old merc three button tilt/trim help

R

rcb130

Petty Officer 1st Class
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Sep 28, 2005
Messages
221
I have a 1974 merc 850 with the two cylinder tilt/trim with three actuating buttons. Can anyone tell me how the buttons are to work? It seems that sometimes the middle and "up" button need to be pressed at the same time. Any help would be greatly appreciated.
Thanks
 
L

Laddies

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Joined
Sep 10, 2004
Messages
12,218
Re: old merc three button tilt/trim help

If the tilt and trim buttons must both be pushed to trim, then the trim switch on the port cyl. is bad. if the engine is past the trim position then you must use both buttons.
 
R

rcb130

Petty Officer 1st Class
Joined
Sep 28, 2005
Messages
221
Re: old merc three button tilt/trim help

If that is the case why is the middle button marked "up" on the top half of the switch and "in" on the lower half? I still do not understand how this switch was designed to work.
 
merc850

merc850

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Jul 7, 2010
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2,026
Re: old merc three button tilt/trim help

Then "IN" button trims the motor in, the middle button trims the motor to a preset stop you set with the limit swich, you press the middle and "UP" button together to raise the motor for slow shallow running, beaching or trailering.
The limit switch should be located on the PORT trim cylinder.
To set the limit switch you start with motor trimmed all the way in. then accelerate to full throtle and trim the motor out until it starts to overrev.Trim motor in until it stops overreving and adjust the limit switch.
 
C

Chris1956

Supreme Mariner
Joined
Mar 25, 2004
Messages
27,137
Re: old merc three button tilt/trim help

To add to what merc850 said, the trim limit switches fail all the time in the open position. Then only the middle and top buttons will trim/tilt the motor when pushed together. I just bypassed the tim limit switch, as I know by feel when the motor is trimmed correctly.
 
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