First time out this season with a 25’cat came back in after a few hours put on the trailer opened the drain plug and a bunch of oily water came out. The side of the engine closest to the trim pump had an oily spray spray All the way up the side. The reservoir level was also low. Cleaned it all up filled the reservoir back up and ran the trim up and down multiple times with no leaking. Any idea’s ? Thanks

I'd assume you need resistance to build up enough press to see a leak like you describe. It doesn't take much press to move drives when sitting still. If you know for sure that the trim rams bottom out before the drive does, you could run trim pump to the point the trim rams run out of travel. You will build max pressure at that point. Leak should be obvious. May need 2 people for this since leak will stop as soon as press bleeds off. Alternatively, you could disconnect trim rams from drive or remove lines at trim cyls and cap them off with proper hardware, then build up press and leak check.

Thanks for the info! I cleaned everything and let it sit and oil is seeping from somewhere around the valve body. I was just concerned with it spraying 2 ft.
I have it out and believe i am going to order a whole new pump tank assembly, solenoids could be the next thing to go on a 25 year old boat. Thanks again!

When filling, this is something to pay attention to - make sure the drives are down. If they're up and you fill reservoir, you're almost guaranteed a mess when the drives go back down (the excess fluid has to have somewhere to go). I had the same problem with mine - the fluid made it from the rear seat bulkhead to the back of the transom. At first I thought the transmission was puking but did some careful looking and found that it was the port-side drive trim reservoir.

If you're using Merc reservoirs, the caps like to leak too - I picked up some vented caps that allow air in and out, but keep the fluid in. I'm pretty sure I got them from CP Performance.

You may be right, I had checked all fluids last fall before i put it up for the season but can’t remember if the drive was up or down. I am going out this weekend so hope all is well. Thanks