Brake fluid change

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LC67Vert
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Brake fluid change

Post by LC67Vert »

The brakes on my ’67 Lincoln were redone about 5,000 miles ago including a new brake master cylinder and new brake fluid. This was a few years ago and the brakes still perform well. I am considering changing the brake fluid due to the time that has passed since it was last changed. I am wondering what others are doing as far as brake fluid changes on their old Lincolns. Do you wait until an issue arises to change it, or do you change the fluid based on the amount of time or mileage that has passed? All comments and suggestions are appreciated.
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Re: Brake fluid change

Post by LithiumCobalt »

Jeff, I normally leave stuff alone unless there is trouble, but for as much as these cars sit, a change once in a while probably isn't a bad idea. Last time I replaced my master cylinder, I used a pressure bleeder for an easy fluid exchange. Took longer to set the bleeder up than it did to do the actual procedure. Here was my thread on it: https://www.thelincolnforum.net/phpbb3/ ... t=+bleeder
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Re: Brake fluid change

Post by TonyC »

I agree with Nick on leaving stuff be unless an issue arises, like a leaky cylinder, for instance. DoT-3 brake fluid isn't really something that calls for routine replacement, like motor oil. The last time I did a brake bleed was when I replaced a leaky rear-wheel cylinder, and the brake shoes in the process, early last year. I check the level regularly, and that's about it. Now, if a car sits for several years unused, then yes, it would be a good idea to change the fluid out. But if you use your car even several times a year, and you have no issues, don't fix what doesn't need fixing.

One irritant I know of where '67 brakes are concerned, the differential in the system was woefully inadequately designed. When it goes off-balance, it's all but impossible, in many cases actually impossible, to re-center it and keep it centered. They should have thought about installing return springs in there to keep that ruddy piston centered. That was what they did with differentials in cars from the '70s onward; they should have thought about that in '67. If a breach in the fluid lines occurred, the piston could still shift to the breached side to trigger the light and warn the owner, but would return to its center position when the brakes are released. It could still warn, and finding the leak would be an easy matter for a mechanic. I'd toyed with the idea of trying to install springs inside the shell myself, to achieve that; but the piston is jammed on the inward side, against the side that doesn't have the access nut, and there's no way for me to get it out. I've tried needle-nose pliers, even hydraulic pressure from that side of the brakes with the access nut removed, and it won't budge. Since at least it was designed not to obstruct fluid flow even in an off-center position, I just have learned to live with it. Since Frankenstein does not have a factory-installed warning light for the brakes, I don't have to suffer with a red light that stays perpetually on.

I do have one question about fluid, however; I'm fairly sure it's been addressed before, but it's been a very long time so I'm not 100% sure: Comparison of DoT-3 and DoT-4 fluids. I know there's a difference between the two, but is that difference so great that one cannot mix the two? I know that DoT-3/4 fluids must never be mixed with silicone-based brake fluids. But what about mixing -3 and -4 with each other?

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Re: Brake fluid change

Post by action »

The answer, in my opinion, is it depends -

Brake fluid (DOT 3, 4, & 5.1) is hygroscopic, meaning that fluid absorbs moisture. Moisture in brake fluid over long period of time is an issue. A big issue! This is the reason to "flush" brake fluid. Many maintenance intervals for this service is 5 years.

Here is where I say it depends.
The hydraulic braking system is sealed. UNTIL the operator removes the cap on the master cylinder or a leak occurs. Typically the exposure to the outside air under those conditions is rather short. Newer systems have translucent master cylinder reservoirs so there is less of a need to remove the cap. For a hobby car It may even be a longer duration to have the master cylinder cap removed because the car only sees 1000 to 5000 miles a year.

With that said, I live and drive a number of vehicles in Phoenix, AZ.
The average humidity here is less than 15% for most of the year and 30 to 40 percent during a few months of the year. Humidity is 12% at the moment and average annual rain fall is under 10 inches we will not even come close to that this year. What I am saying is the opportunity in certain locations is different than others. You list your location specifically as the Northeast. That may be more humid.

If I lived in a humid area and use the vehicle more than 5000 miles a year, I would be inclined to flush every 5 years. Where I live, I pray for rain, and won't flush for a decade. Usually by that time, I am replacing a caliper or the master cylinder and the system gets flushed for any of those repairs anyway.

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Re: Brake fluid change

Post by papawayne »

Here in Maine we have high humidity, and where I live, salty air. I took apart a set of brake cylinders a few years back and they were so rusted and pitted that no amount of honing would have helped. Now to be truthful this was not on a Lincoln, but it was on a Ford. Wayne
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Re: Brake fluid change

Post by LC67Vert »

Thanks for the responses. I am also inclined to leave things alone until they require attention. However, brakes are so important on such a heavy car where the emergency brake may not be enough to slow the car quickly should the need arise. I have a 10 year old BMW and the manufacturer recommends brake fluid changes every 2 years, but of course this car has ABS and other sensitive hydro-electric wizardry which may be more sensitive to contaminated brake fluid. I think I will just do a close inspection of the entire system and if any of the hydraulic components need to be replaced I will change the fluid then. Tony posed a good question about mixing DOT-3 and DOT-4. Any thoughts on this?
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Re: Brake fluid change

Post by action »

Phoenix - Yeah, it's hot, however it's a dry heat
2006 Lincoln Navigator Limited 5.4l 3V
1996 Lincoln Mark VIII 2DR Coupe Diamond Anniversary 4.6l DOHC, 4R70W, 3.07
1970 Continental Mark III Triple Black 460 4v, C6, 2.80 (Used for Woodward Dream Cruise or just generally stored in Michigan)
1966 Lincoln Continental 4DR Convertible 462 4v, C6, 3.00
1966 Mercury Park Lane 4DR Breezeway 410 4v, C6, 2.80
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Re: Brake fluid change

Post by tomo »

Phoenix system brake fluid test strips do a good job of detecting copper in the fluid. The more copper in the fluid the more corrosive the fluid is. The kicker on this is that they are expensive (about $19 for 2 strips). If you are handy, it is much cheaper to change the fluid on a regular basis. I don't remember having a problem with centering the balance indicator on my 67, but I sold it in 72.

The electric pen seem to have poor reliability, so I would not invest in them.

IMHO cars that are not used much, tend to accumulate more moisture in the fluid as it does not get as hot as regularly used cars.
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Re: Brake fluid change

Post by TonyC »

I think it's plausible to deduce that Tom didn't have his '67 long enough for that balance differential to cause problems; they likely didn't start to jam up until about 10 to 15 years after they were made. Now, I don't know any surviving '67 that doesn't have that problem...except for those that have been converted with more modern combination valves.

---Tony
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Re: Brake fluid change

Post by Solid »

Changing the fluid every couple years is a good idea even if it has not been opened. The original single and the later dual master cylinders on these cars do not have the best engineered seals for their tops. Moisture is going to get in there. Flushing the system doesn't just remove any absorbed moisture, it also removes any debris that has ended up in the fluid from seals degrading etc. It is cheap insurance relative to replacing wheel cylinders and lines or worse.
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Re: Brake fluid change

Post by frasern »

If you store the car for long periods, I have found pumping the pedal from time to time helps to keep it working. Better to change fluid too soon than too late, but 5000 miles isn't much. I had no problem centering the valve on my 67.
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Re: Brake fluid change

Post by LithiumCobalt »

Using the power bleeder, I had no issue with the valve going off center. There’s enough pressure to move the fluid, but not enough to move the valve off center.
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Re: Brake fluid change

Post by LC67Vert »

frasern wrote:If you store the car for long periods, I have found pumping the pedal from time to time helps to keep it working. Better to change fluid too soon than too late, but 5000 miles isn't much. I had no problem centering the valve on my 67.
I agree 5,000 miles is not much, but what about time intervals? To keep things lubricated and working well I try to drive my Lincoln at least once a week, except in Winter months when sometimes the car sits for several weeks between being driven. On a car that is driven only a few hundred miles a year how long should one go between changing brake fluid? A few years, 5 years, 10 years, 15 years?
Jeff
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Re: Brake fluid change

Post by LC67Vert »

LithiumCobalt wrote:Using the power bleeder, I had no issue with the valve going off center. There’s enough pressure to move the fluid, but not enough to move the valve off center.
Thanks for the info. I am hoping I won't have to deal with a problem with the centering valve.
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Re: Brake fluid change

Post by tomo »

You could buy a couple of sets of the test strips and then check it for a few years to get an idea of the time considerations. I flush my modern cars every 3 years, now that I don't drive them much. My old cars have DOT 5 fluid which does not need flushing as often. I went 20 years on my 40 Mercury and the fluid was still purple with no signs of corrosion in the cylinders.
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