Another Hynautic Steering Pump Question.

[Pete]

No doubt the answer to this question is somewhere on the Forum, but after 20 minutes of searching, no luck. So, excuse the duplicate if this is one.

The upper helm steering pump leaked a good quantity of cherry red low viscosity fluid under the helm and down the side of the cabin on my 48 LRC. No doubt there was a problem. So, relieved the system pressure, disconnected the lines, and removed the pump. It is a Hynautic H21S pump. The body is also stamped with 050776 which looks like the manufacture date, since I have a 0976 hull number. So, whats the problem. When compared to the parts explosion sheet from Hynautic I see two differences immediately. First, my unit has a 1/16 plate on the face of the pump held on with two "spring pins". Looks like this will have to come to get to the four nuts that hold the shaft end of the housing on, which is the second difference. The diagram shows no face 1/16 face plate, and the diagram shows machine screws holding the front housing instead of studs with nuts. A third difference is the diagram shows the last part going onto the steering shaft as a large nut, part number 11 if you have a copy. On my unit there is no nut. You see the end of a seal as the final part.

Any advice on how to proceed with a seal replacement would be appreciated, before I do something I will regret.

Pete

 

[MikeP]

If you do a search on "helm steering" you'll find lots of threads on the steering units.

Re the red fluid - it is probably either MIL 5606 (GOOD!) or ATF (Acceptable but NOT as good). It COULD also be a mix of diesel and ATF which some people have recommended as an acceptable substitute for the right stuff. Why anyone would do this is beyond me but there's no accounting for taste.

Basically the seal replacement is very easy and you have the option of using a couple of store-bought O-rings for maybe a buck or two, which folks have had good luck with, or buying the Hynautic seal kit for around 25 bucks.

The Hynuatic kit uses a "X" type seal which is superior to a regular Oring but it's probably not 25 times better! The other seals are normal o rings. It is not necessary to disassemble the pump to replace the leaking seals. In fact you should not attempt to do so unless the pump itself is damaged. This is extremely unlikely. They are very robust and unless water has gotten into the system causing rust/corrosion, there is almost no way it can fail. THe pump is a ball-bearing plunger type pump. If you take it apart it CAN be reassembled out of time so that it won't work. If you have two helm pumps, put new seals in both now. If one went, the other is soon to follow.

It's a good idea to drain/refill/bleed the entire system when you renistall the pump(s). Use MIL 5606 fluid, avialable on the internet or at any aviation supply store. It's much cheaper than "Hynautic steering fluid" and will provide smoother and lighter steering than ATF, which though approved for the system is not, per Hynautic, the best choice.

If you don't have them, Sams has the bleeding instructions on their site; click on Tips & Tricks and scroll down to it.