January 1, 2021
Happy New Year! My apologies in advance to those of you that follow my blog to read about our adventure. This post is a mechanical instructional. It is documentation of a solution we found to a common problem. My goal is to get it out to other folks that have the same problem. This blog is the best way I know to get it out on the magical interwebs.
When we bought our 1981 Skipperliner houseboat, it had shifting problems. A different problem on each side. In this post I will document how we fixed the problems.
For a few years Skipperliner used a DC motor to activate the shift plate. Most other years this function was achieved through cables rather than motors. Our boat has the DC motor set-up.
The system is designed so that the engine will kill for just a split second while shifting out of gear, and then immediately start right back up. We’ll call this “kill mode”. This allows the gears to come apart. Because of the design, the gears are able to go together while shifting into gear, but the engine needs to kill for a split second to allow them to come out of gear. On the Starboard side, the engine would “kill”sometimes when shifting into gear, or sometimes shifting out of gear, and not restart.
To complicate matters, sometimes it would remain in kill mode, which disabled the ignition making it impossible to restart the engine. As you can image, this can be a problem when docking or just maneuvering in general. This behavior can be observed on the tachometer as well. The RPMs will drop for a moment when shifting out of gear as seen in this video. (Yes, RPMs are higher than they should be in this video. Shifting RPMs should be around 600 or 700).
The port side developed the issue in which it would not always go into kill mode when shifting out of gear. This could also be observed on the tachometer in that the RPMs would fail to drop when shifting out of gear. RPMs would remain constant when they should have dropped for an instant. Another tell-tale symptom was an audible clunk when it should have been a smooth transition.
We learned that both the port and starboard shifting problems originated in the same place. The good news is that we didn’t need to search for any parts. They were simple micro switch adjustments. There are 4 micro switches per side for a total of 8 micro switches on a two-engine boat. Two are located within each shifting control box at the helm (if you have a fly-bridge, the shifter up top relies on the micro switches down below and does not have a set of its own), and two are in the engine compartment mounted on the shift plate.
Be sure to check that the micro switches are functioning using a multimeter. If they are functioning, you are in luck.
The micro switches get old and the arms stretch or bend causing the shifting problems described above. Adjustment to the micro switches in the rear is well documented on line. These microswitches in the rear are referred to as “shift interrupters.” A good instructional can be found here.
To make the adjustments to these micro switches Dave used our wireless security camera and set it up so that he could observe what was happening in the engine compartment while shifting up at the helm.
To solve our problems, the switches at the helm as well as switches in the engine compartment required adjustment, but start with the switches in the engine compartment.
To adjust the micro switches at the helm, first disassemble the shifter housing. After removing the cover, split the case in half by removing the long screws that hold the two pieces of the housing together.
The first switch is activated when the shifting cam moves over the switch arm. These parts are labeled in the image below. As the cam moves the arm in, it activates the switch. If a meter is used, one can determine, when shifting, if the switch is either bad or the arm needs adjusting. If the arm needs adjusting, it is a matter of trial and error. Usually, the arm needs to be bent towards the cam. The amount of bending will be slight. Don’t be too aggressive here. The second switch is not visible in this picture but its function is dependent upon the functionality of the first. Operating the shifter will show the expected position of the switches based upon the position of the cam and may or may not require adjustment.
Good luck. We hope we’ve saved you some money and headache. If you have any questions, leave them in the comments below and we’ll do our best to answer them.
Vintage, Electric Shift, Mercruiser, Skipperliner, houseboat, engine stalling, shift, micro switch,