Hynautic 50 upper helm feels off - crunchy for lack of a better term

[denders]

Hi all - We have a Hynautic 50 helm on our 1985 3607. The upper helm was feeling off , the movement wasn't smooth more of a crunch every couple of degrees. The marina topped off the hydraulic fluid and made sure the air pressure was correct. This didn't fix the issue so we had them swap the lower helm pump with the upper. My question to the group is - would a rebuild help or if not what would be a replacement since they are not made anymore ?

Thanks in advance

[Viper]

Some parts for the Hynautic are still available.

To replace the pump with a new one, you'll need Seastar:
1x HH5273-3 - 2.0 Cu.In Displacement - 3/4" Taper Shaft Helm
1x HA5418 - Back Mount Kit
1x HA5432 - Non-vent plug
3x HF6012 - -5 ORB Male x 1/4" Female NPT

You can get these individually through various retailers or you can go here, they sell it as a kit: https://www.seatechmarineproducts.com/hynautic-h-50-hydraulic-helm-pump-seastar-replacement-kit.html

[denders]

Thanks Viper - Replacement may be better than a rebuild , I have no idea what would cause the feeling we were getting.

[Viper]

Give Seastar a call to confirm the model above is the one you need to replace your Hynautic model but I suspect it's correct. I'm just not used to seeing a 2.0 cu. in. unit on this size vessel.

Dismantling the unit isn't that hard to do, there's several YouTube videos on it. Do that first if you're handy, it may just have a lot of crud in there, and a seal kit is about $50 compared to $1000 for a new pump retrofit. There's still a lot of parts available for the Hynautic should it be a part that needs replacing. You could also hunt down a used unit from a boat salvage yard. Relieve the air pressure in the reservoir before disconnecting the lines to the helm. By the way, the fluid should be inspected, and replaced if needed. If the grinding is the result of worn metal components and there's metal particles in the oil as a result, it'll eventually ruin the other helm and the steering cylinder.

[km1125]

Is it possible you just need to bleed the system? After many years of running fine, I started noticing a noise one year on the bridge. You could also feel pulses as you cranked the wheel around. Still worked fine but was annoying. Found out how to bleed the system (loosen check valves on cylinder at stern, then crank wheel both direction PAST the stops). It also helps to LOWER the pressure in the reservoir when doing this, as the entrapped air bubbles get BIGGER and easier to pump through the system. Then tighten the check valves and repressurize the reservoir and you're all done. Worked like a charm.

I had to do that twice over ~20 years. I was expecting to have to replace the seals but they never leaked. That is not that hard of a job to do and you can get the seals from any good hydraulic shop. I think I posted the parts on here in a different thread.

[Viper]

I agree with km, consider other possibilities before you dismantle or replace. One would hope though that the marina checked all that first, and since the swap of the helms resulted in proper operation at that station again, one would think it's indeed a helm problem.

[Cooler]

There is a system available that bleeds these systems very easily. Connects to both ends at the same time, and bleeds by circulating the fluid. Most likely a mechanic in your area would have one, and the job will take 10 min., instead of 2 people working for an hour, or more. If you have no leaks, it really sounds like air bubbles. Look real close at the steering arm at the rudders. They can start with real small leaks, and eventually get enough air to blow the seals in the helm pump. Good luck! er