gooey brake fluid/melty looking lid gasket

I picked up a super clean 1990 chevy 1500 short bed 2wd pickup for super cheap because it has no brakes.

i pulled the master cylinder lid and the lid gasket is very soft and looks like it is melting and is very deformed.

the brake fluid is disgusting. not brown and dirty but has white clouds in it, is thick, and the white clouds are gooey.

i would assume this means there has been something added to the brake system that is not brake fluid - like power steering fluid or some other clear thicker liquid that most certainly has no place in a braking system. there are no leaks in the system but it just will not build pressure. all steel lines are clean and beautiful because truck is from texas. am i correct in this assumption?

assuming i am correct i pretty much want to replace everything that is not the steel lines in the system, and flush them out very well prior to hooking up the new components?

the truck came with brand new loaded calipers with all hardware. i have a good master cylinder from another truck i parted, and i would eliminate the ABS pump anyway because it is rear only and i do not like it. this leaves wheel cylinders and 3 rubber hoses as the only things to purchase.

what to flush steel lines with? brake cleaner and let them sit a day before hooking stuff up?

i think i'm barking up the right tree but have never dealt with a contaminated brake system before.

Yep, sounds like somone dumped the wrong stuff in the MC. You'll need to replace everything rubber. That means either rebuilding or replacing the master cylinder, calipers (even though they look new, if there's oil or P/S fluid in them the seals are toast), wheel cylinders and the proportioning valve.

As far as flushing the steel lines, when this has happened at shops I have worked at the best thing to do is use brake cleaner in a spray bomb, use the little tube and blow this through the lines till it comes out clear. Brake cleaner will evaporate on its own pretty quickly but deep inside those steel lines it's nearly impossible to guarantee all of it will evaporate so immediately put a blow gun on the line and blast for at least 15 seconds, the air should come out clear when it's all out. Once that's done, no reason you can't start reassembling immediately.

Exactly what he said, have had to do this on a couple occasions.

I'll add that if the wrong fluid was added recently, the seals in the calipers are probably okay. But, you don't know how long it's been, and if you already have new calipers, why not? Wheel cylinders are cheap to replace, too.

You MAY have to replace the prop/combo valve as well. Maybe.

yeah the brand new calipers are on the front seat in boxes, not installed, so that is a big plus.

i believe i have a master and prop valve on the shelf.

being such a popular truck i am sure the hoses are super cheap as are the wheel cylinders. i'm ready to replace everything but the hard lines, brakes are not a cut corners item. plus i got such a smoking deal on the truck it is worth it.

just and added thing to check, when you take off the Master Cyl if it has already degraded to the point it leaked into the the brake booster you might need to swap it too as the mystery sludge might well destroy the rubber diapgham in the booster.

got it. have a booster too on the shelf just in case.

just ordered all new GM hoses and wheel cyls from amazon for less than chinese parts store parts.

Would alcohol be a good flush for the steel brake lines? then blow out w/ compressed air. Seems I heard that somewhere.

i agree with everything except removing the RABS, but hey, i'm just a brake system engineer with 20 years experience including performance development of RABS at the vehicle level.

1. suck out as much fluid as you can from the MC reservoir
2. flush system with denatured alcohol
3. flush system with clean brake fluid
4. swap MC
5. flush system with clean brake fluid
6. ?
7. Profit

in my experience with high mile 88-92 gm trucks the rear ABS is ususally broken and setting the BRAKE light, so the pump is one more potentially damaged thing to get out of the system. i personally prefer no ABS because i get in situations where it tries to kill me, like when i am going downhill on a bumpy road coming to a light pulling a trailer and the ABS activates from the bumps and tries to let me roll right through the intersection while it helps me stop on the slick road it thinks i am driving on.

add in this truck will see no to very little winter driving and it makes sense to me on a molecular level to remove the potentially damaged abs pump from the DNA of my truck. i do, however, respect your experience and opinion on the matter. i do plan to keep this one for a very long time so i am thinking purely of my own preference here and not the next owner, because chances are it might stick with me forever. i've been hunting a 5 speed shorty forever and when the opportunity to pick one up from texas pops up in northeast ohio, you just do it.

I've heard of using alcohol too, but never tried it. About RABS: my '94 Rodeo had Isuzu's version and it was pretty transparent. I think I only had it go off 2 or 3 times and that was on dirt roads, just had a rattly pedal, truck stopped fine.

They used alcohol to flush the lines on my '48 IH KB1 back in 1976, when the brakes were bleed they ran a little more brake fluid through the lines and cylinders to flush all the alcohol out of the system. So the alcohol flush has been around for a long time. I still have the truck, patted it on the hood as I walked by it today.

All good advice so far, but I will just add in my own personal point- whenever I hear anyone use the term "brake oil" I correct them. Oil implies a person could use any old oil they had laying around. Power steering oil seems to be the most popular...

ok it's fixed and stops great.

i removed all the components from the system that were not steel lines.

blew out the lines with air. blew out the lines with brake cleaner. blew out the lines with air again.

installed new hoses, wheel cylinders, calipers, master, prop valve, tossed the abs pump. bled with my motive pressure bleeder. have brakes now.

one of the pristine factory steel lines got replaced because it got hurt on the inner fender edge rubbing against it for what looks to be a long time, and it cracked there when i moved it. other than that and finding a leaking rear axle shaft seal there were no surprises. that only added 20 minutes and 15 dollars to the job so no harm there.

thanks guys, now time to fix the smooshed front end.

pages wrote: ok it's fixed and stops great. .. . .. . now time to fix the smashed front end.

How much of a screaming deal was this again? Did they pay you to take it?

it just needs a bumper up front really, but i am turning it from a simple bumper swap into way more than it needs to be. taking off the work truck sealed beam headlight grill and putting on a whole 96 gmc composite headlamp front end. and adding power windows and locks. and new style mirrors. and dropping it. and etc...

pics?

patgizz wrote: it just needs a bumper up front really, but i am turning it from a simple bumper swap into way more than it needs to be. taking off the work truck sealed beam headlight grill and putting on a whole 96 gmc composite headlamp front end. and adding power windows and locks. and new style mirrors. and dropping it. and etc...

FYI, the sealed beam headlights are VASTLY better than the composites.

fasted58 wrote: Would alcohol be a good flush for the steel brake lines? then blow out w/ compressed air. Seems I heard that somewhere.

I got one in that had been filled with DOT 5 silicone fluid. I won't use that stuff (whole other topic) so drained the system by pulling the bleeders and soft lines at the calipers. Put everything back together and filled it with denatured alcohol then opened the bleeders to let it gravity bleed. After it was running clear I went through 2 quarts doing a full pressure bleed (using the alcohol) then opened it up again to drain. Put it back together once more and flushed 2 quarts of DOT 4 through it on a pressure bleed. Big PIA to do but worked well.

Jeff

In reply to JKleiner: dot 5 and dot 3-4 are not interchangeable, or compatible with each other. I'm glad that yours survived, but usually when the 2 are mixed the whole system (except hard lines) needs to be rebuilt.

I run into this problem a lot with industrial vehicles.

old_ wrote:

patgizz wrote: it just needs a bumper up front really, but i am turning it from a simple bumper swap into way more than it needs to be. taking off the work truck sealed beam headlight grill and putting on a whole 96 gmc composite headlamp front end. and adding power windows and locks. and new style mirrors. and dropping it. and etc...

FYI, the sealed beam headlights are VASTLY better than the composites.

this is true but the grilles are vastly better looking with the composites. i've had both as i have been driving 88-98 trucks since i've had a license. i have some silverstar bulbs anyway.