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Trim problems

buttzy

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Hi I have a 1975 mercruiser th

Hi I have a 1975 mercruiser that the trim will go up but not down. I was hoping someone could help me with this. i can manualy lower it by unhooking the hydrolic line at the trim motor. I took trim pump and motor apart to look at and everything looked fine.
 
"Jon,
Sounds like your down l


"Jon,
Sounds like your down limit switch is faulty. There are two limit switches... one for full UP and one for full DOWN. My guess is the switch is faulty and thinks you are in the down position already."
 
"How the trim/tilt works--Befo

"How the trim/tilt works--Before you tear anything apart or replace wiring and switches, test it out; first by visual inspection by pulling back and forth on the wires while operating the swithes and then test with a meter. At the commander switches, the red wire will always have 12 volts. The green wire gets 12 volts when the trim toggle is held down. The blue wire gets 12 volts only when the toggle is held up or the trailer switch is pushed in. The purple wire is part of the limit switch circuit.

If the switch voltages are as they are supposed to be then go to the trim/tilt pump assy. and make sure the purple wire connector (single wire) and the blue wire connector with two blue wires on one side of the connection are not corroded or loose. These are the trim position and limit switch wires. Pull them apart and inspect; they should be clean and tight; reconnect them.

Next check the three wire connector (RED, BLUE & GREEN) at the pump assy. This plug can vibrate loose and cause your problem. Pull it off and see if the pins are clean and not corroded; reconnect it.


The RED wire in the plug sends 12 volts from the pump assy. to the toggle up/down and trailer up switches. The BLUE & GREEN wires bring 12 volts from the toggle trim/tilt and trailer switches to the two solenoids on the pump assy.

The GREEN wire goes to the DOWN solenoid while the BLUE wire goes to the UP solenoid.

Did you check the switches with an ohmmeter? The trim/tilt switch is a 2-way switch and will show continuity only when it is toggled in each direction between two of the wires.

Up toggle connects the RED wire to the BLUE wire. Down toggle connects the RED wire to the GREEN wire. The TRAILER UP switch also connects the RED wire to the BLUE wire.

The OD trim limit switch will only send voltage to the trim/tilt switch in the upward toggle position if the OD limit switch is below the adjusted trim limit that keeps the OD being out of the water.

To test the limit switch circuit, lower the OD to the down position and slowly raise it with the trim toggle up until it stops. Then measure the distance between the trim cylinder attaching bolts. If the distance is approx. 22 +/- 1/4 inches, then the trim limit switch is adjusted properly and the commander trim toggle switch is working in the up/down mode.

Go to the trim/tilt pump assy. and make sure the purple wire connector (single wire) and the blue wire connector two blue wires on one side of the connection are not corroded or loose. Pull them apart; they should be clean and tight; reconnect them.

Next check the three (RED, BLUE & GREEN) wire connector at the pump assy. The RED wire in the plug sends 12 volts from the pump assy. to the toggle up/down and trailer up switches. This plug can vibrate loose and cause your problem. Pull it off and see if the pins are clean and not corroded; reconnect it.

The BLUE & GREEN wires bring 12 volts from the switches to the two solenoids on the pump assy. The GREEN wire goes to the DOWN solenoid while the BLUE wire goes to the UP solenoid.

Disconnect the trim/tilt assy. wires from the battery and then check each of the nuts and studs on the solenoids for clean and tight fittings. Each solenoid has three wires and the buss bar connected to it. The bases of them have a black ground wire and a small blue wire to one and a small green wire to the other.

On top of each solenoid, the large BLUE wire from the pump motor attaches to a large copper stud with the solenoid that has the small blue wire at the base while the large GREEN wire from the pump motor attaches to a large copper stud with the solenoid that has the small green wire at the base.

The other copper solenoid studs are connected together with a copper buss bar. One of the two studs will also have a funny looking 110 amp fuse attached to the bar. The large RED wire from the battery connects to the 110 amp fuse. This large red wire is the power for this buss bar. A small RED wire attached to the bar stud sends 12 volts to the switches which in turn sends the 12 volts to the solenoids which turns on the pump motor.

Important: if the studs on the either solenoid are dark and not like a clean penney, especially the BLUE wired solenoid, this solenoid is failing due to age and/or a loose bottom copper stud nut. The dark color comes from heat generated inside of the solenoid by the contactor because it is arcing like welding similar to points wearing out. Change the solenoid."
 
"Mine works fine now after a m

"Mine works fine now after a mechanic friend told me to bleed the air out of the cylinders. that was the easiest thing to do first, for me."
 
"2007 Merc 4.3L V6 in a 22&#39

"2007 Merc 4.3L V6 in a 22' Hurricane Deck Boat. Started hearing a slight, yet noticeable clicking noise from prop when trimmed up (not in trailer mode) and running at around 800-1400 rpms. Never hit anything with prop; nothing caught up in prop; prop appears normal; no steering issues; etc. Clicking sounds as though prop is hitting something metallic, yet it seems to be free of any obstructions and moves freely (without noise) by hand when docked in neutral with engine off. Noise seems to disappear when trim is down and rpms are higher. First noticed noise at end of day on water with a full load of passengers on board. Any ideas or suggestions to help direct me toward the root of the problem would be appreciated. Thanks!"
 
"Carl, am I reading correctly

"Carl, am I reading correctly that's a 2007 engine and boat????? If so, it sounds like the dealer needs to take a look at it for you. When there is a metallic noise at one end of the trim range and not the other, I've read that it more than likely a bearing or U-joint issue."
 
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