8 replies to this topic

[brandondonat]

I changed my engine this past weekend and took it out the bottom of the car attached to the front subby. In doing this I disconnected the brake lines and everything holding the subby on obviously. Engine is running like a champ now except...

... the brakes are very spongy. I have used 2 bottles of brake fluid bleeding the brakes (exactly like the Haynes suggested). It is a dual circuit (yellow tab) master cylinder setup. Before I had changed the engine the brakes were working like a champ.

Something to think about.... I put the other engine in on its subframe.. not the original subframe. So, everything from the line that attaches to the brake regulator down is from a separate mini. There is no signs of leaks through the calipers or anything and there is no leaking through the rear cylinders. The master cylinder had fluid in it the whole time the engine was being changed.

I am thinking that the master cylinder seals have gone with the release of pressure from the brake system. Have any of you seen this before? ANy feedback would be appreciated if it could save me some time.. am kinda pressed at the moment. Cheers. -Brandon

[Guess-Works.com]

Do you have to pump the brakes to get any resistance ? or is it just a lack of feel ?

What I would then do is start undoing the brake lines and using a couple of old lines with connectors, block the lines to the rear, then you can concentrate on the front circuit, islolate parts of the braking system that way you will be able to fault find the system.

[brandondonat]

I have to pump the brakes about 5-7 times before I have any pressure on the pedal. After jacking up one side of the car (both front and back) it took about 2 pumps before I could no longer turn the front wheel but about 10 pumps before I could not turn the back wheel. When you release the pedal again it goes back to the normal spongy brake feeling.

I have no idea why I did not think of something like that troubleshooting method.. pretty much common sense to do but I overlooked it. I will have to start with that and move on from there.

[Guess-Works.com]

hmm, have you adjusted the back brakes ? and could be an air lock front to back, bleed order on a front to back split should be rear n/s, rear o/s, front n/s, front o/s.... if you can get hold of an eezibleed kit, they make bleading brakes some much less hastle. Clicky

[brandondonat]

The back brakes were adjusted very well before the problem. I actually just changed the rear shoes out a few days earlier and I also changed the rear n/s cylinder because the bleeder nipple broke when I tried to bleed the brakes. The rear wheel cylinder was changed after I already had the brake prob.

I just trook my lunch break and pulled a master cylinder out of another mini.. hopefully it will not resort to this, but if it does.. I will at least have one available. I will also try to bleed the brakes like you had just said.

[brandondonat]

I just re-read your last message that you inserted. I had to think about it for a mini since mine if a left hand drive mini. The way you explained is exactly how the Haynes manual explained. Except for the left hook minis it is rear f/s, rear n/s, front f/s, front n/s. This is because the master cylinder is on the left hand side instead of the right.

I am wondering if I should cap the lines like you suggested and work my way forward to make sure that I get good pressure from the master cylinder. There really isnt much to change... I would think the calipers would leak if the problem was there... but no sign of leaking.. anywhere.

[Guess-Works.com]

One more thing... make sure you have the calipers on the right way up, bleed nipple at the top.... was fault finding on a mates, it wasnt until we came to put the calipers back on I noticed he had had them on the wrong side... DOH :nugget:

[cowboy]

i had a similar problem when i rebuilt mine, what you have to do is to bleed the top pipe on the master cylinder, just open teh union, and get someone to press the pedal, lock it when the pedal is down, repeat until you have just fluid with no air coming out, then proceed to bleed teh brakes as normal


:wales:

[brandondonat]

I did notice when I was bleeding the brakes that one of the calipers piston was on the bottom of the caliper. It was the n/s caliper. I am going to have to have a look at one of my other minis to see if they are both pointed up... that is the correct way huh? That is news to me... I didnt even think about it. Why would that cause this problem, is there something internal?

Will try that this evening cowbow... just to clarify... I only disconnect the top line and then push the pedal down and before I let the pedal up I close the nipple. Basically it is bleeding the master cylinder is what you are explaining correct?