mercury 70hp 1988 Power trim help

appleo

Petty Officer 1st Class
Joined
Jul 19, 2012
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388
Bought used motor
Trim stuck in UP positon

1 big ram plus 2 bottom rams


i found blue green black wires to trim pump direct
Battery jumpered green plus black neg no reply
Battery jumpered blue plus back neg no reply

yes i have the mechanical tilt lock relaxed

loosened relief plastic screw , small bit of oil drained then stoipped

tried the battery again no movement

battery sparks when i connect the jumpers so it must be drawing current

large ram still stuck up position... i need to get it down to put motot on stand


any other ideas?


are the two allen bolts the only thing holding on the electri pump? i remove them and the pump wont budge
i dont want to hammer it

thanks for what you can offer

DANMAN
 
Joined
Feb 17, 2012
Messages
2,906
Re: mercury 70hp 1988 Power trim help

i thought there was 3 bolts holding the electric motor on. Make sure you tie the motor up so it doesnt drop on you while you are working on the tilt.
On the right side transom mount (looking from back of the boat) theres a relief screw undo it 2 turns (do not undo it past 2.5 turns) and this should allow the big ram to retract but you may want to pull the pump first because theres hardly any room to get the motor even when its trimmed up.
 

appleo

Petty Officer 1st Class
Joined
Jul 19, 2012
Messages
388
Re: mercury 70hp 1988 Power trim help

i thought there was 3 bolts holding the electric motor on. Make sure you tie the motor up so it doesnt drop on you while you are working on the tilt.
On the right side transom mount (looking from back of the boat) theres a relief screw undo it 2 turns (do not undo it past 2.5 turns) and this should allow the big ram to retract but you may want to pull the pump first because theres hardly any room to get the motor even when its trimmed up.


Motor is off boat on crane
Electric motor has 2 Allen head bolts. I see a stainless hex bolt on backside but that appears part of pump casting. It is 3/8 approx.shpuld I remove it?


I removed the plastic 9/16 relief screw. It has a plastic shaft on backside approx 2 inches long. Some red fluid came out a tablespoon. I put the screw back
 

RRitt

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Joined
Mar 30, 2006
Messages
3,319
Re: mercury 70hp 1988 Power trim help

if you connected blue-black (or green-black) directly from motor to a good 12v battery and nothing happened ... then the trim motor is bad. However, be advised the when the blue wire is connected then the green wire must be open. Even grounding the green wire will energize the down electro-magnets and the motor will try to spin in both directions at once. It can't so it just sparks, smolders, warms up, and eventually bursts into flames causing a massive forrest fire that consumes the entire eastern seaboard. Well, okay, maybe not that bad but it still doesn't work.
 

appleo

Petty Officer 1st Class
Joined
Jul 19, 2012
Messages
388
Re: mercury 70hp 1988 Power trim help

if you connected blue-black (or green-black) directly from motor to a good 12v battery and nothing happened ... then the trim motor is bad. However, be advised the when the blue wire is connected then the green wire must be open. Even grounding the green wire will energize the down electro-magnets and the motor will try to spin in both directions at once. It can't so it just sparks, smolders, warms up, and eventually bursts into flames causing a massive forrest fire that consumes the entire eastern seaboard. Well, okay, maybe not that bad but it still doesn't work.

Well I tried the release screw again and the big piston retracted when I applied some weight

I will try the electrics again tommorrow once I get the motor on the stand.

If nothing I will try to remove the square pump

Yes green grass blue sky..only one can be plus at a time

I only see two alen screws on the pump motor
 

starkyb

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Apr 21, 2007
Messages
217
Re: mercury 70hp 1988 Power trim help

I just changed mine on a 75 horse Mariner last night. I bought a brand new one on eBay for $150. After you remove the screws there is a little slot where you put a screw driver in and pry it up. The new one comes with its own solenoids so remove the old ones and attach the new solenoids where the old ones were. Before you tighten the motor back down make sure it is all the way down and straight, otherwise you could crack the tabs that hold the screws. And of course disconnect your battery before you start.
 

RRitt

Captain
Joined
Mar 30, 2006
Messages
3,319
Re: mercury 70hp 1988 Power trim help

....

Yes green grass blue sky..only one can be plus at a time

I only see two alen screws on the pump motor

the other one can not be grounded either. The unused wire MUST be an open circuit. The motor has a center tap armature where green and blue windings meet. If you ground green, then the center becomes 6v and both sets of windings are energized.
 

appleo

Petty Officer 1st Class
Joined
Jul 19, 2012
Messages
388
Re: mercury 70hp 1988 Power trim help

Yes I am aware unused wire floats
 
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