Was thinking of flushing the DOT 5 fluid and putting non-silicone back?

[TWINRAY]

What do you think? I've been running silicone for over 20 yrs. Now I thought it was great because it doesn't absorb water but the water just puddles up. I have to do caliper seals anyway and if I flush every couple of years, I'll be fine - right? And save a couple of bucks too.

 

[JohnZ]

Ideally, you need to disassemble the whole system and flush/clean it with alcohol if you want to change from one fluid type to the other, as the two fluids aren't compatible or miscible. I'd just stick with what you have now and give it a good flush/bleed so the whole system has fresh fluid in it.

 

[TWINRAY]

Ideally, you need to disassemble the whole system and flush/clean it with alcohol if you want to change from one fluid type to the other, as the two fluids aren't compatible or miscible. I'd just stick with what you have now and give it a good flush/bleed so the whole system has fresh fluid in it.

Hi John,
The calipers will be resealed and will go in dry. If, prior to me connecting the lines, if I run 2 qts of Dot 3 or 4 thru, will that be "good enough" of a flush? I'm tired of paying $15-20/qt for the silicone.

 

[JohnZ]

I wouldn't recommend that approach - I'd blow out the lines and flex hoses with alcohol and compressed air to get all the DOT5 out (or just replace the flex hoses if they're over ten years old - they're cheap), bench-bleed the master cylinder with alcohol to get all the DOT5 fluid out, then do it with DOT 3/4, lube the caliper piston seals with DOT3/4 when you go through them, then fill/bleed the system with DOT3/4.

 

[TWINRAY]

I wouldn't recommend that approach - I'd blow out the lines and flex hoses with alcohol and compressed air to get all the DOT5 out (or just replace the flex hoses if they're over ten years old - they're cheap), bench-bleed the master cylinder with alcohol to get all the DOT5 fluid out, then do it with DOT 3/4, lube the caliper piston seals with DOT3/4 when you go through them, then fill/bleed the system with DOT3/4.

That is my intention when I get my MOTIVE bleeder in tomorrow. I was neglective in my bleeding of these lines over the past 16 yrs and the "gunk" around the seals was pretty unbelievable.

 

[TWINRAY]

Whose idea was this? The 2 big fittings going into the junction block right under the master don't want to budge. Hopefully after soaking in PB Blaster for a day, they will move today. I'd thought the smaller ones under the junction block would be the troublesome ones. Oh well, after working on these for 30 odd years, nothing really surprises me.