The pedal is soft. (I let the the reservoirs evaporate). I am going to drain and replace. I'd like to use a Mityvac to draw fresh fluid from the reservoirs through the bleed screw, instead of the conventional way. Here are the questions:
Work shop manual says to have engine running (using the conventional method)when applying pressure to brake pedal. I would imagine this is to keep the pressure warning valve centered. Since I am not using this method does the engine need to be running?
Any reason not to use the Mityvac method?
Any other known cautions with the method and in general?

Thanks, Tim Flynn

Submitted by NE52-32043 on Thu, 04/29/2004 - 11:46

I agree with William on this. Fluid does not evaporate. You must be leaking from somewhere. Check the hoses from the reservoirs and the clamps. If you have the original yellow-line tubes, they are 30 years old and could be porous. If they were changed, but not with proper hose, the brake fluid will deteriorate them. Get proper replacement hoses from one of the usual suspects. I recently bought them from Welsh Enterprises (NAYYY).

Cleaning out the reservoir is important. Just use regular soap and warm water, and a bottle brush. Check to be sure the plastic is not cracked, and dry thoroughly before refilling. The method William described works well.

Be very careful about pressing the brake pedal more than half way. Scale can build up in the lower part of the cylinder, since it only goes about half way under normal braking. If you push the pedal all the way to the floor while bleeding, it can chew up the seal and then you're looking at a rebuild.

BTW, if you can't locate the leak, check inside the foot well, under the carpet. It could be the seal in the master cylinder leaking.

Steve Weinstein, JTC-NJ
'72 E-type 2+2
'70 XKE FHC

Submitted by bonnettoboot@e… on Wed, 04/28/2004 - 14:58

Brake fluid does not evaporate, it has leaked out and the residue mixed with moisture from the air has left a mess. BE CAREFUL when bleeding as the cylinders are most likely dry also and pushing the pedal with no resistance will likely do more damage. My advice after cleaning out the reservoirs is; Open the right rear bleed nipple and fill the sustem with fluid, allow the system to gravity feed and drip out. close this nipple and open the left rear and do the same, then the right front then left front. (presuming it is a left hand drive car). Now fit your pressure bleeder and follow the instructions. The engine may need to be running for final bleeding as sometimes it is the only way to get full travel of the servo cylinder, but only as a last resort

Jaguar affectionado and etc.