Hey guy's..is it ..ok..to use mineral spirits to flush out the old..DOT 3 ..before puttin in ..DOT 5 silicone?

 

nooo, use brake fluid
you aware there is a DOT 5.1 also?

 

really???...says rite on the DOT 5 bottle to...flush out the ..3...and dot 3 n 5 do not mix???...so what ya mean use brake fluid??

 

....hello...can you..explain that answer??..are you telling me to..mix..the 5 with the 3 to use as a..flush??

 

Jack Mac you CANNOT mix the two they are incompatible and will form a gelatinous mess in your system. I just went through this so..

As far as how to purge your system of its DOT 3 there are various arguments on how extensive you must be. Some feel you need to take the entire system apart to clean it thoroughly, or even more start with brand new components. Some feel that it is not worth it and the benefits of Dot 5 are not there. Sorry All I know is what I have read.

I assume the reference to DOT 5.1 above is that you can use Dot 4 or Dot 5.1, which are superior to Dot 3 but not have to go through the hassles of flushing your system in that they are compatible with Dot 3.

So here you go. Asking about various Dot fluids is like asking about what color makes a Vette better. Good luck!!!!!! Ike

 

OP, what's wrong with using DOT 3 or 4? I once considered 5 but not needed for just street cruising. I put DOT 4 in mine.

 

When I bought my '79 it had already been converted to silicone fluid. I have maintained it with silicone fluid ever since (25 years). Not sure I would have made the conversion if it were up to me, but it works well enough. The PO told me he flushed the system with alcohol when he did the conversion.

 

hmm..rubbing alcohol..?...thats mostly water...ok...good to know

 

JackMac my limited research, I found that the only advantage to Dot 5 was if you store the vehicle for long terms it would prevent corrosion. But for dialy use it seemed to have no advantages and a few disadvantages that seem to outweigh them. Ike

 

...well that's gonna be the biggest problem with this..restore..sitting in the garage...disadvantages??..like what?..thanx...

 

JackMac sorry I am a little confused, are you restoring a Vette that has been sitting for many years or are you planning on "hibernating" a Vette for many years. It appears, from what I read,that Dot 5 was created for the military that stores vehicles for years unused. It avoided the nasty corrosion that Dot 3 is known for. Other then the anti corrosion factor (Which is quite a big deal), Dot 5 has no other major advantages.

So if you are waking up a sleepy Vette Dot 4 and 5.1 can be used to replace Dot 3 without the concern of it being non compatible with Dot 3, if you are thinking of upgrading your fluids.

Certainly not a bad idea to flush out the system anyway to get ride of that old fluid and corrosion none the less.

Brake fluid is a hot topic on car forums. Everyone has their own opinion!

Ike

 

I should have said alcohol, read this link
https://www.corvetteforum.com/forums...ake-fluid.html

 

NO........I believe that "denatured alcohol" is what you need, but I think you should double check this. Have you considered contacting the vendor of the brake fluid you're intending to use?

 

isopropyl alcohol is used

 

Flush out the old DOT 3 with new Dot 3, you don't need DOT 5.

 

yeah Ike..this is a ..restore job ..the car sat for 30 + years...i need to flush out the ..ugly stuff that is in there ..preferably with something other than DOT 3 fluid...and i usually go with the ..5..when i overhaul..and yes this car will be ..sitting for ..long periods..between drive's...thats why I asked about using..mineral spirits to do the ..flush n clean...thanx..

 

I would not use rubbing alcohol. As you say it is mostly water. I don't think you want that in your braking system. I'm not sure it would matter what kind of alcohol you use as long as it is pure alcohol. Methyl or isopropyl should be fine. Denatured ethanol is just ethyl alcohol to which something has been added to make it undrinkable. That would work too.

 

Lots of bad conflicting info out there. I will add my 2cents....you can flush with what you like but solvents are not reccomended. Any solvent left in the system will vaporize quite easily and cause a loss of braking function. Even 1 year old DOT 3 will have absorbed moisture but new DOT3 is dry. DOT5 does not absorb moisture. Fresh DOT3 is good for a flush and cheap. The dirt is the biggest enemy of the system followed closely by moisture. After the system is flushed, you must replace any and all rubber pieces in the system before conversion to DOT5. The old rubber pieces have absorbed the old DOT3 along with the moisture it brings with it. The old (moisture laden) DOT3 can leach back out of the old rubber and allow corrosion in the new system, even with new DOT 5 fluid in there. That is the reason you must replace ALL the OLD rubber pieces when converting to DOT 5 fluid. After the flush and rubber replacement you can fill/bleed with DOT5 and you will be fine. All the fresh DOT3 used for flushing left in the lines will come out when the DOT5 is run through the lines during bleeding. The bubbles will stop and the color will change when its gone.

Motive Pressure Bleeder is your friend as long as you add a c-clamp and a block of wood on top of the master cylinder while bleeding.

This information comes from the Stainless Steel Brakes Corporation P/N 8001 - 65-82 Corvette Brakes Service Manual. I have done this to my old cars that sit for long periods of time and it has worked great.

 

Is there some special reason for flushing with alcohol? Or mineral spirits? Are they solvents for brake fluid? Is it easy to purge from the system afterward? Is any residual harmless if mixed with the new fluid? Harmless to brake components? Why not kerosene? Degreaser? Acetone? Just curious.

 

Any other liquid or solvent remaining in the system after a flush can vaporize at high temps during braking application causing a vapor bubble, making the system not functional. You heat up the brakes from hard running and they stop working.

Fresh brake fluid has a high boiling point to prevent this. Old DOT3 will have absorbed moisture over time and that will greatly reduce the boiling point of the fluid. Moisture allows fluid to boil easier at a lower temps. Moisture absorption also allows internal rusting. These are reasons why you must drain/fill common brake fluid as part of regular maintenance. DOT3 and DOT4 are hygroscopic so they absorb moisture from the air.

DOT5 does not absorb moisture so it does not need to be changed at regular intervals. DOT5 also does not disolve paint like DOT3 or DOT4 does.