Autohelm 4000 bad failure mode

[rxc]

About 4 weeks ago I experienced a very bad failure involving my Autohelm 4000 autopilot, and I thought I would share it with several different lists where these autopilots are common, so that other people can recognize this problem when it occurs.

We were sailing along(music, please) with the autopilot engaged, in lively winds (10-15kts), close hauled up the bay.  All was going well, till I noticed that the wheel was not responding well to wind shifts.  Watching the autopilot, it became apparent that although the motor was turning, the wheel was not consistently moving.  I reached down to disengage the pilot, and when I flipped the lever, it did not disengage.  I could not disengage the autopilot, and I could not steer with the wheel (except with extreme force applied to overcome the motor drive train gearing.)

Thinking that this problem involved the belt drive mechanism, I popped the unit open, and out camethe belt - in fine shape, and the autopilot disengaged from the wheel.  I then proceeded to hand steer for the rest of the day, with the various parts of the autopilot drive wheel hanging off of the shaft of the wheel, in pieces.

When I got back, and all was taken apart, I discovered an eccentric-mounted wheel attached to the small lever.  When you flip the lever, it forces the eccentric wheel against the belt and against another, separate idler wheel, thereby engaging the belt and the autopilot.  The eccentric wheel is attached to a shaft, which is attached to the lever, with two small roll pins, which had sheared.  When they shear, the lever is not connected to the eccentric wheel any more, and it will not move from its last position.

I called Raymarine, and they sent me a complete lever assembly, with a new lever, shaft, eccentric wheel, and roll pin for the lever.  Installed in a few minutes, and back in service.

This is not a good failure mode for an autopilot, and those of you who have a 4000 should understand it, and how to deal with it, because I think it may not be an uncommon failure, either.  The fact that Raymarine sells a replacement kit for this lever tells me that they have seen this failure before.

So, if you do have a 4000, please be aware that you may have to stick a screwdriver into that slot sometime, and twist it to get the belt drive to fall apart in you lap, in order to regain steering.

Other than this bit of excitement, I do love the unit.

Ralph Caruso
s/v "On y va"  C34#777 Ches.Bay/Magothy

[Norris Johnson]

This happened to a friend of mine who owned a 36 Catalina. He had the same AP. he never knew what failed because he let someone else fix it. Glad to hear you investigated your problem. Do you feel this won't happen again? How old was your unit? Guess I'll have to keep a screwdriver handy. Thanks N

[rxc]

I installed the unit in the fall of 1995, and it had worked well since then.  The only problem I had seen previously was that the unit occasionally popped out of gear when the boat was hard on the wind.  I think that may have been an early indication that one of the two roll pins that hold the eccentric wheel in place may have either sheared, or deformed enough to throw off its engagement a bit.  I will watch for that behavior in the future, and inspect it if it happens again.  It was good to see, though, that the belt was still in fine shape.  I have heard about people wearing out the belts on these units, but ours looks like it is good for 10 more years.

Ralph Caruso
s/v "On y va"  C34#777 Ches.Bay/Magothy

[jentine]

I carry a spare set of rolled pins for the lever.  I have had this unpleasant experience on two occasions.  Raymarine sells the SS rolled pins without all the other hardware for a mere fraction of the cost of the assembly.
Jim Kane

[rxc]

Jim,

Can you share with us the Raymarine part number for the roll pins?  When I called, they told me that they only sold the entire lever assembly.  I still have the old parts, and would re-build them them if I could get the pins.

Ralph Caruso
s/v "On y va"  C34#777 Ches.Bay/Magothy

[jentine]

I will see if I can find it.
Jim

[Denny Dutcher]

you are so correct.  I have lived aboard for the last two years and have had the same part fail 3 times.  Boo to Raymarine.  The order person is not very charming either since you must have part #'s to order.  Ask to transfer to tech support for the #'s and then back to the order girl.
Denny aboard Turning Point

[rdavison]

Yup, I read this thread just before leaving on a week's vacation only to have it happen yesterday!  I pieced it back together with a cotter pin.  Has anyone come up with the part number for the pin only or a suitable substitute part.  The shear force on the pin is considerable.  I'm thinking of using a small drill bit cut to length if the cotter pin shears - this to get through the vacation.

Randy Davison  k7voe

[Ken Juul]

Ace Hardware, Lowes, Home Depot usually have a great selection of roll pins.  If you have enough of the old to match might want to go browsing.

[rdavison]

Ken and/or Vicki:

Thanks for the suggestion.  I'll try Lowes and Home Depot for roll pins.

The drill bit held in place with electrical tape worked fine to get home.  Nothing else I tried had enough shear strength to hold up.  After watching every other form of pin or wire I could think of shear right off, I agree that the design appears pretty marginal.

Randy Davison  k7voe

[rdavison]

Additional info for the group.  The roll pins are multiwrap type with about 2 full turns of stainless.  The only ones I could find at Lowe's were a single layer.  I'm sure they wouldn't hold up to the shear.

I found them at "The Offshore Store" in Seattle for a buck apiece.  These folks are dealers and repair for Raymarine.

Randy Davison  k7voe

[PLKennedy]

Last year twice, and this year once, whilst on autopilot, "Snow Goose" did a 360, until I stopped her.  Needless, very disconcerting.

The problem was a defective fluxgate compass, which I just had replaced.

I expect to have a lively conversation with Ray Marine, since the two year warranty expired in June.  I'm certain that Ray Marine will not have logged my first complaint over the phone, made within the warranty period.

Peter

[Ken Heyman]

This happened to me (us) yesterday. We were snakeing thru traffic that was competing for position to watch the aerial performance practice for the Chicago Air And a Water Show. As we approached the anchored boat field (under power) I disengaged the autopilot to steer manually. ---Nada-- the wheel,wouldn't budge so I checked to make sure that I had disengaged the lever. I had ,but the wheel was locked. After a bout of "that sinking feeling", I realized that I could turn the wheel, albeit with much effort. What did work efficiently however and got us out of a potential jam was continuing to use the autopilot as the primary steering device. We steamed away from the other boats and anchored. I had previously (probably close to 10 years ago)bought the pins that are often responsible for this kind of failure (per discussion on this forum).
I decided not to attempt the repair while we were anchored but instead removed the autohelm from the steering wheel. (Fortunately I had the correct Allen wrench) At this point I'm not sure how much damage there is other than the sheered pins but I suspect I should replace some of the rollers and components ,that I briefly inspected.
Any additional advice would be much appreciated.
Thanks in advance,
Ken

[Ken Juul]

Another option is to use a drill to enlarge the holes for the roll pins and use a small stainless bolt with a locking nut in place of the roll pin.  Much stronger and less prone to corrosion.

[Ken Heyman]

Thanks Ken,
here is a step-by-step I found on Cruisersforum. it's probably on ours somewhere as well.

http://www.cruisersforum.com/forums/f13/how-to-repair-an-autohelm-st4000-z326-wheel-autopilot-mk-i-109239.html

and here's another one:  http://c34.org/bbs/index.php/topic,8623.0.html  [Stu]