Old Merc Power T&T unit rebuild???

[69MyWay]

I've got a 1979 115 Merc with tilt and trim.

It sags down after a bit and won't hold a steady position.

Electrics are good - fluid is good.

Can I get a rebuild kit for they hydraulic unit that mounts inside the boat?

My local hydraulic supply places can do the ram rods if need, but nobody knows anything about the pumps.

[69MyWay]

I found a link below that has a blow up of the pump (I think this is the correct one). Looks like the valve body may still be available, but it is pricey.

https://www.marineengine.com/parts/mercury-outboard-parts/1150-115/4855153-thru-5314655-usa/hydraulic-pump-assembly

I have to wonder if the part number 3 - Can Valve - could be the problem?

I suppose it could be the rams, but hard to say. I can raise the engine and wait a while it will drop back down slowly - you can almost see it...just wait an hour or two and it will be all the way down.

[Tom Smyth]

probably the rams leaking down..

[69MyWay]

probably the rams leaking down..

Any idea how to test?

I also see there is an aftermarket assembly, but I can't get any details on the fitting size and type.

Power Pole Sportsman Anchor Tilt Trim Motor Pump & Reservoir

[Dave Strong]

Make sure there are no leaks, O-rings #1 go bad and have seen if the hose fitting where the up hose connects to the valve body is the least bit loose will cause this. If those are good Tom is probably correct and trim rams have a bad O-ring.

Dave