What type of brake fluid should I use in my Citroën 2CV ?

This question recently was sent in and here is my answer:

1. If you have a pre 1980s Citroën 2CV (that is a Citroën 2CV with four wheel drum brakes), then you want to use a good quality DOT 3 or DOT 4 brake fluid . My own personal choice is a DOT 4 product made by Castrol called Castrol LMA . (the LMA stands for low moisture absorbing ). As we all know, this is a good quality for brake fluid to have since it is by nature hygroscopic, or has a tendency to absorb moisture.
   Regardless, the other bit of info I can’t stress enough is to completely drain and flush out the system at least every 2 years in your Citroën 2CV . More problems and troubles with brakes seem to be caused by neglecting to do this fairly simple procedure, and moisture builds up in the system and corrosion occurs.
2. OK, second answer to the question: If you have a Citroën 2CV that is later then this date or has disc brakes on the front to be more accurate, then you want to be using LHM fluid . Yes, the same green stuff that you put in the hydraulic suspension cars of the same period.
   Here again you want to practice my advice of changing the fluid at least every two years. Changing the fluid is such an inexpensive form of maintenance, next to rebuilding or changing out brake parts. The more I find, as these Citroëns get older and enter collector status, people have a tendency to use them less and less, and this is where periodic maintenance becomes even more important.

So take care of those Citroën 2CVs because they just don’t make them anymore!

Later,

Denis

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What do you do if your Citroen has a contaminated Hydraulic System?

I know that I have harped on this subject for several articles now, but it is more of a problem than you might think. I found when I worked on Citroens , the cars either caught fire and burned or were abandoned because the hydraulic system had become contaminated and the owner found out that it was going to be mighty expensive to repair the car.

Well, the shop manuals and the dealer bulletins would tell you to replace some of the major rubber components. Then, if the car was a brake fluid car you were supposed to flush the lines out with first alcohol , then (I love this) gasoline , then alcohol again. If the car was LHM you were to use: gasoline , then alcohol . The systems were then to have compressed air blown through them to dry things out.

Now here is my advice…

Most cars, unless you catch it right away, are far too gone with rubber deterioration to merely have a few things replaced and then blow things down with air. What you have to realize is, just like a dirty gas tank , you either deal with it completely or walk away from the car.

You have to weigh what the car is really worth to you and the market, because what I am going to tell you is the cheapest way to deal with this problem.

Find another Citroën of the same vintage with the same hydraulic items on it. What I mean here is, if it has a Citromatic or hydraulic assisted transmission , you want to find another car with that same option.

Now this Citroen should be one with all the proper hydraulic parts and systems intact, but find one that is either an accident casualty, or a car with a rusted out frame. If you find one that is both then you really did well, because that means you can probably buy this Citorën quite cheap and in this situation, that is the name of the game.

Next you want to put your Citroën next to it, remove all the body panels, put it up on jack stands or a lift and start removing all the hydraulic components , and I mean everything . This includes all rubber hoses and return lines , even the hydraulic tank . Once this is done you want to shoot carb cleaner and then compressed air through all the steel lines that are still on the car.

Repeat this process twice.

Now that is done, sit that rusted out car that you purchased with the same components on it next to your keeper and start removing the parts from it and putting them on yours. This will probably take you or your mechanic a good 40 hours worth of labor time, so be sure to weigh this into the final cost of things when you figure whether your car is worth performing this task on or just walking away from.

Be a realist and face up to the fact that unless your Citroën is a fine example with a fresh motor, a nice interior, sweet frame, and a good looking paint job, you might be better off trying to find another nice example of your car without a contaminated hydraulic system .

This problem will not just go away on it’s own.

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Do you think your Citroën has contaminated hydraulic fluid ?

My little video yesterday showed you a simple test to do if the LHM system has a little brake fluid in it. Now I will tell you some of the tell tale signs to look out for when the system might be contaminated.

This may seem silly for a system that is marked properly on the hydraulic reservoir for what type of fluid it should take. But, many of these cars change hands numerous times. (just watch eBay for a few months and you will probably see the same car come up again and again with a different seller each time) There are just people out there who might toss something into the system before they realize what it takes.

The hydraulic system of the Citroen is composed of quite a few rubber components. In the early days, with the Citroën15/6 H and the early D Model, a rubber called EPDM was used when LHS2 , a form of brake fluid , was used.

Later, when they devised a rubber that would stand up to mineral based oil, they started to use Buna . A few other types have come along over the years as improvements in rubber manufacturing have been devised.

One thing I have to say here about EPDM compared to Buna in standing up to its respective fluids, is that EPDM stands up far better to brake fluid in the long run than Buna does to LHM . I say this because, when I take apart an old brake fluid sphere to rebuild the rubber diaphragm , it is always in good shape and still holding gas , sometimes almost 50 years on in many cases. (That is if it always had the proper fluid in it.)

The other thing is the EPDM was much less susceptible to molecular diffusion , or the loss of gas then the Buna .

The Buna on the other hand (if it is an original diaphragm ) has always turned to GOOP . The newer rubbers they have now hold up must better I must say, but that original Buna was not good in the long run.

I guess the point I am trying to make here, is that rubber for hydraulic use is designed to hold up to the specific fluid that runs through it. Pollute this in anyway, (and I mean it just takes only 1 to 2 percent of the wrong fluid in the system) and the rubber parts will start to deteriorate very quickly.

The way the system is set up, the parts effected first are those ones with the biggest surface area and the most fluid traveling across them. In the case of the Citroen , this is the diaphragms in the spheres . So, one of the first signs you will probably have is a ride that starts to deteriorate. Next, as the diaphragms blow out and gas from the spheres is injected into the hydraulic system, you will start to get air in the brake system as the gas is circulated through the system.

As the ride deteriorates and the brakes start to get air in them, the fluid level goes down in the system, as the entire sphere needs to be filled up with fluid at this point. You will also notice the hydraulic pump start to cycle with greater frequency.

The steering at this point no longer has any power assist!

Now hopefully the owner realizes what is happening before this situation happens, but if he doesn’t, then he is in for an expensive bill even if he does a lot of the work himself.

Next, I will cover what would be the most cost effective way to handle the above condition.

Later,

Denis

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