1986 63MY. Vessel has Hynautic throttle and shift controls. Port side will leak from 80 psi to 0 in about
72 hours. Been doing this since I purchased 4 months ago. Works fine other than leak.
Fluid is not leaking anywhere and fill level has remained constant in reservoir canister, so assuming it
is an air leak at the top of the reservoir. I have replaced schraeder valve, added teflon tape to both
schraeder valve fittings. I am not able to remove pressure gauge without breaking reservoir from
ER bulkhead. No change. I have used soapy water twice on all fittings on top of canister. No bubbles
observed. Suggestions requested!
Is there something better than (dish detergent) soapy water to located a VERY slow leak? It seems to loose foaminess
quickly. I suppose my next
step is to remove canister, pressurize and submerge in bucket of water.
John McCarley
Water Colors
Wrightsville Beach NC
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Thread: Mystery Hynautic Air Leak
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08-27-2019 02:52 PM #1Senior Member
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- Apr 2005
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- 224
Mystery Hynautic Air Leak
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08-27-2019 03:51 PM #2
Re: Mystery Hynautic Air Leak
I had the same issue twice before, both times it was the gasket on the top of the reservoir, I guess they dry out as they don't get wet very often. They make a rebuild kit for those. It's not a big deal to DIY......Pat
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08-27-2019 07:32 PM #3Senior Member
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- Apr 2005
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- 224
Re: Mystery Hynautic Air Leak
Thanks. To clarify, are you referring to the o-ring at the fill cap or at the top of the round canister where
it meets the lid (top plate)?
John
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08-27-2019 07:43 PM #4
Re: Mystery Hynautic Air Leak
yessir!!
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08-27-2019 07:56 PM #5
Re: Mystery Hynautic Air Leak
Home Depot sells an all purpose leak detector, brand name "Oatey", claims to make "big bubbles for even the slowest leaks". Under $5 I'm sure there's others like it.
1978 53' Motor Yacht "LADY KAY V"
Hull number 524
Chesapeake Bay
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08-27-2019 11:56 PM #6
Re: Mystery Hynautic Air Leak
Airconditioning and refrigeration supply shops sell a liquid product called microleak detector. Comes in a spray bottle.
+++
1984 61MY #353 with 9' cockpit extension.
Sydney, Australia.
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09-03-2019 08:27 AM #7Senior Member
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- Apr 2005
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- 224
Re: Mystery Hynautic Air Leak
Used the leak detector and nothing found. Cannot really test gauge with leak detector without tearing gauge apart. Will replace gauge and try test again. After that, I'll rebuild the canister unit. Having to defer work until we get through Dorian.
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09-03-2019 08:51 AM #8
Re: Mystery Hynautic Air Leak
Ensure you put pressure back in the system. I've used dish soap and look for bubbles
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09-04-2019 01:36 PM #9Senior Member
- Join Date
- Apr 2005
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Re: Mystery Hynautic Air Leak
Have pressurized to 80psi and searched with dishwashing liquid/water 3 times. No Joy! Now, when I
re-pressurize the throttle (both helms) is spongy feeling; moves forward but returns to idle position. I think Ill call technical
support.
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Re: Mystery Hynautic Air Leak
Don't want to be the bearer of bad news but Hynautic has been out of business for quite a while so tec support is hard to come bye.
Best place I found for all hydraulic repairs is in Florida http://www.boatsteer.com/
These people are the nicest and fastest service for Hynautic steering and shift problems and stock tons of parts. If they don't have the parts they can make them. Suggest calling them for advice on where to look first.