DOT3 or DOT5?

[Moparman]

So im about to bleed the brakes, silicone warning sticker is still on master cylinder but i found a bottle of dot3 in the truck. Proceeded with a water test and the bottom stayed murky and darker foam stuff on top. Im not a genius but im sure someone mixed them. Will i be ok with bleeding it all out with fresh dot5? Brakes are ok, gets spongy but no leaks. Any help will be appretiated!

 

[offroadrunner]

I suppose it depends how much was in there, and how long it was there. My experience - when I converted my '73 Polara (stock - DOT3) and my deuce (which the previous owner switched to straight DOT3) to straight DOT5 was that any "rubber" parts (in the master, slaves, hoses, air-pack) that I tried to re-use - failed within 6 months. It seems that DOT3 causes the soft-parts to swell (slightly) and soften (a little) - and when you go to DOT5 they shrink back or harden and leak (or hoses de-laminate on the inside). Also - I think that DOT5 seems to "feel" a little spongier than the same system with DOT3; not a lot, but it seemed noticeable.
If you had much DOT3 in there, you probably shouldn't push your luck.

 

[Moparman]

Here is what the water test looks like, I guess since there is already dot 3 in there with no leaks, I will go ahead and use dot 3.

 

[MarcusOReallyus]

I wouldn't. I'd flush it thoroughly and rebuild everything. Then refill with DOT3.

Brakes are no place for shortcuts.

 

[Bob H]

All my Dodges have been switched to DOT3,
Deuces are still DOT5

 

[emmado22]

Make sure your insurance is all paid up if your going to NOT replace all the rubber pieces...

 

[hndrsonj]

Wheel cylinder and Master Cylinder rebuild kits aren't too bad in price. The airpack kits can be reasonable if you get them at a show or watch ebay. I'd stick with Dot 5.

 

[Bob H]

Wheel cylinder and Master Cylinder rebuild kits aren't too bad in price. The airpack kits can be reasonable if you get them at a show or watch ebay. I'd stick with Dot 5.

It's a 77 Dodge pickup, no air pack, rebuilt wheel & master cylinders are generally cheaper than the rebuild kits at the autoparts store.

 

[Bill W]

FYI
Heres how the military handled the switch over from dot 3 to dot 5. http://test.steelsoldiers.com/upload/M35/TB43-0002-87.pdf

 

[emr]

Bleed it out and run it.