Loss of brake fluid
 

Yesterday I noticed what felt like a lowering of the point where the brake pedal took pressure on my '67 250SE. I have been driving a number of different vehicles lately so wasn't sure that it had changed.

However today it definitely was suffering a loss of pedal pressure, and checking the reservoir I found it next to empty on the brake side.

http://i1349.photobucket.com/albums/...psf46cda38.jpg

Trying to see where it had been leaking from was hard - there is some oil that leaks slowly from various places so there are numerous 'damp' sections... however I noticed behind the right front wheel a wet looking section at the back of the wheel arch.

http://i1349.photobucket.com/albums/...ps6fff93ae.jpg

The only thing I could see that looked like a leak above this was the rubber seal between the hose attaching the reservoir to the brake servo. It looks pretty dead...

http://i1349.photobucket.com/albums/...ps8ec5ca0a.jpg

But would this explain a loss of brake pedal pressure? Would it need a leak further down the system for the fluid level in the servo to drop enough so that this leak would cause trouble?

Due to space considerations it appears that the brake reservoir(s) are remoted in RHD cars. In LHD applications the reservoir(s) are mounted directly to the master cylinder (aka, servo). The rear half of the reservoir(s) supplies the rear brake circuit, the front half supplies the front circuit. [Which half supplies the clutch circuit? The front?]

Look to the connection from reservoir to master cylinder as one possible leak point, also examine all the brake hydraulic lines that connect the master cylinder to the rear brakes for leaks, and the rear calipers.

Hi Frank

Thanks for your reply. I have had another look at it and you are right. I had mistakenly thought the front section of the reservoir supplied the clutch and the rear the brakes, but I see now that the front supplies the front brakes and the rear the rear brakes, just as you say. Its hard to see under the reservoir and i missed the second (front) hose connected to the servo, and had thought the hose that goes to the 'trap' (haven't worked out what that is yet) was heading off to the clutch master...

I cant see any other leak at this time, and have topped up the reservoir, and pumped the brakes a few times with the engine running to see if I could spot further leaks. Nothing - but maybe the lines would have to be bled first to get fluid to the rear wheels first?

Anyway, I'll see if i can get a new seal for the hose to the servo, and take it from there. Thanks again for your reply.

Yes, you need to bleed the air out of the lines. When the seals go crappy, it's a good idea to replace or rebuild the master cylinder too.