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MG TD TF 1500 - Loss of Brake Fluid?

Follow on to my previous thread.

I normally drive my TD at least once per week. However, this summer due to excessive outside temps, I have not driven her much. Recently when I took her out, I noted excessive brake pedal travel. I stopped in the driveway, and checked the fluid level and it was low. Using my special Haagen Dasz wooden ice cream stick marked at 1/2" intervals, I filled the MC to the proper level. I pumped a few times and all was well.

Well, that was two weeks ago, and the pedal movement is excessive again. There is no evidence of leakage on the garage floor either under the MC or at the wheels. Hence this question. When filling the MC to proper level, should the brake pedal be pumped a few times, and the level checked again? I did not recheck when I last filled it, so I am curious. If no recheck and not adding more fluid is normal, what might my problem be, and where should I be checking?

TIA

Larry
L Karpman

Hi Larry, if the fluid is low it has to be going somewhere, usually through a leaking wheel cylinder.

If there is no air in the system, then topping up the master cylinder will not make any difference at the pedal.

I think that in your case the fluid level has dropped due to leakage, allowing a small amount of air to enter the system. This explains the symptoms at the pedal.

You should remove the brake drums and inspect the wheel cylinders for leakage. Chances are that there is fluid on the brake linings anyway and this is critical for brake efficiency.

Also the pistons seize up in the wheel cylinders. This will have to be checked as well. I have found that I need to do this check every two years to keep my brakes efficient. If you find that there are seized up wheel cylinders you should get back to us as if you try to force them out you will bugger up the pistons.

Hope this helps,

Paul.
Paul van Gool

I agree with Paul...when I was losing fluid I kept looking under the car and nothing...then I finally pulled a wheel and there was fluid inside the hub...brake lining soaked! Bad wheel cylinder...
Bob Doc
Bob Dougherty

Bob/Paul, I agree. But what if, by some slim chance, when I check the fluid level in daylight tomorrow morning I find no loss of fluid from the last topping up? Obviously this would mean air got in the system, but how would it get in if there is no leak? Or, am I just fooling myself thinking the level will not be lower than two weeks ago?

This will be my first adventure into drum brakes, but with all the info from the archives, the forum and all the helpful members, and the WSM, I'm sure I can get the brakes up to snuff.

Cheers

Larry
L Karpman

Bob/Paul, I agree. But what if, by some slim chance, when I check the fluid level in daylight tomorrow morning I find no loss of fluid from the last topping up? Obviously this would mean air got in the system, but how would it get in if there is no leak? Or, am I just fooling myself thinking the level will not be lower than two weeks ago?

This will be my first adventure into drum brakes, but with all the info from the archives, and the WSM, I'm sure I can get the brakes up to snuff.

Cheers

Larry
L Karpman

Hi Larry, you need to pull the drums regardless as there is a problem and it won't go away. You need to do this for safety. If there is no leaking fluid and all the wheel cylinders are working correctly at least you now know and can look elsewhere. (I have never done this check without finding something wrong.)

Cheers,

Paul.
Paul van Gool

paul: I agree. Thanks again

Larry
L Karpman

Found my leak! It's the master cylinder. I keep a litter box under the car, and was certain that any drip from the cylinder would fall on the floor beside it. I was wrong! I moved it over yesterday, and today there was a small puddle of brake fuid directly under the master.

I'd like the advice of the forum as to whether to use White Post or others to rebuild, or to buy an aftermarket from the usual suspects. Only one I won't accept is one made by County, after the absolutely horrible time I had with one of their water pump castings.

TIA

Larry
L Karpman

This thread was discussed between 12/09/2009 and 15/09/2009

MG TD TF 1500 index

This thread is from the archive. The Live MG TD TF 1500 BBS is active now.