so today i was limping my blown 88 GX to a shop in delta for an engine swap, and when i was at the shop i noticed the brake pedal is very firm and offered very little braking power.

i was looking at my temp gauge alot throughout the 8km trip, stayed at 1/4 on flat roads a 1/2 going up hills. So i dont know why it would boil at normal operating temps.

or could it be that my filler cap? the gasket in it is useless cuz its soo worn that it doesn't seal coolant and steam comes out from the hood and under the car. Could the steam heat from the leaky filler cap make it boil? Or is it also because of a poor brake bleed job? I don't think so but it might be, but braking was good before it started to boil

 

hmm i think it might be the steam... if not.. you got one hell of a weird serious problem

 

So, let me get this straight, Your brake fluid was boiling correct? What type of Fluid are you using? were you riding the breaks a lot? Cause, ive seen brakes get red hot on touges before... but never seen the brake fluid get that hot.

 

If the pedal is firm but no braking power you've cooked your pads. Could a caliper be stuck? If the pedal is spongy then you've boiled moisture out of your fluid and created air bubbles.

 

hmm im now pretty sure its the brake pads, my hand brake was more effective before i got to the shop, also cuz the the calipers are seized and drag a bit but not a lot. Put that should be easy to fix i could just take out a shim so it doesnt drag.

But i still don't know why the pedal was extremely stiff

It can't be the steam, my Clutch master and slave cylinders are fine, im pretty sure its the seized calipers that fucked to pads.

i was using dot 3

 

Ok... what you just described is very confusing. You said that the pedal is firm (more firm than usual) and it you can stomp the pedal all you want, but the car doesn't want to stop too easily? That could easily be a booster problem. But.....

You're also stating that the brake fluid is boiling!? Brake fluid (that is not completely water contaminated) boils at somewhere around 400degF! Steam from the engine won't cause that. Now, calipers are supposed to drag some, but not very much. How did you determine that they were siezed? If they are siezed, then that's probably the entire problem. If you can't force fluid into them, then the pedal will be very stiff. If they're stuck and dragging the rotors, then the dragging friction will cause heat buildup so badly that it will boil the fluid. What you're probably facing at this point is:
1) Replace frozen calipers
2) Replace pads. They've glazed by now and become useless.
3) Replace rotors. You've probably overheated them and caused stress fractures all over the faces.
4) DON'T NEGLECT to flush the fluid! It's recommended to do every 2 years anyways, since DOT3 is hygroscopic (meaning it absorbs moisture)
5) Check all the lines and make sure that there aren't any clogs or leaks. The rubber flex hoses should be .... well.... flexible, and shouldn't show many cracks when you bend them.

 

o sorry i meant to ask could the steam from the filler cap made the fluid boil, but now its not really a posibility since my clutch cylinders were fine.

and i just flushed the master cyl a weeks ago, and did some panic stops and it was fine, of course that was when the brakes weren't overheated