leaking brake hold off valve problem

[pink aar]

Is anyone using DOT 5 brake fluid in their car? I put DOT 5 in my car and I've had 2 hold off valves leak. Inline tube said, it may be because of DOT 5 fluid???? Has anyone had a leaking hold valve from Inline tube? They admit there was a problem with the valve in the pass, but they couldn't be 100% positive the DOT 5 was the problem now. Any help here would be grateful.  THANKS

[anlauto]

I've been using Dot 5 in all my restorations for years.

[pink aar]

You haven't had any problems Alan??

[anlauto]

I've had leaks before, loose lines, bad valves etc....but never once considered that Dot 5 might be the problem.

With a hydraulic clutch system it says right in the instructions NOT to use Dot 5 because of the seals or something like that   

[Rich G.]

White Post Restoration just sleeved and rebuilt my M/C and its guaranteed for life and void if you use dot 5.

[anlauto]

White Post Restoration just sleeved and rebuilt my M/C and its guaranteed for life and void if you use dot 5.

Curious, what was their reasoning ?

[Shane Kelley]

 Those repop valves have a issue with the O ring seal. Everyone I have taken apart has ended up having a small cut in the ring. New O ring is the simple fix. Other than that issue I have had no problem running DOT 5 in all the cars I have built including my own.

[Rich G.]

I just called White Post Restoration and ask why no dot 5 and he said the rubber they use is not compatible with dot5 and they have had lots of problems when using it. He also said if it's so good why aren't car manufacturers using it! Got a point there I guess.

[Shane Kelley]

Just a FYI. Not saying it's right or wrong. Article I found on the subject.

Can DOT 5 Brake Fluid Be Used Instead of DOT 3 or 4?

Always refer to vehicle owner's manual for what the manufacturer recommends or warns against. As a rule, vehicles equipped with anti-lock brakes (ABS) should not use DOT 5 brake fluid.

DOT 5 brake fluid is silicone based. DOT 3 (standard) and DOT 4 (heavy-duty) are glycol-based. It can be distinguished from conventional brake fluids by its purple color (which comes from a dye).

Silicone does not absorb moisture. DOT 5 brake fluid does not become contaminated with moisture over time as conventional DOT 3 and 4 brake fluids do. Silicone is also chemically inert, nontoxic and won't damage paint like conventional brake fluid. It also has a higher boiling point.

Because of this, it is often marketed as a premium "lifetime" brake fluid. It is often used to preserve brake systems in antique vehicles and those that sit for long periods of time between use.

DOT 5 silicone brake fluid is also very expensive (costing four to five times as much as ordinary brake fluid), and it won't mix with glyco- based brake fluid (creating concern over sludging if all old fluid isn't removed when a system is refilled with silicone).

Silicone also has slightly different physical properties and compressibility, making it unsuitable for ABS systems calibrated to work with DOT 3 or 4 brake fluid.

[GoodysGotaCuda]

DOT5 in my car and clutch. No leaking problems, but none of it is factory either.

I won't use DOT 3/4 unless I have to. But you do need to start with fresh seals to go to or from DOT 5


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