MerCruiser MCM 165 Trim Sender Wire

[brianadmans]

Hi Folks. I am hoping there are still some expert OLD MerCruiser experts out there with good memories!. I have a very old (79-81) MerCruiser MCM 165 - serial number 5653967 with what I believe is an MC-1 outdrive. I cannot seem to figure out which wire is the trim gauge sender wire (did this era even have a trim gauge?). Can one you please help. Thank you

 

[alldodge]

Welcome
When the trim sender first started it uses a Brown/White wire, and still does today

 

[brianadmans]

Welcome
When the trim sender first started it uses a Brown/White wire, and still does today

Thank you for this. I did have the correct wire it seems but I will have to figure out where it goes and why it is not producing the trim gauge results that I was hoping for

 

[alldodge]

The wire goes to the starboard side gimbal ring trim sender.

Look for the 4 black wires coming inside the boat from the top of the transom assembly. Two go to trim limit and the other two are go the sender. The black wires connect to other wires with bullet connectors

 

[brianadmans]

Please be patient with me!! On this boat (Mercruiser (serial number 5653967) with what I believe is a MC-1 outdrive. This outdrive does not have the 2 "pucks" that are normal. I am really not sure where the trim gauge sensor is or how it works but I might trace the brown/white wire back to see where it goes. anything you can share I would be very appreciative

 

[alldodge]

All good, will try and explain until you understand

Your drive does not have the senders mounted which means your drive does not have the capability for the trim gauge.

Even if you have a brown/white wire at the helm, the option for it can not be added without replacing the transom assembly and the drive.

 

[brianadmans]

Thanks very much. This makes sense

 

[kenny nunez]

Where the trim/limitwires come through the transom they are retained with 2 1/4”20 bolts which are almost impossible to unscrew without breaking off.
Also are very hard to even get to even with good tools. Just about every time I have tried to get to them one of them will break off. The only way they can be gotten to easy is with the gimbal ring removed.
The only other way is to re route the wires outside of the gimbal housing by drilling holes for the wires and running them through a hole in the transom.

 

[johnkom]

"...your drive does not have the capability for the trim gauge."

I have an MC-1 without the pucks and it has a trim sender and indicator. The sender is a small hydraulic cylinder in line with the up/down lines on the inside transom near the reverse lock out valve. And it still works.

 

[brianadmans]

I am going to take a pic of the back of the boat. It will show that I don't think I have that cylinder thing (I have seen that in another post). I wonder if it was an option OR whether someone ripped that out of this boat (which is totally possible too). It will take a few days for me to get that pic but I would appreciate any help

 

[theorifice]

I always thought it would be straightforward to splice in new senders to the existing wires so you wouldn't have to re-route through the transom. Why wouldn't this work?

 

[Scott06]

I always thought it would be straightforward to splice in new senders to the existing wires so you wouldn't have to re-route through the transom. Why wouldn't this work?

you can if the wires are in good shape. On mine they were brittle and corroded through

 

[Bondo]

I am going to take a pic of the back of the boat. It will show that I don't think I have that cylinder thing (I have seen that in another post). I wonder if it was an option OR whether someone ripped that out of this boat (which is totally possible too). It will take a few days for me to get that pic but I would appreciate any help

Ayuh,...... I've seen 2 different types of trim sensors on old MC-1s,....
There's the style like johnkom explains, which is mounted inside the hull, that works off the trim hyd. lines, in conjunction with the reverse lock valve,.....
And on the really old ones, there was sorta a lever thingy on the gimbel ring, that somehow could tell whether the drive was up, or down,.... only seen one once, 'n didn't look closely at it,....