Brake lines keep pressure after releasing pedal

[Gilberto]

Hi to all of you from Mexico.

I noticed that even in slopes, my Lightweight did not move by herself, so brakes service.

What I found is that brake lines keep pressure after brake pedal is released.

Can anyone help with suggestions?

Cheers,

G

[SafeAirOne]

1) Make sure the push rod on the brake master cylinder is the correct length/correctly adjusted. If the rod is in the master cylinder too far, the valve won't open to let the brake fluid back into the reservoir when the brake pedal is released.

2) Make sure the return spring on the brake pedal is not broken and that the pedal returns all the way up when the brakes are released.

3) Drive around for a while, then feel each wheel to see which one or ones are hot. Check to see why the hot wheels have sticking brakes.

If just ONE rear wheel is hot, it's probably a sticking wheel cylinder.

If BOTH rear wheels are hot, there may be a problem inside of the rear flexible brake hose.

If ONE front wheel is hot, then I'd look for a sticking wheel cylinder or a problem inside of the flexible brake line.

If BOTH front wheels are hot, or ALL wheels are hot, then I would have a look at the master cylinder.

[Gilberto]

Thank you.
As soon as rain quits I will use your checklist and post results.

Cheers,


G

[Gilberto]

A short update.

Checked rear flexible line, it was blocked.
Besides left rear cylinder has a very small leakage.

Next week we will install the new flex line and test.

Cheers,

Gilberto

[yorker]

Was it swelled shut or was debris in it? I've seen older lines swell shut, either from age or from the dreaded incompatibility with modern brake fluids.

[Gilberto]

It was swollen, something like atherosclerosis, if I might use the expression.

I have a query: If I replace these lines with modern ones, then I assume that I can use any, or almost any brake fluid. Am i correct, or next victim will be both masters clutch and bake?

Thank you for your comments.

Cheers,

[yorker]

I don't think anyone can say with certainty. In the USA we always insist people use Castrol LMA brake fluid to avoid the issue. I've experimented with parts new and old in other brands of brake fluid and never really found a rhyme or reason to it. To avoid issues I use silicone brake fluid.

[Gilberto]

Ever since Gwen has belonged to me I have only used Castrol LMA, but I am running low, a little over a quarter now.

I live in Mexico, so I will have to source it locally.

I will update next week.

Cheers and have a happy weekend.

[cedryck]

If one wheel is hot it is most likely a wheel cylinder, or overly adjusted brake pad cam. Poorly over adjusted shoe cams will create heat as well ,

[Gilberto]

Thanks Cedryck.

I think that we have isolated the problem, it was a swollen flexible line, rear, just waiting rain to stop and change it.

I will report results.

Cheers,

[Gilberto]

Hi again.

Changed rear flexible line and everything seems in good order. I could not get synthetic fluid in Mexico, but a friend was in Texas, I sent him a picture of Castrol, he went to Autozone and found only Valvoline Synthetic, he grabbed 3 qt. Will it be OK?

Cheers and happy weekend.

G

[SafeAirOne]

Castrol LMA has been synthetic for a while now, not the vegetable oil-based fluid it was years ago. I think anyone using it at this point is doing so only for nostalgia purposes, presuming they can even FIND any nowadays. My area PepBoys auto parts stores stopped carrying it 2 years ago.


Valvoline synthetic should be similar enough to Castrol synthetic, I'd expect. Everyone who hasn't been able to get the Castrol for years seems to have replaced it with the Valvoline, judging from the results of a google search using "Castrol LMA vs Valvoline."

[Gilberto]

Today we got rid of most air in lines, adjusted each corned and now it is ready to go.
I feel more power, no wonder, rear end was permanently with pressure in brake line.
It pulls a little to the right when braking hard, but it is just a little.

Thank you for your help and advise.

Have a nice weekend.

Cheers,

G