power trim system water intrusion

[monk-monk]

wasn't sure where to post this...the site moderaters might want to move it to another catagory...I want to caution those who have power trim systems on these mercury motors....if you have a leaking Hydraulic Ram, and if that leaking ram sets below the water surface...it will either seep water into the ram in the down position, or it will suck water into the ram when you trim the engine up....if this water intrusion starts, it will dilute the oil in the reservoir, it can potentially over-fill the reservoir with more water than oil, so much to the point, that it can actually push water/oil mixture up into the motor assembly, ruining the motor...i specialize in rebuilding these systems and i see a lot of pumps in this condition...the field and frame assembly around the armature is full of a rusty goo substance, then when the unit sets for awhile, the armature gets locked-up to the field and frame and will not spin...i have taken pumps apart that looked like they were at the bottom of Lake Erie for years...im telling you, if your rams are leaking, you are taking a big risk in ruining your pump or rams....

 

[Chris1956]

Re: power trim system water intrusion

Monk, Did you have that on your older inline six motors, with the pump inside the boat? I never had the trim cylinders sit in the water on those systems. I had many leaks on the external seals, but only oil out, never water in.

I did need to change the oil on my Mercrusier PTT system a couple of times a year to get the water out of it. I never had any issue with the PTT motor.

 

[monk-monk]

Re: power trim system water intrusion

Chris, here's the situation on this: as with my '72 glastron, a lot of boats get larger engines installed on them...like mine, it came with a 70 hp evinrude, but now has a merc 1150 on it...then with the larger engine, you use more gas so then people add another remote tank for fuel supply...i realized the problem with this weight distribution...on a 16' 1/2' boat, i have a bigger engine...2-6 gallon remote tanks that sit under the spashwell...luckly, my boat has good floatation, because that is a lot of added weight, but my Rams DO sit just under water at the ram piston rod seal...NOT GOOD...Like i said, i realize this weight distribution problem so i am switching to an onboard bow tank to counter-balance the boat...BTW...if the water is above the ram piston rod seal...and you see oil leaking...that is a leak in the down cycle...as SOON as you it the "up" trim button, the UP cycle draws back on that down pressure....and into the Ram goes water...it is a matter of fluid displacement and where that fluid goes...if you leaked a bunch of oil out while trimmed down...the water available to the Ram will fill that fluid void...it has to suck something from that down side....

 

[Chris1956]

Re: power trim system water intrusion

Gee, I thought I had the boat that sat the lowest in the water. Up until a few years ago I had the Merc 1500 on it. I never had the trim ram seals under water, and I thought the boat sat low. I have my 18 gal fuel tank in the bow of my 16 foot speedboat, which may have made the difference.

Of course, I now have the Merc 135HPV6. The V6 motor is 100#+ more than the IL6. The PTT is always under water, but no issues with it yet...