Here is a stumper that I haven't been able to figure out.

I have a 91 accord wagon. After running the A/C for about 30 minutes I lose my brake pedal. I can stop by pumping it but otherwise it goes straight to the ground.

My first thought is that it is master cylinder but why only after A/C and otherwise never a problem.
Could it be vacuum and the brake booster buy vacuum is not related to A/C.

I know my left front caliper needs replacing because it pops when I stop. I know it is not my axles causing sound.

Fluid is good and I have had new pads and turned the rotors late last summer.

My engine burns oil and runs very hot which could cause alot of heat to everything in the engine bay and I am wondering if this could cause deterioration of my brake fluid.
Also when I run my A/C the rpms at idle rise to about 2500 and this is when my brake pedal loss is most noticeable.

Otherwise I am really stuck and have never seen anything like this. Has anyone ever heard about this before?

I am open to suggestions but I am replacing the motor in the next few days. I have another one already built for an easy swap but I fear this won't solve my problems. I am only replacing the motor due to 256k miles and adding about 1 quart of oil every 3 days. It is cheaper to replace the motor since I have one rebuilt sitting in my garage.

Thanks in advance

 

My clutch pedal does the same thing...I thought that it was the slave cylinder, but I replaced that and everything is good until I run the A/C for a while, then it hits the floor and releases really early. WTF?

 

Ok this leads me to believe that maybe the oil is overheating maybe and losing consistency causing a weak pedal?

Still looking for some info on this.

Desert-Honda where are you?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by sauceja &raquo;</TD></TR><TR><TD CLASS="quote">I know my left front caliper needs replacing because it pops when I stop. I know it is not my axles causing sound.
</TD></TR></TABLE>

Explain this popping? Calipers usually don't pop...they tend to seize up?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by sauceja &raquo;</TD></TR><TR><TD CLASS="quote">My first thought is that it is master cylinder but why only after A/C and otherwise never a problem.</TD></TR></TABLE>My '95 Integra did that, because it gets hotter in the engine compartment when the AC is running. The pedal would smoothly sink to the floor. A new MC fixed it for me.

 

When I come to a complete stop my left front caliper when go CLICK. and then when I start to move forward it will go click again. I haven't looked to far into it yet. I started prepping the engine tonight to pull the engine. I just had a heater hose go today as well. Yeah this is one rough Honda. 256K miles and pretty sure zero maintenance in the last 5 years.

I have put a new timing belt, balance belt, water pump, front engine seals, radiator hoses, oil and valve cover gaskets. That is about it in 2 years that I have had it.

 

doubt has anything to do with the aircon!
i spent 2 years with this increasing intermittant problem until petal caused thump and went to floor. the month before i had bled my brakes, and i guess the mc seal -or shaft was worn-finally gave up.
also, if someone pushed down on petal-with engine off- i could hear brake fluid inside the mc. make trickling sound of death-bypassing the seal.
oh yes, my '95 is low mileage at 60k miles. get a new honda oe mc. or a new adler,nissin, or ntp oem mc.

 

Yep, I think I will try that first. I have been debating getting one anyway. But since the wife and kids are going to start driving the car I want it to be flawless.

Well, mechanically anyway.