Brake fluid leak

[Nick Bailey]

I have had my right brake reservoir empty out after a 2 week inactive period, twice in last 6 months. No trace of any fluid inside by pedals, and no leaking from brake reservoir. Also no signs of fluid under AC on hangar floor. No indication of worsening softness prior to event. Any one ever encounter this? Suggestions on troubleshooting from the more experienced are appreciated.

[rick bell]

sometimes that caliber get dirt in the inside. take of the calibers, remove the puck and clean, lubericat or replace the
"o" ring.

[Skymaster337B]

Sometimes the brake swivel fitting o'ring goes bad too. In that case, the fluid might drain inside the belly, where the main gear rotates.

[Ernie Martin]

I think you guys broke a new record. Someone asks for help, and he gets two responses in about 30 minutes.

[Dave Underwood]

Not to be out done, here is a third reply.

I think this is a problem specifically on G series aircraft.

I have this on a regular basis on my 78 FT337GP to point that I check the right brake pedal before I open the lower door.

When it is flat, I pump fresh fluid from the bottom of the caliber with an oil can full of hydraulic fluid and clear hose system I carry whenever I go on trips. A 1/4" wrench for the nipple is all you need.

We have checked all the fittings and all the various runs for leaks but to no avail. We have seen dried fluid in the hull area below the brakes but that is the only place.

The situation improved significantly when I replaced the bleed nipple with a new one. That is the first recommendation. That nipple fits into a larger one. Replacing that would be the second recommendation. Both are standard Cessna parts and normally pretty widely available.

I am suspicious that it is the parking brake system. The right reservoir is higher than the left and I think fluid is drawn to the left across the parking park control, made worse when the brake lever is not in the fully up position. We did replaced the parking brake control unit a couple of years ago and once again it helped, but did not cure the problem.

I have the original somewhere and have just not had time to take it apart and check the seals. The replacement unit had a 1970's date on it, so I should not be surprised if the seals on the replacement unit wher dried out.

The third recommendation is to rebuild the parking brake control unit.

The final recommendation might be to put a spring on the lever to make sure it stays in the fully up position.

That's my two cents worth. Please let me know what you end up finding.

Now has anyone had low airflows out of the defrosters?

Regards - Dave

The problem seems to be less when I excercise the parking brake as an FYI.

[Pete Somers]

We have just had to change all the flex pipes from the foot motors as one of the pipes have a pin hole in it. But it did not show until the pedal was moved.

Pete

[askycobra]

This is for my 1969 337D. In my case the right brake would go flat and the left would stay up. As in an earlier response the problem was traced to fluid seeping through the parking brake control. The right master is higher than the left and fluid was gravity flowing through the (unset) parking brake control and seeping out the top of the left master and puddled in the belly. A couple of O-rings and the problem was solved with a parking brake rebuild.