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Discussion Starter · #1 ·
Well, never thought it would happen but that metal cap I tried to center in the picture is wet like it is leaking. Enough has come out to wet the line attachment nut right underneath. It doesn't look like a screw. I'm guessing a dealer would "need to replace" the whole master cylinder to solve it. I did a brake fluid change at 3 years with Valvoline Dot 3 / Dot 4. I'm also guessing may void the extended warranty we have....

Any thoughts please. Thank you.
 

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Well, never thought it would happen but that metal cap I tried to center in the picture is wet like it is leaking. Enough has come out to wet the line attachment nut right underneath. It doesn't look like a screw. I'm guessing a dealer would "need to replace" the whole master cylinder to solve it. I did a brake fluid change at 3 years with Valvoline Dot 3 / Dot 4. I'm also guessing may void the extended warranty we have....

Any thoughts please. Thank you.
You might pull the lid off again, and look for a pinched seal.
 

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Discussion Starter · #3 ·
Thank you for the idea. I wonder if anything there is serviceable, (openable), because I never touched anything in that vicinity.

The reasons I figured it was the master cylinder is that it looks like one with line coming out typical of them, the familiar unique outline/shape, and I traced the hose/tube on it all the way back to the brake fluid reservoir, which is on the driver side in the typical location. Looks expensive. Gulp...

(I was doing my best to do the 0 inspection as the car says "Service Due Now". Interestingly it was 0 1 8 for a while but as it got close A came on. I'm starting with 0 and gonna reset it and see if it'll give me some more time for the rest. This is what it usually does if I get the correct one that it really needs).
 

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Ah, sorry.
Thank you for the idea. I wonder if anything there is serviceable, (openable), because I never touched anything in that vicinity.

The reasons I figured it was the master cylinder is that it looks like one with line coming out typical of them, the familiar unique outline/shape, and I traced the hose/tube on it all the way back to the brake fluid reservoir, which is on the driver side in the typical location. Looks expensive. Gulp...

(I was doing my best to do the 0 inspection as the car says "Service Due Now". Interestingly it was 0 1 8 for a while but as it got close A came on. I'm starting with 0 and gonna reset it and see if it'll give me some more time for the rest. This is what it usually does if I get the correct one that it really needs).
How did you do a brake fluid change without taking the lid off the master cylinder?
 

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Discussion Starter · #6 ·
It is some sort of reservoir, but it is not the main reservoir that you service. (It doesn't have any sort of cap that you can open as far as I know). I wonder if the engineers decided to make the remote reservoir and place it in the typical location so nobody mixes it up with some other fluid?...
 

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Interesting that it happened after a brake fluid change.

When I got the service reminder (A12), my mechanic took a look at the brake fluid and measured the hygroscopic level and found no contamination nor water so after 45,000 miles, he said the fluid is still factory fresh condition.

Still running the original brake fluid - amazing Honda technology!
 

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Discussion Starter · #8 ·
The brake fluid change was last year so not immediate leak. I did use a Dot 3/Dot 4 labelled fluid if that matters. 😬

(I think I reported here that I found some precipitate in the fluid that came out. I'm not sure a standard test would find that. I hope someone else is brave enough to get another person and do the manual bleeding that I did to either confirm or refute that my condition was unusual. I've never seen precipitate in brake fluid flushes I've done)...
 

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Discussion Starter · #9 ·
I kind of forgot to share that my wife has a propensity to slam the brakes for what I deem as unnecessary/ my son deems as extra cautious, many times, in a single trip. I'm going to assume that this eventually culminated in this leak.
 

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Nope slamming the brakes should never cause a leak.

You wrote metal cap? Not sure what you are referring to, do you mean the flare nut for the brake line?
That is not likely to leak but putting a wrench on it to check would not hurt.

It almost looks like it has run down from the reservoir, there are 2 rubber seals in the mc you stick it into, however they usually never leak.

I would spray some carb cleaner on the area let it dry and start monitoring where the fluid is coming from.
 

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Discussion Starter · #12 ·
Sorry for the late response my wife wanted to go out this morning. Sitting in the waiting area of a restaurant going to bring food home.

Just above the flair nut metal brake line there is a "black" (verified with my wife what color it is) round thing. (I called it a cap because I'm afraid I have no idea what it is nor it's function). It initially looks a little wet in the lower left which may spray like that.

I'll wipe off the area and try to observe...

Thank you everyone for the input.
 

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Discussion Starter · #13 ·
I just got home and immediately popped the hood and took a look. The leak looks like it is getting worse and appears to confirm my suspect that it is leaking from the junction between the black round thing and master cylinder.

 

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I just got home and immediately popped the hood and took a look. The leak looks like it is getting worse and appears to confirm my suspect that it is leaking from the junction between the black round thing and master cylinder.

The black round thing you are referring to is just a rubber cover for the bleed screw under it, pull it right of and look
 

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Discussion Starter · #15 ·
Wow. Looked metallic until I touched it to remove it. I subscribed to techinfo.honda.com and after a little while found the torque spec to be 6.9 Nm. I had minimal room to rotate the wrench but eventually reached 7.1x Nm and stopped.

Thank you!

There was a little fluid pooled in the cap, it definitely looked like the source.
 

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Wow. Looked metallic until I touched it to remove it. I subscribed to techinfo.honda.com and after a little while found the torque spec to be 6.9 Nm. I had minimal room to rotate the wrench but eventually reached 7.1x Nm and stopped.

Thank you!

There was a little fluid pooled in the cap, it definitely looked like the source.
You would think that there would be pretty specific quality control around the torquing of that screw and the likelihood of it working loose would be pretty slim. I assume if that thing opened up completely you’d have no brakes. Of course with a hybrid the situation may not be quite so hopeless.
 

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Discussion Starter · #17 ·
I wonder why it took coming 60k mi to start leaking. It definitely needed some tightening but I could barely turn my GearWrench 120XP torque wrench 1 or maximum 2 clicks each ratchet. I would guestimate I got 1/8th turn to 1/4 turn for the wrench to beep solid. There is definitely some level of inaccuracy in not turning it continuously. It doesn't click, just beeps so it's quite difficult to get it exact as well.
 

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I wonder why it took coming 60k mi to start leaking. It definitely needed some tightening but I could barely turn my GearWrench 120XP torque wrench 1 or maximum 2 clicks each ratchet. I would guestimate I got 1/8th turn to 1/4 turn for the wrench to beep solid. There is definitely some level of inaccuracy in not turning it continuously. It doesn't click, just beeps so it's quite difficult to get it exact as well.
It might have worked itself loose from thermal expansion/contraction over the years.
 
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