sealant.
Chris Conklin

paul

why not use dot 3 ? ive never heard of this. Is thisi a silicone brake fluid? If you go aroubd and bleed out your systen completely every 2 years the dot 3 fluid will work just fine for decades. You have to also exersize the car by driving it and keeping the pistons from setting up. Are you making your own flares? I neveer heard of putting any teflon tape on brake parts or connections. Its as taboo as using a compression fitting to repair a line. Could your brake block have a crack or be stripped. Are alll of them leaking. i would not trust that even if you got them sealed. they could start leaking at any time. Use whats proven. what was made for the car. good luck

35-709

Another topic  discussed at length (with some disagreements) here in the past.  DOT 5 Silicone brake fluid has plenty of advantages that (to ME) far outweigh any disadvantages and it is especially good in cars that are not used very often.  Most feel that one must start out with a system that has not seen DOT 3 fluid, in other words a freshly rebuilt system with new/rebuilt components.  Any vehicles that I own and keep, or plan to keep, for awhile get converted to silicone brake fluid.  Harley Davidson motorcycles come from the factory with DOT 5 silicone brake fluid and have for several years.  I personally would not do a brake system restoration and not use silicone fluid.
Why Phil's system is leaking I do not know --- fittings not tight enough, cracked flares (I've bought 'em new from NAPA cracked), not double flared, etc.  A friend had trouble getting his system on a '57 T'Bird to stop leaking, he had used all new stainless lines and found that really tight was necessary to stop the seepage he was getting.

You might try putting "DOT 5" or "Silicone Brake Fluid" in the Search feature of this site and see what comes up. 

I have never heard of using any sealers of any kind on a brake system either and would be hesitant to do so. 
1935 Cadillac Sedan resto-mod "Big Red"
1973 Cadillac Caribou - Sold - but still in the family
1950 Jaguar Mark V Saloon resto-mod - Sold
1942 Cadillac 6269 - Sold
1968 Pontiac Bonneville Convertible - Sold
1950 Packard 2dr. Club Sedan
1935 Glenn Pray - Auburn Boattail Speedster, Gen. 2

paul

I have never heard of leaking lines from silicone brake fluid. although i dont use it myself the purpose of using it was percisely that it did not trap moisture and the pucks in the wheel cylinders would not get sticky. It was to be used in a new brake system meaning all components were new or newly rebuilt. i restored a guys 55 nash wagon and he requested i use it so i did. it was just fine and he drove the car many miles and years for that matter trouble free. I service my own vehicles so i bleed out my system every couple years and add fresh fluid , regular dot 3 and put thosands of miles on my cars so it works just fine for me. I agree there must be some other reason your lines are leaking and i to would not use any sealants or tapes or even a compression fitting on a brake system that has to be reliable on a public road. good luck

Glen

Quote from: Geoff Newcombe #4719 on May 11, 2009, 09:55:43 AM
A friend had trouble getting his system on a '57 T'Bird to stop leaking, he had used all new stainless lines and found that really tight was necessary to stop the seepage he was getting.
 

I can believe that.  When the flare nut is tightened down the flare of the tubing is mashed down on the cone of the fitting to form the seal.  Stainless is less malleable than the plain steel lines. 

Glen
Glen Houlton CLC #727 
CLCMRC benefactor #104