Tilt and trim senders

[Levithan]

Hey guys
I have a few questions on my trim limit and trim gauge senders.
I just recently replaced my fresh water hose, checked the bellows, engine alignment and reinstalled my outdrive.
Figured I would disassemble clean/grease the trim limit and gauge senders while I was there.
Good thing I did as I found quite a bit of rust in the contacts.
Anyhow here is where my questions come in.
The inside of my trim limit switch looks like 1 copper contact on either side of a circle with the center piece being a smaller circle with a contact bridge in the middle.
I cleaned and lubed everything and it appears to be operating correctly I think.
Is this switch just designed to stop the trim motor from raising the drive to high, or is it also supposed to stop the trim motor from trying to go down past it's limit(my trim motor won't automatically shut down when at the end of downward travel, normal)?
Next is my gauge sender which on the inside looks like,two raised silver contacts on either side of a circle and an upper disc with an almost half moon silver contact on one side and a silver at the top and bottom black in the middle almost half moon on the other.
My trim gauge either reads full down or full up(depending on drive position) but never anywhere else on the gauge.
Is this normal?
Possibly that is the style of gauge I have or is this the style of sender I have?
Are there even different alpha 1 gen 1 gauge senders?
I would just like to know what position my drive is in at all times not just full up or down.
I don't use the gauge for planeing, would just like to know for depth reasons in shallow waters.
89 3.0L mercruiser with Alpha 1 gen 1 drive.

 

[tazrig]

Re: Tilt and trim senders

The trim limit switch is designed to limit how far UP the drive will go and still allow you to safely operate the engine. When the drive reaches the full down position the pump will continue to pump (this is normal) but you will hear a distinct difference in the sound as if it is straining. (the rpm of the pump will drop way down, also normal) Same thing when you raise your drive all the way up for trailoring. On your gauge sender, although Mercruiser has made some improvements in their design on the newer Alphas your era sender is notorious for giving inaccurate and inconsistent readings. You can adjust it or even replace it and have the same problem 1 hour later. The only way to get a "true" reading each time of where your drive is at is to get a set of manual indicators like these:

http://www.livorsi.com/catalog/mi.htm

There are other manufactures, I just happen to pick Livorsi as they are one of the best. Anyway you would need to run a cable similar to a throttle cable from your dash where you would have the display mounted back to your trim piston. When you raise or lower your engine up or down an inch it shows an inch worth of movement on the indicator each time, consistently. That is the only way to get the same truly accurate reading each time.

 

[achris]

Re: Tilt and trim senders

I agree with the comment about the problems with the earlier trim senders, but the latest supercession seem to work well and last quite a while. I operate in salt and the units on my boat are now 6 + years old. The previous engine's senders are 19 years old and still working. Quite reliable and consistent. Part number for the kit (and you can only buy them as a kit with both sides in) -805320A1.

You might want to try turning the centre of the trim sender (gauge sender) with it of the gimbal ring and see if it's actually in the right place.

Chris......

 

[Levithan]

Re: Tilt and trim senders

Thanks for the replies.
Ok so then my limit sender is working correctly, I just need to set it at 21 3/4 for the rams as per the manual(will do that tonight).
On the gauge sender, it is not only inaccurate, it just plainly doesn't work right.
I get full down only on the gauge when the drive is down, as the drive raises about 1/2" all of a sudden the gauge goes full up(no gradual rising just an instant swing to full up.
Is it possible my gauge is buggered and will not read the different ohm readings or maybe normal for this gauge?
Or is there just an up/down sender from merc without variable resistance?
Has anyone had there senders apart to confirm what mine look like?

 

[dubs283]

Re: Tilt and trim senders

On the gauge sender, it is not only inaccurate, it just plainly doesn't work right.

have you tested the guage?? - they rarely go out

if the sender is giving you trouble and the guage checks out fine, just replace the senders - merc does NOT recommend splicing any wires or disassembling the senders to repair them, they are strictly a remove and replace item

merc designs the analog senders to read correctly in the full down position - that is the most important position to know, yes the guage will show the drive trimming up but its kinda arbitrary as smoe guages read differently than others, boat manufacturers dont all use the same guages

 

[tazrig]

Re: Tilt and trim senders

Thanks for the replies.
Ok so then my limit sender is working correctly, I just need to set it at 21 3/4 for the rams as per the manual(will do that tonight).
On the gauge sender, it is not only inaccurate, it just plainly doesn't work right.
I get full down only on the gauge when the drive is down, as the drive raises about 1/2" all of a sudden the gauge goes full up(no gradual rising just an instant swing to full up.
Is it possible my gauge is buggered and will not read the different ohm readings or maybe normal for this gauge?
Or is there just an up/down sender from merc without variable resistance?
Has anyone had there senders apart to confirm what mine look like?

Yes, your limit sender is working correctly. With the old style gauge sender there isn't much you can do. I don't know of a single person who had them where they worked any differently from just what you are describing. It's almost irrelevant whether or not your actual gauge is gone because even assuming you put in a brand new one that you knew read the correct ohm range and worked perfectly your sender would still be sending it bad information and cause it to read incorrectly. There are only 2 styles of electronic trim senders for your drive that I know of. The ones original to the drive and the improved ones they make now. Both look the same from the outside, small discs. The updated ones are reported to be much better as achris stated and may well meet your needs. If you need or want exact measurements than you would need to switch to a manual system that runs a physical, non electric cable from your trim cylinders like the one from Livorsi or like manufacturer.