Nasty brake fluid

[HelluvaEngineer]

I'm slowly going through the list of regular maintenance on my first m1009. I've had issues with the brake boost being somewhat intermittent. Works great one second and then little to nothing. I checked the brake fluid and it looks like it's been badly neglected. There was literally some goupy mess in the master cylinder and obvious signs of mixing with water.

So I sucked out what I could in the master cylinder and then tried to clear the lines with my Mitivac. Interestingly I was getting very little out of the disc brakes and even less fluid out of the drums. I had to resort to putting a catch can on there and bleeding manually at the brake pedal.

Has anyone else had issues with bleeding these brakes using a vacuum pump, or is the system likely so gummed up everything needs to be inspected? I'd prefer to avoid rebuilding everything, but for example I guess replacement pistons for the drums would be fairly affordable. Any thoughts? Thanks.

 

[eme411]

you do understand that these vehicles use silicone Dot 5 brake fluid, I would suggest that you flush your entire system and see where you end up , you could have anything or everything in there,

 

[Drock]

you do understand that these vehicles use silicone Dot 5 brake fluid, I would suggest that you flush your entire system and see where you end up , you could have anything or everything in there,

Agreed, the "goop" might be a mix of the wrong brake fluids. As for bleeding, I switch ALL my vehicles over to (Russell speed bleeders). They're a check valve design, which I found actually forces air out by keeping slight back pressure when the bleeder is open. Kind of like when you putt your thumb over a garden hose. Also I don't have to ask for help to bleed the breaks, which means one less argument with the wife.

 

[Tinstar]

Agreed, the "goop" might be a mix of the wrong brake fluids. As for bleeding, I switch ALL my vehicles over to (Russell speed bleeders). They're a check valve design, which I found actually forces air out by keeping slight back pressure when the bleeder is open. Kind of like when you putt your thumb over a garden hose. Also I don't have to ask for help to bleed the breaks, which means one less argument with the wife.

What Russell part number did you use?
They do not list a K30 on their website. Just a K10/20

 

[Drock]

What Russell part number did you use?
They do not list a K30 on their website. Just a K10/20

Front pair (10mmX1.5) - (#639580)......... Rear pair (8mmX1.25X24mm) - (#639520)... The only precaution with using these is when your done bleeding them. You'll need to spray a little lube into the bleeder & make sure to use the little rubber plug that comes with them. Otherwise the check valve inside can get rusty and stick next time you need to bleed them.

 

[Tinstar]

I assumed it would be same part number(s) for the K30, but wanted to be sure before ordering.
They are.
Good tip about the lube after use.

Thanks

 

[MarcusOReallyus]

Agreed, the "goop" might be a mix of the wrong brake fluids.

I'd bet money that it is. That system needs a complete flush. That's a good time to evaluate whether or not you want to keep it synthetic, or follow the research that led the military to give up on that stuff and go back to conventional brake fluid.


Either way, you really need to flush it thoroughly and put one or the other in it.

 

[HelluvaEngineer]

you do understand that these vehicles use silicone Dot 5 brake fluid, I would suggest that you flush your entire system and see where you end up , you could have anything or everything in there,

No. If I read that I forgot it. I'd rather convert it over to dot 3. It's not a race car. When y'all say complete bleed do you mean empty the master cylinder? Because that's gonna be a pain to get the air out of. Or can a gradual bleed refilling it with conventional work?

I'm gonna get the bleeder screws. Same wife issue. Thanks.

Sent from my VIVO XL using Tapatalk

 

[doghead]

Should say right on the master cylinder cap, DOT5.

Yes, you need to empty the system, them blow it out, then flush it completely, then fill and bleed it.

 

[MarcusOReallyus]

Or can a gradual bleed refilling it with conventional work?

No.

Really, NO!

Mixing the two will cause your system to fail eventually.


Since you forgot it was DOT5, you probably added 3 at some point, and now you have only two choices: Live with a flaky brake system that might fail completely at any time, or do like doghead said. Drain completely. Blow it out. Flush it out. Refill.

You cannot mix the two!

I think there's a thread around here on how to flush the system properly. You need to use the correct solvent to flush it.


Yeah, it's a pain in the butt. That's the way it is. There are no shortcuts here.

 

[HelluvaEngineer]

I've only had it a few months. I'm pretty sure it had already been mixed together based on what I saw. I'll look for info on flushing with the solvent and also look at the cap.

 

[HelluvaEngineer]

Did a search. For solvents I see denatured alcohol but I think that's more for removing DOT 3/4. Other sites mention using anything that is mineral spirits based...so I'm thinking straight mineral spirits??? Will that trash seals and other components?