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1967 mercruiser 120pre alpha wonbt tilt down

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"I have a 1967 120 mercruiser

"I have a 1967 120 mercruiser with power tilt. This is the old version with only one line to each cylinder. Pump motor runs great in both directions, motor lifts all the way up with no trouble, but will not retract at all, even with alot of weight. Any ideas?"
 
"The hydraulics lift the out d

"The hydraulics lift the out drive just fine with no assistance, but to go down the pump motor runs but the outdrive won't drop. Forgot to mention, I put hydraulic fluid in the system, but reading some other posts, I wonder if I should drain it out and use motor oil or tranny fluid?If I bleed the pressure off the line on either cylinder then I can drop the outdrive with no problem."
 
"It's one of three:

Low

"It's one of three:

Low oil level, low pump pressure or internal resistance in one or both cylinders.

Check the pump reservior oil level first. If the oil level is low, I hope that cures it. Make sure the vent screw is open 1/3 of a turn.

If the oil level is OK, then, since the pump works its hardest to raise the OD, I'm thinking the problem lies within the cylinders; I may be wrong."
 
"Hmm, if I take the lines off

"Hmm, if I take the lines off the cylinders they push in and out by hand with no resistance, is there a check valve or something like that in the pump itself that may be seized up?Oil is full and bled, vent is open. My service manual calls this system a low pressure system, since there is no seperate return line from the cylinders, but has no other info on the system."
 
Use type "A" automatic

Use type "A" automatic trans. fluid if the model # is a 6 digit # followed by an "A". Otherwise use SE20W or 5W-30 or equivlent oil. Was the drive in the down position w/the vent removed when you filled it. Air may still be trapped in it.

Inside the valve body is a slide valve that moves and unseats a checkball to allow fluid to move and lower the drive. The checkball may be frozen or the lighter oil is slipping around the slide valve due to wear. Change the fluid to 5W-30 motor oil if there is not a letter "A" in the model #. It may solve the problem.

High Mileage 5W-30 oil may rejuvenate the slide valve seal. Just a thought.
 
"Ok, I will try the heavier fl

"Ok, I will try the heavier fluid, that seems to make sense to me, thx a ton for the advice!"
 
"Heavier oil still has same is

"Heavier oil still has same issue, is there anything in the pump assembly with the check valves that is serviceable?No mention of servicing any of these parts in my manual"
 
Valve body isn't serviceab

Valve body isn't serviceable. You might see if the slide valve is stuck; nothing to lose doing it. There are some used pump assys. on eBay.
 
"I have a similar problem with

"I have a similar problem with my 74 merc 120hp, but mine will go down but nothing happens when I push the buttons to come up. Any ideas?"
 
"David, you should start your

"David, you should start your own post, you may have an electrical problem.

David, do you have 1 line or 2 at the trim rams ?"
 
"Guy, not sure if that last po

"Guy, not sure if that last post was aimed at myself or David. If at me its similar except I don't have a reverse valve or trim reserve, and only one line comes out of my pump.The one line from my pump goes to a splitter then from there one line to each ram. I ended up taking the whole pump unit of my boat , opened up the resevoir and saw clear evidence that someone had opened up the valvebody assembly, so I can only assume they screwed something up inside there, since my manual says don't open that part up as it is non-serviceable.Found some good dealers with used trim pumps for that era though, thx again for all assistance"
 
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