Hynautic Reservoir Air Leak

[JLR]

I am trying to find a temperature sensitive air leak on my hynautic reservoir that serves the hydraulic controls on my 56 MY. Ever since I have owned the boat, when the temperature drops in the winter, my normal operating pressure of between 75-80 PSI drops to about 30-40 PSI. I am losing no fluid so I know the leak is in/around the reservoir. It must be a very slow leak because spraying the reservoir with soapy water does not show it. I have already replaced the warning switch plumbed into the reservoir and the shraeder valve but they were not the the problem. Short of replacing the entire reservoir, any ideas? In the warmer months, there is virtually no loss of pressure.Also, if I do have to replace the reservoir, am I correct that I will not need to bleed the system for air?

[mikep996]

20-30 PSI is the proper pressure according to the hynautic steering manual for our 1980 53MY. Are you sure that 75-80 psi is correct? Sounds awfully high for reservoir pressure.

Per hynautic instructions you DO have to bleed the system if you replace the reservoir or hoses, or any portion of the system. Quote (the comment in brackets is mine): "If a line must be disconnected [which it will to remove the reservoir] , exhaust the air pressure from within the reservoir and remove the filler plug. Then open the relief valve screws to relieve all pressure in the lines. After work is completed, reconnect lines and repurge the system of air."

[mikep996]

I ASSUMED you were referring to the steering. But it occurs to me now that you didn't say that. if you are talking about other hynautic controls - my answer does not apply. I have no idea of the proper pressure for anything other than the steering reservoir. Throttle and tranny controls are probably much higher. I also do not know about the reservoir replacement/bleeding for that application.

Sad, :( if I misunderstood your question! Happy, :) if I did not!

[surfdancer45]

Did you check the schrader valve where you pump in the air? These can go bad over time. Bob

[JLR]

I was talking about the throttle/clutch pressures, not the steering pressure. I have checked the shraeder valve. That did not seem to be the culprit.

[Trojan]

I don't know your system, but from the way you scantly describe it. It's a hydraulic oil CLOSED loop system. You didn't describe the system enough. It sounds like a temperature problem and not a leak. It sounds more like a temperature controlled oil viscosity problem. In small lines and cold temps the fluid does not want to move as easily and your static pressure could be low. Somewhat like a flow control. You didn't say where the pressure was being measure. In a closed loop system movement is usually one for one. I would think that the movement would also be slowed and maybe stiff. Any closed loop system must be bled (to remove air, Like car brakes) after a line has been disconnected. I would check to see if I had the correct hydraulic fluid in the system. It sounds like the wrong fluid. I'm not sure what you are doing with the air in the hydraulic reservoir. Maybe you can give us a little more info. Bill

[oldhatt]

be careful here. i think there is a label on the reservoir indicating what fluid to use. i just worked on one of these units and i think the fluid is a 50-50 solution of. ethylene glycol and distilled water. if you need further info i may be able to get my hands on a manual. hynautic part #MCO-03.
safe boating:D
sam

[Salty Dame]

instructions are available online at the teleflex,hynautic web site. Its best to have a helper with you or a lot of patience. Make sure the slave linkage is unhooked at the engine to allow full movement during bleeding. It took a long time to get mine right but they sure work nice now.

[jlr]

Spoke to Hynautic. They said leave it alone. It results from the shrinkage of some metal (aluminum) tubing inside the reservoir based solely on temperature. They also said that I could easily run the system with 0 PSI so the drop I am talking about during winter months when layed up is of no concern. They did not recommend replacing the reservoir or doing anything else. They also said that the ratio of antifreeze to water could be different between that reservoir in my port engine room and the ratio in the starboard engine room that has no pressure drop.

[rufuschamblee]

here is another source of parts and information. They are much more responsive than Teleflex. www.charment.com/ (http://www.charment.com/)