Trim Reservoir Milky Oil?

[thebeast]

With the nice weather I thought I would get a jump start on some boat work. Towards the end of last season the I noticed the trim occasionally wouldn't move the drive down. Checking the pump I saw a huge amount of milky oil had leaked out of the reservoir. As a quick fix I just re-filled the reservoir with 5W-30 & did the up/down/up with the bleed screw out to remove the air. It would work fine after this, but then 3-4 outings later the trim would quit working again. Also, after being left alone for a few days with the drive up the drive would slowly go down on it's own (not sure if this indicates a leak at the ram or just some water in the system.) Repeat steps above a few times throughout the summer. Before winterizing I believe we got all the water out.

So now I'm trying to decide where to start figuring this out. Seems like water is entering the hydraulic system while under load... (a leak at the hose coupling maybe)? I checked the hydraulic rams and don't see any obvious cracks. I don't see anything leaking out when moving the drive up & down either. Any tips on how to troubleshoot this?

It's a 1980 mercruiser 898

 

[Boat Doctor1]

Typical- check tightness of all hose connections!! if theyre ok? id suggest resealing the 2 trim cylinders!!

 

[JASinIL2006]

Mine got that way from a loose connection where the hydraulic line enters the ram cylinder. I followed the manual instructions for purging the system - had to do it twice - and that took care of the problem.

 

[88wellcraft210xl]

Make sure the red cap is NOT under the fill cap. If it is, it cause a vacum and will cause the ram to suck in water around the seals. The red cap is there for shipping purposes and should have been remove. Most time it has not.

 

[mr 88]

Well, the only way you get milky oil is by having water infiltration.Most of the time its a bad hydraulic line that goes to one of the trim cylinders.Is the boat in the water or on a trailer at the present time?