Hydraulic trim tilt hose fittings

[Lancer76]

I have a 1976 Mercruiser 233 with the MC-1 outdrive. The high pressure trim tilt hose from the pump to the outdrive manifold burst. I have some good hoses and manifold from a different boat (the new hose) but i see that the flare fittings on the new hoae are bigger than the original hose ( see picture). I don't know the fitting sizes other than i used a 3/8 wrench on the original fitting and a 7/16 on the new question is whether I can buy a fitting reducer to go from the larger new hose to the smaller diameter fitting at the reverse lock and the pump.

 

[kenny nunez]

On that early model all high pressure hoses are 3/16” inverted flare. With the exception of the low pressure plastic line from the reverse lock valve.

 

[Lancer76]

So an inverted flare reducer may work. I will check tomorrow. Thank you.

 

[fishrdan]

I swapped out a newer manifold and hoses (along with a new Oildyne pump) on my 73 Mercruiser and was able to get the reverse lock valve adapters from a local auto parts store, good auto parts store, Napa/Advanced, not Orielly/Autozone/etc.

I did away with the cheap leaky nylon hose and ferrule compression fittings from the trim cylinder to the pump, and used a crimped hose like you have in the pics... No-mo leaks!

 

[Lancer76]

Perfect. Thank you. I'll be doing that today.

 

[TurtleTamer]

Just went through something similar when switching trim pumps (Oildyne plastic-reservoir to a similar Oildyne). My pressure hoses, which I assume are not original to the boat, are 7/16-24 thread. The new-to-me pump has 3/8-20 thread and came with adapters, but the high side adapter broke. Took a lot of messing around at the hardware store and then Napa but I was able to find out those were the thread counts. Then I was able to make an adapter with a short adapter piece and coupler for the 7/16-24 side. The exterior hoses on the gimbal housing/rams are a different animal. I do not know the thread count but in order to plug the transom holes for bleeding I found that the shifter bolts for a 1993-1997 GM F-body Berg-Warner T56 thread in nicely.