Brake fluid refresh? OT

[91C2wrencher]

On my C2 I flush the brake fluid every 2 years. But on my other cars I never change it. Two questions.

Does it matter on "other cars"?

Does it do any good to suck out the old fluid with a baster from the resivoir and top off with new fluid? As a shortcut?

Ya, I know this post is marginal on P-car content, but you guys are a wealth of knowledge. If I get a couple of quick answers I'll delete the whole thread - presto!

[Eugene at Pelican Parts]

All brake fluids absorb moisture from the air, therefore need to be bled out at suggested intervals. However, the higher the boiling point of the fluid (i.e. ATE Super Blue), the more moisture it absorbs. If you wish to not bleed your Porsche so frequently and it is a street-only car, DOT3 will suffice. Although ideally, hydraulic brakes are closed systems, the fluid will eventually take in some moisture over time, causing boilovers at excessive temperatures.

[Rick Lee]

You have got be kidding me! Call me anal, but I would not go 2 yrs. without changing brake fluid in any car. I've flushed my 993 twice already since May. OK, the second time was just to be extra safe before a DE. Lose your pedal at 130mph and you'll fast become a believer in frequent flushing. Aside from that, getting moisture and goop in the lines contributes to their failure and even hanging calipers. For $44 you can buy a power bleeder and at $12 per can of ATE and maybe an hour of labor, this is about as cheap an insurance policy as you can buy. And geeze - you have a C2. I can't imagine what your clutch slave cylinder will spew out after two yrs. Ask me how I know.

[Jdub]

It matters even more on other cars if they are older and more susceptible to internal seal rot. If they are junkers maybe that is another thing -- you may be driving them into the ground on purpose and, hey, that's not unheard of!

The baster move is a good one if you are going to be bleeding the car. I always pull the old fluid out of the resevoir, clean up the resevoir with nice threadless paper towels, and then put the new fluid in.

Do this for your peace of mind. I'd do the C2 once a year as a minimum. Your car is too nice to NOT do this for it.

John

[Jim Sims]

Brake systems are not closed to the air. The master cylinder reservoir vents to the atmosphere and the fluid therein absorbs moisture. The pads wear and the caliper pistons move outward requiring more fliuid from the reservoir and in the water goes. Cheers, Jim

[sammyg2]

Besides reducing the boiling point of the fluid, the entrained moisture can cause deterioration of the internals in the calipers and master cylinder over time. not only the seals as previously posted but the bores could get corroded.
Changing brake fluid periodically will increase the life of the calipers and the master cylinder.

[Eugene at Pelican Parts]

It's peculiar how the average automobile owner is unaware of his/her vehicle's need for regular brake bleeding service. It is apparently not nearly as marketable as oil changes or radiator flushes since there is usually a quick-lube station within spitting distance of any 'local' Starbucks. Automobile maintenance is a market highly driven by advertisements and coupons. Although it is common to find one for brake pads or shoes, it is a rarity to see brake bleeding offered at all in any Pennysaver or Coupon-Pak. So how is the typical driver supposed to know if Coca-Cola isn't telling them what to drink? The trust is placed within the hands of the average mechanic, trained to think "if it ain't broke...", thus providing them means for a return visit several thousand miles later (and a few more dollars in their pocket). Everybody eats, right?

Ask your friends and family about the fluids in their vehicles. Remind them that they should ALL be changed and advise them of their frequency. Preventive maintenance is more than just frequent oil changes, and ALL drivers should know that.

Oh, and Jim Sims is right (as usual, here on this board). I was a bit 'decaffeinated' earlier.

[VincentVega]

Funny you mention the baster idea. At a nameless dealer that's how they bleed brakes as park of a service. The resevoir comes off the master cylinder, the tech dumps the fluid, attaches the resevoir and fills. 30 second brake bleed. Gotta love flat rate.

In my other cars I usually bleed the brakes when I replace them. Funny how rebuild calipers for my honda are ~$25 each. How much is a 911 caliper rebuild kit?

[91C2wrencher]

Ok, OK! Jeez... Thanks for all the responses. I'm aware of the pitfalls of not flushing the fluid, I've had a "soft pedal" at the track even after a full flush/bleed(that'll get your attention!). But the thing is, I've never given my other cars a second thought, not now, not ever before with any daily driver(non-p-car) I've owned and those systems seemed to operate fine for 5,6 or 7 years. My question was does "topping off the resevoir" w/o bleeding(after all I really don't like spending time wrenching on the Lumina-duh!) a better solution than just leaving the old fluid in? Does Brake fluid "circulate" around or would the newer fluid in the resevior just stay put and not get down to the calipers?

[sammyg2]

Another factor, how long do you intend to keep the car? Lots of folks buy a car every three or 4 years so brake bleeding isn't important to them. If they intend to keep the car for 10 years it starts being very important just like radiator flushes.

As a little side note, two years ago when I bought my SC I spent a couple months taking care of little problems and brake fluid flushing was one of them that I didn't quite get around to yet. I took the car to Willow Springs (SOW) and 15 minutes into the first 20 minute session my pedal went to the floor and I had to throw it sideways to keep from going to a "bad place". Boiled the fluid big time.
Scared the you-know-what out of me but the only damage to the car was brown dirt everywhere. After the brakes cooled down enough to get my pedal back I limped into town and bought a turkey baster, new brake fluid, and some tubing.
Laying down under a car in 100 degree heat saying "pump it up, hold it...." wasn't my idea of fun.
Car was fine for the rest of the sessions after I got clean fluid in there.
mental note to self, next time make sure you get around to it.

[Jim Sims]

Brake fluid doesn't circulate much; recall how small in diameter the ID of the "hard' brake lines are. However, when one installs new full thickness pads and pushes the caliper pistons back, fluid is pushed back to the MC reservoir and if one has been adding fluid or if all the pistons are pushed back at once to make clearance for pad installation the reservoir can overflow; is the overflow hose connected? The time to exchange the most fluid using the "baster method" is after installing new brake pads. I do not recommend this except as a measure to remove as much of the old fluid as possible (to avoid pushing it all the way through the system to the caliper bleed screws) before adding new fluid for a proper fluid exchange/bleed. To truly get the new, clean brake fluid to the calipers the system has to be bled. Cheers, Jim

[Rick Lee]

And when no turkey baster is available, you can do the siphon method, as demonstrated here by Green912 on my 993 at a tech session. Don't worry - he was sucking on a second piece of tubing inserted way above the fluid level in the catch can.

[91C2wrencher]

Well, thanks again for the input. Looks like we've pretty much covered this idea/concept/system/short cut/lazy a$$/get off my butt/and/change it out/on my other cars.

[David]

I think changing brake fluid every year in an anti-lock brake equipped car is a must. Even if you don't bleed the high pressure pump, at least change the fluid so the next time the anti-lock kicks in it will get fresh fluid. Calipers may only be a few bucks but the pump is probably over a thousand.

[911pcars]

I know a lot of folks use a pressure bleeder for changing/bleeding brake fluid. At its best, its a quick and easy method of bleeding the brakes.

However, I don't feel comfortable with pressurized brake fluid near painted surfaces. Someone on this forum recently shared that the (pressurized) bleeder hose came adrift from the reservoir which managed to spray the Porsche paint with a gush of expensive paint remover. I hope he saved it in time with a timely spray of water. His fault or not, it's still a possibility. Those who live life on the edge may disregard my wimpish warnings of impending paint doom.

I vote for the turkey baster for these reasons:
1) Most folks already have one in the kitchen. Single-use kitchen utensils are passe (ask me how I use a can opener on my 911).
2) Another place I wouldn't want brake fluid (even DOT4) is in my mouth (see prior post).

You need a 3' length of nylon hose from the local hardware store. Buy the one that fits snugly over the bleeder screw. After taking out most, but not all of the fluid from the reservoir (you don't want to introduce air in the system do you?), fill w/fresh fluid, then loosen the bleeder screw with the tube attached. Stick the end of the tube into that empty water bottle you were thinking of using to suck fluid out of the reservoir. Gravity (there's a word pressure-bleeding proponents disdain), will push the old fluid out. When the fluid looks clear (or less murky), close the bleeder valve. Repeat three more times and you're done with a minimum loss of sometimes expensive fluid.

You're welcome,
Sherwood Lee
http://members.rennlist.org/911pcars

[l8tapex]

Regarding "other" cars last weekend I bled the brakes on my 98 Volvo wagon. I started out using my suction bleeder but the calipers don't hold enough fluid. I was sucking air before the vacuum ran out on each pass. After a few frustrating attempts I reverted to the 2 person method of pumping the brake pedal and it worked like a charm.

[emcon5]

Originally posted by Chris Martin
Funny how rebuild calipers for my honda are ~$25 each. How much is a 911 caliper rebuild kit?

For a SC/Carrera, about $12 per corner.

Tom

[Randy Webb]

Yes, completely replace the fluid every 2 years in every car you own.

There will be diffusive mixing of the old & new fluid if you replace that, but complete mixing could take eons (OK, well, maybe just epochs) and the effect of the new fluid will be reduced. So do it.

[Bill Verburg]

Replace every 2 yrs at a minimum in all cars, humid climates more often, tracked cars more often.

I like the low pressure bleeders best but the Mityvac suction bleeder also does a good job as long as the seal at the nipple is solid(this can be a problem with older hose sections).

[l8tapex]

I like the Mityvac suction bleeder also. I've had it for over a year and I can't say a bad thing about it. It comes in a nice carrying case with a bunch of nipples for different size caliper bleed valves. One downside is that it was a bit pricy. I paid about $50 bucks.