[709]

Ok so I think i've figured out my break problems.

IT's an intermittent problem.. only happens when its cold.. sometimes the slightest tap on the breaks locks them up..

So, unless there's a constant something or other or a regulator..

When the engine is cold, the manual choke is closed.
The break booster runs off vccume..

So theoretically, with the choke closed the and engine sucking air, it'll pull air from the booster with mire vaccume then when the engine is warm..

Am I right? Or completely off-base?

 

[Jim_Lou]

I think you're off base. The booster is as big as it is because it's a reservoir. There's a check valve that holds it at the highest vacuum the engine ever achieved. If you rev the engine and close the throttle, there is as much vacuum available as there ever will be. And, unless the check valve is bad, it will be there until you use the brakes.

You probably have a booster problem; maybe a broken spring in the valve mechanism. I haven't had a booster apart for years. Maybe somebody who has can help out.

 

[GeeAea]

Easy way to eliminate any further exploration in this direction ......

Warm engine completely before ever applying brakes for the first time for the day (choke is now open). If it doesn't do it ..you may have further issues in the brake booster or at least with your engine vacuum. If it still does it ...then you need to look at other parts of the brake hardware.

This just eliminates the "cold engine" part of the theory

When you say "lock up" ...do you mean all 4? ........or just the rear?

 

[CJ7Taz]

First, I would try bleeding all the lines until they are all the old fluid is flushed out. You could have some moister forming ice crystals causing the problem. There are valves to keep a little pressure on the system and to allow the brakes to be pumped up. A little ice could further block the fluid return.

It's cheap and easy to do if you gravity bleed the system and should be done from time to time anyway.