Yup, I don't mean to cause you to over-react. The flushing the lines I mentioned is only after the entire system has been badly contaminated. Yours hasn't. The steel lines are not made of cast iron, so they're not porous and won't absorb the contamination. It's sufficient to blow in Brake Parts Cleaner from a spray can, then blow that out with compressed air. Carburetor Cleaner is designed to evaporate very quickly. Brake Parts Cleaner hangs around much longer to give you time to scrub and wash parts, so it needs the extra air to disperse it.
Every year I did a demonstration where I had two beakers, each with about an inch of fresh, clean brake fluid. I dropped a brand new wheel cylinder lip seal into each one, then I added one drop of power steering fluid or engine oil into one of them. Set them aside for one week, then pulled those seals out, washed them off, and passed them around. The contaminated one had grown by roughly ten percent, and felt soft and slimy.
I have four stories to share to add context to this problem. The first one was in a class at a Sears Auto Center training center. In the 1970s and 80s, a common tool was a "bleeder ball" that held up to about four gallons of brake fluid. It was pressurized with compressed air, then attached to the brake fluid reservoir to pressure-bleed the system. When it needed to be refilled, the hole was so small that we used a long plastic funnel, and poured the new fluid from five-gallon cans. We heard about one fellow who knew about the contamination concern, so when he used a funnel they used for engine oil, he thoroughly wiped it out first with a rag. It was the residue left behind that contaminated all that new brake fluid, and then got into the brake systems. Sears had to replace all the rubber parts on over a dozen cars. Once we heard that, we had a special, dedicated funnel used just for brake fluid.
Second story, also at Sears, a down-and-out fellow came in with a Ford station wagon he had just bought for $100.00. The right rear brake was locking up, but it was the only one that was applying. Found the seller had filled the reservoir with automatic transmission fluid. Made the brakes work really nice, ... For a few days, then the problems started. Don't know what the final outcome was on that one. We didn't go any further other than to explain what had happened.
Third one happened to a K-car when I was working at a very nice Chrysler dealership in the '90s. Fellow just got back from a cross-country trip. He claimed that at one gas stop, the attendant checked the fluids and asked if he should top off the brake fluid, (something we never do except during regular brake system services). "That must be where he put in power steering fluid by mistake". I never pressed him, and of course he couldn't remember where that happened or the name of the place, but I think he did it himself and just didn't want to admit it. How did he know it was power steering fluid? I don't remember if we repaired that one or if he went on his way.
The fourth one was on a '59 Edsel I bought from an estate auction. Was a big, heavy, fun car to drive, but after a few weeks, I drove it 55 miles to a car show swap meet. Left home with a full tank of gas. Ran out on the return trip, less than half way back home. Coasted into a gas station but missed the pumps by about ten feet. Couldn't push the car by hand, but luckily my folks were following me. Used their Caravan to push me to the pump. Once I got home and hit the granite driveway, the right front brake locked up and the tire skidded all the way to the garage. Found that reservoir was also filled with automatic transmission fluid. I was able to buy the wheel cylinder lip seals individually, and I found the seals for the single master cylinder. I flushed the steel lines, but I neglected to replace the rubber flex hoses. That should have been part of the repair, but the car was old enough that parts we hard to find. I sold the car to a well-off friend of a friend who parked it behind his business. It sat there unmoved for years, so he probably gave up on it. According to my training, those rubber hoses, which are porous, held some of that contamination which leached back out to recontaminate the new fluid.
There's one more place where contamination often occurred. That was on older cars with tapered front wheel bearings that we had to manually "repack" with grease, by hand. Rebuilding calipers and wheel cylinders was a common practice since it was much more expensive back then to replace those assemblies. Regardless, once the services were completed, the last step was to refill the brake fluid and bleed the system. Typically the rubber bladder seal under the reservoir cap had pulled out over time as the brake fluid traveled out, down to the wheels. That had to be poked back in, and we did that with a fingertip. We just wiped our hands on a rag after repacking the bearings, then with that residue on our fingers, poking the rubber seal back put that contamination on it. Today it's common practice for specialists to wash their hands with soap and water before handling any of those rubber parts to avoid getting fingerprint grease on them.
On one hand, we worry about a little residue that's going to contaminate the system, and on the other hand, we find systems completely filled with the petroleum product, and it still takes a few days to show up. Since the grease residue on fingertips rarely resulted in a complaint or objectionable symptoms, I'm pretty sure your penetrating oil is not going to cause a problem. The reason I presented this wondrous story is, in part, for the benefit of others who are researching this topic. Most competent do-it-yourselfers aren't aware of this, and once told of it, many don't believe it. It's easier to be aware of it and work to avoid problems than it is to fix them later.
Thursday, December 26th, 2024 AT 1:19 PM
