Autohelm ST7000

[markpj23]

The hydraulic pump on my ST7000 is not working. I get voltage to it, but it sounds as if a gear drive internal to the unit is stripped... makes noise but no pressure output.

All the manuals I've found for the ST7000 address the control heads & other electrical / electronic components. My guess is that the system works with a variety of hydraulic / linear drives, so my installation is unique - as would be others.

Picture of my unit:
http://cruisersforum.com/photopost/d...st7000-med.JPG
Has anyone on this forum dealt with the same setup?

[Rick]

If you haven't already done so make sure that there is no air in the pump, that is the first and easiest check to make.

If you are mechanically adept you can disassemble the internal valves to discover if dirt has contaminated them (or any other part of the pumpset). So, cleaning and purging is the cheapest first thing that you can do before taking the entire thing away to have it serviced. If you are able to do it yourself you can identify the bearings and seals to buy them yourself from a bearing mart in your area. Otherwise you will pay many times the cost from the dealor. Most bearings and seals of that sized unit are only a few dollars apiece if universally available from a bearing mart.

Your PWM (pulse-width-modulated) drive unit operating with a small heading error delivers a "growling" noise that gets bad sounding if the valves are leaking and there is air in the pumpset and I wonder if that is the sound that you are hearing.

[delmarrey]

I concur with Rick.

Air will make pumps grawl. Actully, air can damage pumps. They cavitate and eat away the internal parts. Check the oil level and bleed out any air, if it has bleeders. You might even want to do an oil change. Moisture gets in there and can rust up parts or pit the bearings.

I work with hydrulics almost daily and it can be a blessing or a burden but is EZ to remedy..........................._/)

[Alan Wheeler]

These pumps are called a"positive displacement pump". Rick is quite right in his comments and so firstly follow his advice on checking for air. The valves are a little more difficult in this design. As you will have noticed, the pump and ram are part and parcel in this set up, and a little less than as straight forward as just a simple pump. However, the basic operation is the same on all of them. Just where the components are situated may differ.
First of all (assuming you have checked for Air first) if you have to strip it down, I suggest trying to get a parts break down.This will enaid you in knowing where springs, valves and seats are. Most of these pumps have little valves that use a ball bearing and a spring. There is nothing worse than to undo a cap and have a ballbearing and spring shoot over your right shoulder
As for how it all operates. The electric motor is the only part seperate to the pump itself. It is unlikely, but the drive at this point could have failed. The internals are a plate that is on an angle and oscillates as it rotates push the little pistons in and out. The pistons are nothing more than a hardened metal. They don't usually have any seals as such (although don't rule that out) and it is vertually impossible for them to fail. It is possible to have that yoke plate/piston to fail, but very rare.
Good luck and continue to ask questions if you need.

[DeepFrz]

Mark, how did you make out with your noisy hydraulic pump?

Phil

[markpj23]

Other priorities got in the way. I hope to tear this one down by the end of the month. (not committing to which month here...)

Benefit of manual steering is that you really learn how she handles...

[S/V Elusive]

As an aside - Mark? How DOES your E52 handle? Is it ketch rigged? I have been using the ST6000 series in mine and it has done well. Only regret is that I didn't get the upgraded 'brain' (not mine, the autopilot). The boat had the 6000 series installed, but (of course) it didn't work so had to replace the computer, sensors, and control head(s) - the drive unit was fine, and worked with the new system.

[Talbot]

if you have the upgraded brain fitted, it may be possible to get the rate gyro added as an extra. worth contacting raymarine to investigate, as it makes a big difference.

[GordMay]

Maggie wants to know where I could get an “upgraded brain” fitted, how much the surgery costs, and how long my post-surgical recovery might take?

[Talbot]

LOL!

[markpj23]

Well today I bled the hydraulic ram and found no air lock or bubbles. The brain tries to drive the rudder but the darn pump sounds like there's a broken gear inside it or something. I'm afraid this one will take lots more time to resolve

First to remove the ram from the quadrant - gee that should be fun...

[DeepFrz]

Hi Mark, I was just wondering if you ever got your autopilot fixed?

[markpj23]

Originally Posted by DeepFrz

Hi Mark, I was just wondering if you ever got your autopilot fixed?

Not yet unfortunately... 3 head rebuilds (on a 2-head boat no less) and a FWD A/C replacement have consumed my time thus far. And we actually plan to go SAILING for the next 2 days!!

I hope to get this autopilot ripped out saturday morning and take it home with me for repair. But I'll be darned if we didn't just discover that the genset exhaust hose has rotted through near the outlet fitting and is leaking fumes into the boat.... sigh....

[markpj23]

Well.... mystery solved! I pulled the whole ram assembly, took the hydraulic vane pump cover off - no issues seen at all. Hmmm......

So off to a local hydraulics repair shop. Turns out the issue was electrical.... one of the motor brush springs had broken and there was arcing across the brush. A quickly fabricated replacement and armature clean-up had me back up in no time.

Since I'm less comfortable with hydraulics than I am with electrical.... I of course assumed the worst and started checking hydraulics first.

Will be a much nicer transit to FL now that we won't be hand-steering the whole way.

[yachtsman44]

I am having what seems to be the worst kind of problem......intermittent failure.

Yesterday I activated the autopilot and as soon as it made its first correction it never came out of the turn.....

After several tries it kept doing the same thing. Heading indicated 113 and activating the AUTO button it turned the rudder to get back on course, but never came out of the rudder change.

After a few hours, still on the same general heading, the heading indicator showed 130, so I tried the AUTO button again and.....it worked and kept on working fine for the rest of the day.

It almost seems like something in the electronic heading sensor got stuck, but as far as I know, the heading sensor has no moving parts.

I welcome comments form experienced users that might be able to suggest a solution for me, as I will be no place that I can get competent service for the next few months, and I dread the idea of manual steering on long passages. If necessary, I can get replacement parts by FedEx.

Thanx for the prompt support.