Hello.. This is a pretty long post so here goes:The Trim Senders are located on either side of the Gimbal Ring.The Trim Limit Switch is mounted to the Port side of the Gimbal Ring. Newer model switches will have a "TL" or "Trim Limit" embossed in the plastic The Trim Sender Switch is on the Starboard side of the Gimbal Ring.The newer model Trim Sender switches have a "TP' or "Trim Position" embossed in the plastic. Each switch has a wire harness that is routed behind the Bell Housing after which it passes through a small hole in the Gimbal Housing shroud and into the bilge.The wires look like black lamp chords. It is these wires and how they are installed which makes replacement of the switches difficult. Partial disassembly of the Gimbal Housing is required to replace the switches and wires. You must always replace the wires with the switches. Never just replace the switch. The wires absorb water which leaks up the core of the wire to the switch. If you simply replace the switch it will not work or it will go bad in just a short while.The switches are sold in a Trim Limit/ Trim Sender Switch Kit which includes both switches.The wires are included in the Kit and they are soldered and sealed in place at the factory.You can not buy just one switch. You can only buy the pair of switches in the Kit.
Replacing the switches is no easy task. Mercruiser customers will need a Hinge Pin tool. Tilt the drive up and remove the clamp from the rear end of the exhaust bellows.Pull the exhaust bellows off of the Bell Housing.NOTE: Installation of the exhaust bellows requires the use of a special tool.Sometimes old exhaust bellows can be reinstalled without the tool. If the bellows can not be fitted back into place, you will need a Bellows Expansion Tool.You can also buy an Exhaust Cuff/Tube and install it in place of Exhaust Bellows.The Exhaust Cuff/Tube does not require the Expander Tool.Turn the steering to one side so you can access the switch retainer screws.Take a phillips head screwdriver and remove the two retainer screws from the first switch.Pull the switch away from the Gimbal Ring and tie it up out of the way.If you don't tie the switch up out of the way it will get caught between the shroud and the gimbal ring when you try to turn the steering to the other side.Use your Hinge Pin Tool and remove the threaded hinge pin.Turn the steering to the other side and remove the other switch.Remove the second Hinge Pin.
Use a 5/16" swivel socket (1/4" drive) on the end of a very long extensionand loosen the Ujoint Bellows Clamps at both ends of the Ujoint Bellows.The Bellows are glued into place with Bellows Adhesive so it will take some force to pull them freewhile you separate the bellows from the housings using a dull screwdriver to break the seal. NOTE: This is a great time to replace your Ujoint Bellows.If you think that you might have damaged the ujoint bellows during removal, replace them.Never install damaged ujoint bellows.You should now be able to pull the Bell Housing far enough away to loosen the rear water hose clamp.Careful..... twisting and maneuvering the Bell Housing can ruin the delicate shift cable.We recommend replacing the shift cable whenever this type of repair is being done.
You will now be able to see where the trim wires go.There is a small retainer plate holding and sealing the trim wires in place as they pass into the boat.This plate is held in place with either one or two small bolts.NOTE: These screws might be corroded in place. Use patience and take your time removing the screwsbeing careful not to snap them off.After both screws are removed you can remove the retainer plate and set it aside.Hop up into the boat and locate the wires inside the bilge.Make a note as to how the wires are routed and hooked up.Disconnect the wires and pull them out from behind the boat.Installing the new senders is the reverse of removal.Goo the threads of the retainer bolt(s) with Perfect Seal so they come out easy next time.The new trim wires will have grommets molded onto the wires.When you route the new wires through the hole take notice of how the sealing grommets fit.Tie both switches up high and out of the way during assembly of the Bell Housing or they will get cracked.If you have decided to replace the Shift Cable, do that first.After the Shift Cable is installed go ahead and install the water hose.Pushing a new water hose on to the tru-gimbal-fitting can be very difficult and frustrating.We like to coat the inside of the hose with Mercury Power Tune spray or grease.Make sure the clamp is loose but in place on the hose before pushing the hose onto the fitting.Push and twist and push and twist and then push and twist a little more.It has to go on far enough. If not, it will pop off and you will overheat the engine.Snug up the clamp and then clamp the other end of the hose on the brass fitting in the Bell Housing.The position of the water hose clamps is important. They must be positioned as so you can access the screw.Now it's time to glue your u-joint bellows in place.Do NOT install the bellows without bellows adhesive!It's important to note how the clamps will be positionedThe bellows will first be installed on the bellhousing. The clamp will face down opposite the side with the water hose.When we install the bellhousing to the gimbal housing (transom) we will have to have the clamp positionedwith the screw facing down on the stb. side.Now.... note that the bellows has a "Forward" and "up" at one end.This means the obvious!Coat the "rear" end of the bellows (inside) with bellows adhesive and before the glue dries, push the bellows onto the bellhousing.It should almost "snap" in place when the grooves line up.Make SURE that they are straight BEFORE the glue dries!Now, position the clamp and gently snug up to tighten.The next step will be to coat the other end with bellows adhesive and place the clamp loosely on the bellows.Make sure the clamp is positioned with the screw facing down on the right!Push the entire bellhousing assembly up and into place while feeding the the shift cable back through its bellows.You will have to be feeling inside the hole to assist the bellows into place.Also, you will have to push the bellhousing WAY IN to "snap" the bellows onto the groove.While this is taking place, you also have to watch that the clamp has not fallen out of place!Once you feel that the bellows are fully in place, hold it there for 5 minutes to let the glue set-up.Now take your 1/4" ratchet set with a long long extension and a swivel 5/16" socket on the end and snug up the clamp.Inspect carefully to make SURE the clamp is straight and in place.DON'T over tighten the clamp!!Now that both clamps are snug, you can get the hinge pins installed.There should be fiber side washers on either side between the bellhousing and the gimbal ring.If they look worn, replace them.Align the washers and the bellhousing up.Apply a drop of good lock-tight to the hinge pin threads and install the pins.Torque the hinge pins to 40 lbs.Usually the Trim Sender Kits include some basic instructions.Before fitting the switches into position on the hinge pins, take a look at the them.The center piece rotates. You will see a notch on both the center piece and the housing.These notches are alignment marks.Turn the center piece as so the alignment marks are lined up.With the drive in the FULL DOWN position you will install the switches being careful not to misalign the marks.Most of the time this will be the perfect position and the Trim Limit and the Trim Gauge will be right on.Some minute adjustments may be required to "tweak" the gauge reading and trim limit setting.Your Shop Manual will describe the exact height for the Trim Limit.Loosening the retainer screws and rotating the switch housing just a little bit in one direction or the other will change the settings. Snug up the screws and cycle the drive up and down to confirm your setting.You will adjust the senders after the drive is mounted.Grease the hinge pin zirt fittings.Now it's time to inspect your work.Look at the clamps again, are they perfect?Did the bellows seat completely>Is the water hose kinked?If you didn't cut the water hose OR if you didn't get it ALL the way on, then it will kink.It's simple to fix, just redo everything again.We still have to contend with the exhaust bellows.This is where you get to use your new exhaust bellows expansion tool!This tool will pay for itself with just ONE use.Clamp the exhaust bellows first to the gimbal housing (transom).You really don't need adhesive for the exhaust.The clamp should be on the bottom if possible.Now place the other clamp on the rear end and get them position CLOSE to the installed position.Work the bellows expansion tool in through the bellhousings exhaust passage and into the bellows.Expand the tool and place the lock in place.Pull on the tool to work the bellows up onto the bellhousing.Now, slide the metal rod pin through the hole in the tool. This allows you to release the tool so you cantilt the bellhousing up to access the last clamp.Hey! your practically done!Finish up by properly installing the drive and go boating.