1994 Civic LX 1.6L Master Cylinder (ABS)

[Gito]

Friend owns a 1994 Civic LX 1.6L Master Cylinder with ABS.

While driving for at least one block and coming up to a stop light, the brake pedal sinks and seems to slow the car down just a bit.
After quickly releasing the brake pedal and re-applying pressure to the brake pedal, the car stops without any problems.

To me this sounds like a classic Master Cylinder (MS) problem.
My friend also told me that he thinks that he might of poured power steering fluid into the brake reservoir a few years ago. He's not sure.
He added that this brake symptom has only been happening for a few days.

I told him that there could be air bubbles in the system and that we should try bleeding the brake fluid first.
If we get no air bubbles coming out of the bleed screw(s), we can then proceed to replace the Master Cylinder.

Any other advice is greatly appreciated.

 

[researcher]

definitely sounds like not only old brake fluid, but it could have a leak, letting air into the system. I've had this feeling before on my civic, not as bad as you've described though.. when it's happened, I'm about 3 years into the brake fluid, time to change it!

Change it, re-bleed the brake system, and all is well again.

But.. you'll have to check everything, every hose, hard line, connection, etc.. then after that's eliminated then you could probably test out the master cylinder for leaks. It's a 94! Nothing lasts forever.

 

[mk378]

Adding an oil-based substance to the brake fluid would have caused serious problems almost immediately, not years later.

If there were air in the lines, pumping the pedal would not help you stop.

Should just need to replace the master cylinder. Avoid "duralast" and similar cheap parts-store units.

 

[Dave Sherman]

Originally Posted By: Gito

My friend also told me that he thinks that he might of poured power steering fluid into the brake reservoir a few years ago. He's not sure.


Ooooh... Not good. Anything oil based will swell all the rubber seals in the brake system, usually ruining them eventually.

 

[nthach]

Originally Posted By: mk378
Adding an oil-based substance to the brake fluid would have caused serious problems almost immediately, not years later.


A friend did this and the damage happened a year later. It does take a while for a petroleum product to mix in with the existing brake fluid and migrate through a closed system.

At a minimum, you need a new master cylinder(OEM Honda or a Nissin one if you can find it), new rubber lines and new calipers/wheel cylinders all around. Honda also used a weird ABS system - the normal service braking circuit is augmented by the ABS circuit - the ABS portion has its own fluid supply. If that went out, supposedly someone on the NSX forums was able to rebuild it.

 

[Gito]

Do we have to disconnect any electronic component to properly bleed the air out of an ABS system or can we pretty much drain the brake fluid, add new brake fluid and start bleeding the air out. Do we have to bench bleed the Master cylinder?

 

[mk378]

Bleed that system as if it were conventional brakes. You don't have to do anything with the ABS unit unless the ABS unit's separate reservoir has run out of fluid.

 

[Gito]

I will have to look for the separate reservoir under the hood.

 

[mk378]

It would be on that big thing underneath the battery where all the brake lines converge. Although I didn't think there were any 1994 LX with ABS, only the EX.

 

[Gito]

Genuine Honda Master Cylinder is no longer available.
How is Centric?

Also need outer driveshaft boot. Should we go with Moog/Precision or Beck/Arnley?

 

[nthach]

On older Hondas, the ABS module can't be missed - it's by the radiator with its own fluid reservoir.

As for the Centric MC, I can't imagine it'd be any worse than a new Chinese-made Cardone or Beck. Taiwanese quality is certainly better than Chinese quality.

 

[Gito]

We want a good Master Cylinder. If anyone here can point us to a good quality MC we will jump on it.

 

[Gito]

We ordered the Centric MC, 4 Centric brake hoses and an outer drive shaft boot but Moog.
We figure that if power steering residual is stuck in the brake caliper channels it will eventually makes its way out into the MC again. Better for a $53 MC to go out again than an expensive better quality MC to go out. We hope this solves the brake issue.