The Boat Guy: Wheel Drive Auto Pilot – Simple Maintenance Steps Make a Big Difference – Part 1
A Raymarine TS4000+ Autohelm wheel drive unit installed on wheel.
October 8, 2026
by Marc Robic
Whether you’re a sailor or a power boater, having a reliable autopilot available onboard is truly a great thing, providing you some opportunities to rest your arms and/or eat while under way whilst keeping an eye on things. So, when something doesn’t feel quite right, don’t wait. Executing some easy preventative maintenance on a regular basis is not only a cost saving measure but will give you back the confidence you once had in your auto pilot system. And doing so well before things start to break, as I’ve seen many times while researching this subject, is really both a great time and money saver.
My auto pilot is a Raymarine TS4000+ Autohelm with SeaTalk links. Although I have a sailboat, the same unit has been a very popular choice for power boats with a wheel type steering, such as large cruisers and trawlers so, this article definitely applies.
It had been a few years now that my autopilot (wheel) drive unit was making a swishing kind of noise when manually steering, which I always assumed was normal. Plus, the drive engage handle always seemed to get loose when not engaged. I had gotten into the habit of simply using an Allen key, which I kept readily on hand at the helm, to tighten the handle every once in a while, and simply accepted this as the reality of normal wear.
However, in the last few weeks, when the autopilot was engaged, it did not take much for it to get off course, especially under power, making constant erratic and noisy course corrections. When single hand sailing and performing an auto tack, it was also getting sluggish and unreliable.
So, with bad weather in the forecast for the next few days, I decided it was time to give the drive unit a little love and took the whole wheel home to take it apart and service it.
First things first, despite what some people may have told you, you really need to start by removing the whole unit off the wheel. I was told to simply grab the motor and pull. That the back half of the unit would simply pull/pop out. So, of course, I did and, to my horror, had most of the bearings fly out and ended up hunting them down on my hands and knees. Lesson learned!
Once I had the unit open however, the cause of the problem was very evident. One of the retaining plate screws was completing out and loose inside the drive unit (explaining the noise) and the other screw was so loose, it barely held the engage and tensioning cams properly centered in place in the retaining plate.
Blue arrows show the missing screw (left near finger) and the loose screw, preventing both the tension and engage cams from being properly centered into the retainer plate.
Another thing also stood out. The inside, including the ball bearing races were very dirty and dusty and in need of cleaning. So, in the end, popping the back cover off instead of removing the drive from the wheel and opening the drive properly, turned out to be a blessing as it forced me to take everything apart and self learn how to clean and reassemble the unit including reinstalling the intricate ball bearing races. I admit that took me a few minutes to figure out and thanked myself for taking pictures every step of the way.
Next issue in Part 2, Marc continues rebuilding the unit.
Marc Robic – The Boat Guy – Marc is a member of BoatCan who, with his wife, sails their Catalina 270, Aquaholic 3, out of the Ile-Perrot Yacht Club in Montreal, where Marc spent 16 years as Harbour Master. They are also regular Caribbean bareboat yacht charterers.
With over 40-years experience on boats, Marc is our OnBoard do-it-yourselfer.
