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09-11-2003, 12:00 AM
Hey guys,
Help me with a problem. I am leaking brake fluid (dot 3 paint remover) from my master cylinder reservoir cap no matter how tight I screw it down ( or loose ). Every thing in the hydraulics is new. I have to remove it all to repaint ( bummer ) and want to solve the problem before I reinstall. Someone suggested I may have air in the line, hence causing hyper-pressure in the reservoir and forcing fluid out the cap seal.
Too, when reinstalling the slave reservoir, I bought a "racing type" braided hose from the slave cylinder to the piping, thinking the nylon original style hose is a weak point. The instructions that came with it said "not for street use!" Something about improper installation possibilities and "shorting out". Whaaa? Shorting out what? I always thought that the nylon hose was a bad idea but maybe I am wrong and should stick with original equipment stuff. Any ideas?

Tired-of-repainting-in-Louisiana
Bill

(Oh yeah, my car is a cherry [green actually] 1973 TR6)

XK4
09-11-2003, 01:19 AM
IMO it does sound like the system has not been bled enough to remove all of the air from the line or cylinders. Also the fluid shouldn't be filled all the way to the top of the reservoir. It needs space to flow when the fluid gets hot (from hard braking).
My guess with your "shorting" is that the hose has a braided stainless cover. These things eat thru wiring insulation like a hungry wolf and being stainless if it does eat thru some wiring it will be a direct short complete with sparks, smoke etc.
Just make sure no wiring is close to it and it will be fine.
Jim images/icons/smile.gif

Larry Kronemeyer
09-11-2003, 01:40 AM
Brake lines and hoses stating not for street use are not DOT certified. The unions and consistency of the materials are not age tolerant or road dirt tolerable, most are used for racing and show.
Larry

Darwin
09-11-2003, 02:22 AM
Get ahold of a Mityvac and use it to clear your lines. Also check that you are getting fluid to all 4 wheeels with pressure, sounds like a restriction someplace in the circuit. I have also been told that you should use DOT 4 brake fluid or DOT 5 silicone as the DOT 3 will rot the natural rubber seals in our LBC's. Noticed a lot of rubber "goo" in the piston bore on my spitfire when I rebuilt them this summer and it was caused by the DOT 3 I had been using.

Jon12
09-11-2003, 04:01 PM
Do not use dot 3. NO DOT 3. I made that mistake when I first got my sptifire and now a rear wheel cylinder is leaking and my clutch slave cylinder needs to be re-build. So my next project is rebuild all the rubbers in the hydraulic system.

Use castrol LMA, dot 4 or dot 5. Don't mix dot 5 with any thing else though.

Dave Russell
09-11-2003, 04:47 PM
<blockquote><font size="1" face="Verdana, Arial">quote:</font><hr>Originally posted by Jon12:
Do not use dot 3. NO DOT 3. I made that mistake when I first got my sptifire and now a rear wheel cylinder is leaking and my clutch slave cylinder needs to be re-build. So my next project is rebuild all the rubbers in the hydraulic system.
Use castrol LMA, dot 4 or dot 5. Don't mix dot 5 with any thing else though.<hr></blockquote>

Jon,
I don't agree. There is very little difference between DOT 3, & DOT 4.
See this link;
https://www.team.net/html_arc/tvr/200108/msg00027.html

I do agree with using LMA. Quoted from another source;
Castrol brake fluid, GT LMA is a DOT 3- DOT 4 with a glycol ether ester base which is considered to be synthetic in origin, although it is not advertised as such. Castrol GT LMA, which exhibits low moisture activity and exceeds the
most severe performance and safety requirements, is the fluid of choice. For completely reliable brake operation, maintain the required brake system service schedule and use Castrol GT LMA Brake Fluid. The "scoop" is.... Lucas Girling is the brake manufacturer, and Castrol is "Girling Approved".
D

09-11-2003, 07:29 PM
Dave,
I concur on the use of Castrol LMA DOT 3. It is the only proper fluid to use in Girling systems. Silicon fluids will give a "mushy" feel to the braking. I will re-bleed everything, after repainting. Might go with a oil-rig type epoxy coating beneath the hydraulics to prevent the cursed "curled paint syndrome". My car is so modified that I am not worried about sticking to original everthing. Whenever I do modify it is to "improve".
Thanks for the tips, guys.

Bill