have a Lancia Fulvia 1.3 from 1974. I bought it 2003. It was in good condition. Had been used by a swedish lady living i Switzerland using it driving to golf.
When I bought it I changed the break fluid to a syntetisk one advised by friends knowing much more about cars?
About 15 years later the problems began. The breaks began to stick, lock up.
During the 15 years I have renovated the break caliper on all four wheels. I have also renovated the main break cylinder and when I did that I found that the cylinder was full of something blue and grainy. I decided to buy a new break cylinder. I bought it from a company in Berlin. I installed it on the car but could not bleed the system. I tried to bleed the system myself and I had a garage in Tingsryd where I live to bleed it. But neither I or the garage could build up any pressure in the system. I have spoken with the company i Berlin. Their answer is ”noone has complained befor”. I have disassambled the main cylinder, but can’t find anything wrong.
Now I am out of idéers and hope that you can help me. Could the break limitor has anything to do with the problem? Shall I disassamble the whole break system, change all gaskets, fill it with Dot 4 break fluid?
Breaks
Re: Breaks
Do not change more than one thing at once. If you do, you will never know what the real problem was. The brakes worked well for 15 years so it is something of recent change.
I would persist with the DOT5 synthetic. It lasted for 15 years so that cannot be your problem. Returning to DOT 4 or 3 will increase the risk of water in the brakes leading to additional corrosion in the brake calipers.
Now the issues with DOT 5 are that sometimes the brake pedal can feel a little more "spongy" than for the glycol based brake fluids. Also whilst synthetic is not hygroscopic you can under extreme situations end up with water migrating to the lowest point of the brake system because the silicone will float on top of the water. That is, the brake calipers can end up being full of water and therefore prone to corrosion. But bleeding at the calipers every once in a while will tell you if there is a problem.
Now the thing you need to ask your German supplier of the brake master cylinder is whether the o rings and rubber components are compatible with silicone based brake fluid. Some rubbers can be affected by silicone more than for the glycol based fluids and can lead to problems with the operation of the brake components.
Secondly when you said you found blue and grainy materials in the cylinders this could be contamination of the DOT 5 with glycol based brake fluid. There are some new brake fluids called DOT 5.1 which are GLYCOL based and not silicone. The DOT 5 and DOT 5.1 is confusing for some people thinking they are the same thing.
Is it possible that someone at the garage, or even yourself has accidentally contaminated the silicone brake fluid with either DOT 3, 4 or 5.1?
The other way to help determine if your master cylinder is at fault is to "bench bleed" it. What you can do (in the car or removed on the bench) is to provide some hoses from the master cylinder outlet lines to return back to the master cylinder fluid reservoir. When you pump the cylinder, the fluid will return back to the reservoir and you can pump as long as you like because you do not waste any fluid. By doing this you will very quickly see if there is any air build up in the master cylinder of if the pumping is not efficient. Once you bleed out all the air then you can reconnect the pipes to the brakes and most of the air from the system will be gone.
IF you don't get out ALL the air from the master cylinder or from the air lines you cannot get pressure up. But given you took it to a garage, I would think they would know how to do this anyway.
Lastly, check the length of the pushrod from the brake pedal to the master cylinder. They HAVE TO BE identical. If the length of the throw is not the same as the old one then the brake pistons will not push far enough to build up pressure. It is not uncommon to find that the end of the master cylinder may be slightly different and the rod does not fit correctly.
I would persist with the DOT5 synthetic. It lasted for 15 years so that cannot be your problem. Returning to DOT 4 or 3 will increase the risk of water in the brakes leading to additional corrosion in the brake calipers.
Now the issues with DOT 5 are that sometimes the brake pedal can feel a little more "spongy" than for the glycol based brake fluids. Also whilst synthetic is not hygroscopic you can under extreme situations end up with water migrating to the lowest point of the brake system because the silicone will float on top of the water. That is, the brake calipers can end up being full of water and therefore prone to corrosion. But bleeding at the calipers every once in a while will tell you if there is a problem.
Now the thing you need to ask your German supplier of the brake master cylinder is whether the o rings and rubber components are compatible with silicone based brake fluid. Some rubbers can be affected by silicone more than for the glycol based fluids and can lead to problems with the operation of the brake components.
Secondly when you said you found blue and grainy materials in the cylinders this could be contamination of the DOT 5 with glycol based brake fluid. There are some new brake fluids called DOT 5.1 which are GLYCOL based and not silicone. The DOT 5 and DOT 5.1 is confusing for some people thinking they are the same thing.
Is it possible that someone at the garage, or even yourself has accidentally contaminated the silicone brake fluid with either DOT 3, 4 or 5.1?
The other way to help determine if your master cylinder is at fault is to "bench bleed" it. What you can do (in the car or removed on the bench) is to provide some hoses from the master cylinder outlet lines to return back to the master cylinder fluid reservoir. When you pump the cylinder, the fluid will return back to the reservoir and you can pump as long as you like because you do not waste any fluid. By doing this you will very quickly see if there is any air build up in the master cylinder of if the pumping is not efficient. Once you bleed out all the air then you can reconnect the pipes to the brakes and most of the air from the system will be gone.
IF you don't get out ALL the air from the master cylinder or from the air lines you cannot get pressure up. But given you took it to a garage, I would think they would know how to do this anyway.
Lastly, check the length of the pushrod from the brake pedal to the master cylinder. They HAVE TO BE identical. If the length of the throw is not the same as the old one then the brake pistons will not push far enough to build up pressure. It is not uncommon to find that the end of the master cylinder may be slightly different and the rod does not fit correctly.
Re: Breaks
And one further question.
When you originally changed to DOT 5, did you replace ALL off the rubber components in the system and flush out all traces of the glycol based brake fluid? That is, brake master cylinder and disc calipers? It is recommended that ALL rubbers are replaced when doing so to prevent any cross contamination in the system.
When you originally changed to DOT 5, did you replace ALL off the rubber components in the system and flush out all traces of the glycol based brake fluid? That is, brake master cylinder and disc calipers? It is recommended that ALL rubbers are replaced when doing so to prevent any cross contamination in the system.
Re: Breaks
I second everything that viiking wrote. The switch to silicon based DOT 5 brake fluid is not an easy one, as it must not ever be contaminated with any leftover glycol based DOT 3, 4 or 5.1 brake fluid.
I only have two thoughts to add:
- your brake hoses may be deteriorated and/or clogged with the same grainy stuff, prohibiting flow to the calipers
- I've heard of rare cases, maybe once or twice in many years, where the interior seals of brand new aftermarket master cylinders were mounted in the wrong way, and the cylinder did not work properly. So it's not impossible, but also not very likely. I don't know who supplied them.
I only have two thoughts to add:
- your brake hoses may be deteriorated and/or clogged with the same grainy stuff, prohibiting flow to the calipers
- I've heard of rare cases, maybe once or twice in many years, where the interior seals of brand new aftermarket master cylinders were mounted in the wrong way, and the cylinder did not work properly. So it's not impossible, but also not very likely. I don't know who supplied them.
Re: Breaks
Bernt has raised a good point about the hoses. Yes check these as well.
The other problem with hoses is that even though they look perfectly fine on the outside, they can collapse internally so that little or no fluid can flow through them.
You end up with a situation identical to your own heart where the arteries can block. That is, atherosclerosis.
If the hoses are 15 years old then they could already be damaged.
The other problem with hoses is that even though they look perfectly fine on the outside, they can collapse internally so that little or no fluid can flow through them.
You end up with a situation identical to your own heart where the arteries can block. That is, atherosclerosis.
If the hoses are 15 years old then they could already be damaged.
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ErikJohanThomas
- Posts: 2
- Joined: 25 Apr 2025, 23:51
Re: Breaks
Thank you for all very interesting answers. I bought the master cylinder from a company in Berlin dealing with Lancia Parts. I Will consult my friends about where to begin.
Re: Breaks
Good useful posts.
For the rubber hoses we figure 5 years max shelf life and 10 years max under the car.
I would go back to standard DOT4. That is in the books. Less chance of mistakes. Don't forget to replace the force limiter with new.
Replace the O rings of any new master brake cylinder with EPDM O-rings. We sometimes get a batch with O-rings which are not petrol resistant.
For the rubber hoses we figure 5 years max shelf life and 10 years max under the car.
I would go back to standard DOT4. That is in the books. Less chance of mistakes. Don't forget to replace the force limiter with new.
Replace the O rings of any new master brake cylinder with EPDM O-rings. We sometimes get a batch with O-rings which are not petrol resistant.
