120 Mercruiser I/O Trim hydraulics

[sunk ship]

I have a 1973 120 mercruiser pre alpha I/o and it is squirting oil from the trim control valve assembly and I can't seem to find the correct size o-rings. Anyone know if there is a o-rings kit available based on my trim unit or engine type or some way to reference where to get the o-rings I need because I've bought the standardized metric and standard multi o-ring kits and still can't get the control valve assembly to stop squirting. The serial # of the motor is 3645749 and it is a 18 ft bottom SS StarCraft if that helps any at all.

 

[Alumarine]

Try merc part no. 25-48171 or Sierra 18-7168-9.
.364" x .070"
The parts are listed by drive serial no.
marineengine.com/parts/mercruiser-sterndrive-parts/120140-19701977/2791957-thru-4893634/hydraulic-pump-assembly-complete/

 

[kenny nunez]

The 4“O” rings under the pump can also be obtained from a NAPA store. They have them in a box by size and can be matched up. Before you reinstall the block put a straight edge across the bolt holes, you will see that the block is distorted. Mount it in a vise and with a good file smooth it out. The 3k lbs of pressure over time is what causes the distortion. If you do not smooth it out it will blow out again.
If you are talking about the reverse lock valve you are in trouble. They are NLA. What has happened is the inside of the valve is worn and the rotating part is moving around too much. I have seen some on ebay in the past. Later models sometime after 76 eliminated the valve and added another check ball and spring in the block under the pump.

 

[sunk ship]

I think it's the four o rings that are bad, but I've had this down for so long now and have tried so many different sizes I'm not sure what the original size is anymore. I've been trying to go off of the indentions but it hasn't worked so far. I wish I knew what size was called for, like maybe Id and od, or od and thickness or something.

 

[Scott06]

I think it's the four o rings that are bad, but I've had this down for so long now and have tried so many different sizes I'm not sure what the original size is anymore. I've been trying to go off of the indentions but it hasn't worked so far. I wish I knew what size was called for, like maybe Id and od, or od and thickness or something.

See post #2 I think those are the dimensions …

 

[sunk ship]

See post #2 I think those are the dimensions …

Thank you. I somehow actually missed that whole post. Guess that's what I get for using a phone instead of a computer. Hard to see on a phone. Getting old and blind, lol