billy hellcat Posted October 23 Report Posted October 23 Anybody have brake fluid leak from belly? Took off panel on belly and can't seem to see where it is leaking. Pumped the brakes a few times and still can't find the source. Just wondering if it's a known issue. 1999 ovation. Thanks
Fritz1 Posted October 23 Report Posted October 23 take the panel below the master cylinders off to see if anything is dripping, chances are the O-rings are leaking, I resealed the pilot masters on my 2000 Bravo this summer, same story, most important thing to do after reseal is to submerge the cylinders in 5606 and pump them back and forth a gazillion times until absolutely no bubbles come out, then fill the system from the bottom and connect the masters without introducing any air
Aerodon Posted October 23 Report Posted October 23 There is a long line from th brake master cylinders to the reservoir behind the baggage compartment. Mine was leaking at the front T. Any brake leak will find its way to the drain on the removable belly panel.
LANCECASPER Posted October 24 Report Posted October 24 There are some decent kits available to rebuild yours if that's where it's coming from: https://planepartsinc.com/store/mooney-m20j-m20m-brake-master-cylinder-kit/ https://www.gallagheraviationllc.com/Marsh-Brothers-Cleveland-Brake-Master-Cylinder-UpgradeRepair-Kit_p_329.html https://planepartsinc.com/store/880040-501-800029-501-mooney-m20j-m20l-m20m-parking-brake-valve-kit/
skykrawler Posted October 27 Report Posted October 27 I have replaced a leaking (steel braided) hose from the tee fitting to the input of the master cylinder. Amazing, virtually no pressure on that hose. Red fluid appeared again this year - deferred until annual. The right master cylinder seems to be leaking around the rod. The J models had several different parts numbers for master cylinders each with a different internal parts. My airplane as Cleveland 10-49 master cylinders - Lasar sells a kit, or you can just buy the o-rings. In the picture the small o-ring seals the shaft.
kortopates Posted November 2 Report Posted November 2 I have replaced a leaking (steel braided) hose from the tee fitting to the input of the master cylinder. Amazing, virtually no pressure on that hose. Red fluid appeared again this year - deferred until annual. The right master cylinder seems to be leaking around the rod. The J models had several different parts numbers for master cylinders each with a different internal parts. My airplane as Cleveland 10-49 master cylinders - Lasar sells a kit, or you can just buy the o-rings. In the picture the small o-ring seals the shaft. There isn’t ever any pressure until you depress the brake pedal - then there is a lot. The parking brake will hold the pressure for you but that’s further downstream after the master cylinder.For the OP, leaking brake fluid is never okay, and always a reason for further investigation to its source and state of available fluid. Sent from my iPhone using Tapatalk
skykrawler Posted November 3 Report Posted November 3 17 hours ago, kortopates said: There isn’t ever any pressure until you depress the brake pedal - then there is a lot. The parking brake will hold the pressure for you but that’s further downstream after the master cylinder. For the OP, leaking brake fluid is never okay, and always a reason for further investigation to its source and state of available fluid. Sent from my iPhone using Tapatalk HTG. So you must of missed the point that it was the hose feeding fluid from the reservoir - which is gravity fed. Also, in my case the 'gland' o ring which is against the rod is also on the low pressure reservoir feed end of business. In the process I discovered the stat-o-seal was missing in one of the masters. There were tool marks on the retaining collar so I assume it wasn't like that from the factory. I also replaced the o rings in the calipers which allowed a proper flush of all old fluid in the system. Also a good time to paint them.
kortopates Posted November 8 Report Posted November 8 On 11/3/2025 at 4:19 AM, skykrawler said: HTG. So you must of missed the point that it was the hose feeding fluid from the reservoir - which is gravity fed. Also, in my case the 'gland' o ring which is against the rod is also on the low pressure reservoir feed end of business. In the process I discovered the stat-o-seal was missing in one of the masters. There were tool marks on the retaining collar so I assume it wasn't like that from the factory. I also replaced the o rings in the calipers which allowed a proper flush of all old fluid in the system. Also a good time to paint them. Your right, I did miss that the hose in question was being fed by the reservoir since the reservoir wasn't mentioned. Nor is the airplane model or which brake your referring too is mentioned. It would be helpful to list your plane model under your name/avitar. But as an example, if you were referring to a right side co-pilot MC, the input lines are fed from from your left side pilot brake output. Context is helpful. But entirely agree on all else and good find on your part in finding the stat-o-seal was missing - hope its absence didn't damage the cylinder wall. As far as I know, that's only available buying parker's seal kit for the MC.
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