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MG TD TF 1500 - Brake Bleeding Problem

I recently replaced all my corroded wheel cylinders and along with having my MC rebuilt by White Post. I have bled the system several times but still can't get any pedal pressure. I have no bubbles at the bleeder valves. I'm beginning to think about the MC rebuild. One thing I notice is if I have the cover off the MC and pump the brake pedal couple of times, brake fluid shoots straight up out of the MC in a stream about the width of a pencil. Will a correctly functioning MC do that? Is there any easy way to check if the MC is working?
Joe Holtslag

You probably have your brake adjusters backed off. Tighten up each shoe so the drums are locked and rebleed. If the shoes are slack there is insufficient stroke in the master cylinder to push all the air out. Trapped air is compressed and this is what creates the fountain in the master cylinder reservoir.

Good luck

Jan T
J Targosz

Jan, before I started bleeding I tightened all the adjusters up tight and then backed off each one until it was dragging. Then I bled the brakes. Do I need to bleed it with the adjusters down tight and then later back them off? Thanks.
Joe Holtslag

Loosen the line out of the MC and see if you can pump some fluid out of there. Did you bench bleed the MC before install? I have seen that little jet of fluid before and don't think that is a problem.
George Butz

Hi Joe,

I had exactly the same problem until I locked the brakes up hard before bleeding. I got my wife to push the pedal down after I had opened a bleed nipple and she kept it down until I had closed it off. I had to do it this way since her arms are not long enough to press the pedal and open the nipples at the same time! Seriously though I have automatic nipples on my TF and they didn't work neither did putting the end of the bleed tube in a jar of brake fluid and letting the air bubbles escape through this. I think air was leaking past the loosened nipples.

Jan T

J Targosz

Joe, try barely cracking all the bleeders and let them drip for a while making sure to not let the reservoir run dry.
I had the same problem with a VW Beetle and this solved the problem.
Rich (TD 3983) Taylor

I just refinished rebuilding my brakes - every single cylinder, hose and line, except the master cylinder - and after completing the last brake bleeding my brakes were still pretty spongy. Once I read this thread I realized what I had done wrong; I had bled them without locking up all four wheels at maximum brake adjustment, which left too much 'play' in the system. So today I locked up each wheel as tight as I could, bled the brakes again, and presto! my brakes are now 100%... or at least as 100% as MG drum brakes ever get... very nicely responsive!
I wish I had read this BEFORE bleeding my brakes and reassembling everything.
I suppose I can at least say I've gotten very FAST at whipping off the wheels and doing the brakes...
Thanks again to all for all the input that helped me through this!
Now back to tuning the carbs and getting the idle right...
Geoffrey M Baker

The saga continues....
I locked each set of brakes up tight, bled them again and presto--still no brakes. I can pull clear fluid from all four wheels. I did this whole thing 20 years ago when I restored the car and it really wasn't this difficult. The only thing different now is that I don't have a "pedal pusher" to help me, so I am using one of those vacuum sucker thingys available from Moss. This pulls the fluid through the MC instead of the MC pushing the fluid to the wheels. The MC works somewhat because if I crack open a rear bleeder, and use a long stick to push on the brake I can force fluid out of the bleeder.
To me it acts like the MC cup is worn, missing or incorrectly installed. I find this hard to believe on a White Post rebuild. I suppose I could adapt a oil pressure gauge if I knew what an acceptable pressure was. Ideas?
Joe Holtslag

I was not able to use the vacuum bleed system - it just sucked in air at the bleeders... Try the old way... Hook bleed up with a hose into a jar and pump the pedal till no more bubbles shoe up...
Geoffrey M Baker

Joe, it's been my observation that those bleeders do not work on our cars. Unless the pedal is depressed there is no open orifice for air to replace the fluid trying to move in the master cylinder. It's like trying to drain the water out of a hose that's still connected to a faucet. Bud
Bud Krueger

I did my brakes several years ago and also changed to silcone fluid. I had the MC redone and I can't remember which company, but I bench bled the MC and there was a leak while doing this. I took it apart and there were fine score marks in the barrel. I removed these with very fine sand paper and everything has been fine since. I might have even posted a note at the time on the bulletin board.
Ron Coates

Sorry for typo, I meant show not shoe; but hey it works, brake "shoes" right?
Anyway, I just googled a couple of youtube videos on DIY brake bleeding, and made myself a jar with a piece of brass pipe in the top, and took three feet of clear hose and connected it to bleeder and jar, and was able to bleed the brakes single handed by looking under the car at the jar as I pushed the pedal... if it kept bubbling I would tighten the bleeder screw down just a tiny bit... finally no more bubbles.

Geoffrey M Baker

There are single handed operation brake bleeders in the market place, they do work.

This not an expos ay on "how to suck eggs" however it may resolve your problem.

The old true and fast statement regarding brake bleeding was that you did the brake with the longest connection line first, then migrated down until reaching the shortest run.

If you have an assistant,the pedal pumping process should be done with the bleed nipple closed. After the pumping process, the assistant maintains pushing the pedal to the floor whilst you crack the bleeder and re tighten it prior to the assistant releasing the pedal. This negates air entering via the nipple thread.

This is repeated until when you crack the nipple no more air is expelled.

I havent attempted this with my TF so it may not be viable. On my Volvo after exchanging the brake fluid I adapted some fittings so I could apply air pressure to the top of the MC reservoir, a very fast method to bleed the system.

G Evans

This thread was discussed between 09/04/2014 and 19/04/2014

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