Power Trim Units

[Glastron1987]

One of my boats has a 4 cylinder 75 Mariner, a 1984 or 1985 motor. The power trim is making a bad noise only when going down starting when it hits the double rods. It actually works OK otherwise, but I take this noise as a warning that something bad will eventually happen. I suspect the pump motor is going, but it might be another part in the unit. I can't tell for sure. I'm probably going to replace the motor and see if that corrects it, but I saw a whole trim unit for sale at a decent price and may go for that instead.

The thing is that unit for sale in from a 1997 150. Visually I see that the fluid fill is different. It seems like Mercury changed designs somewhere around the mid 90's. So I'm wondering if this newer unit will fit on my old motor. Anyone know?

[Dave Strong]

Did you check the oil level?

Dave

[Glastron1987]

Level has been checked, so I doubt it is that, but I can double check in the spring. Also, if it was low wouldn't it fail to work? It just makes a bad noise, it works fine otherwise.

[Glasstream15]

The rod ends on the trim units will make a lot of racket when they get dry. Clean them VERY thoroughly with penetrating oil and solvents to break loose whatever is crudded in there and then about every 3 months put a dab of water proof grease on the ends and on the wear plates. That should take care of it

[phillnjack]

might sounds strange this one, but I would disconnect the power trim ram at the point it is attached to the motor ( top bushing), make sure engine is now in
the fully up position and well secured so as not to drop down and chop your fingers off !!!.
push the button all the way up and all the way down and see if the noise still happens ? I
if no noise from the power trim then send the rams all the way in and tilt motor up and down by hand using the skeg as it makes life easy to check its not the
thru-tube binding and or sticking.
thru tubes get un-noticed and very seldom taken out cleaned up and greased etc, dont rely on grease fittings getting everywhere as it only takes a little bit of dirt
to stop grease getting everywhere.
might be needing new plastic shims if they are worn out ?

could also be binding on the small rod that goes through the tip bushing of trim ram, clean and grease..
had one of these get sticky on just a 60hp merc and the noise was sounding like slow grinding/screeching sound.

just a couple of ideas what it " could" be

.

[Glastron1987]

Those are some pretty good suggestions. Maybe I'll take the boat out of winter storage some weekend and check some of those things out. One thing I should mention is that I did suspect the rod ends at first because they looked pretty much destroyed. Not sure how it happened, as it was before my ownership, but the balls are pretty much gone for whatever reason. Instead of convex they are concave. However, I put globs of grease on them and the bad sound didn't change at all. So that is why I eliminated that as the problem. Will re-check the fluid level, disconnect ram and move it up and down to narrow down the source of the noise. Thanks guys, will post my findings.

[Fishinmymission]

Post Back with findings. My trim for 175hp 1996 does the same thing a crunching grinding sound at a certain point of the down trimming stroke. I also noticed the sphereical tops of my piston rods are all spalled and chipped like you described. Damage resembles fatigue mode from either launching over waves or bumps on the road while towing. Never looked at the mating surface or knew that they existed but apparently there are bolts called striker plates that screw into the swivel bracket. I bet if you replace pistons and striker plates noise goes away.

When I looked at mine they had been this way for as long as I can remember at least 2 or three years and has not gotten worse. I have completely ignored it and not looked into it. Thinking about it now since everything works fine and nothing has leaked I doubt its anything internal. I'm betting those damaged ends are grinding on the striker plates. I don't have my boat nearby to get a better look, I'm now wondering what the damage looks like on the striker plates. I'm probably not going to fix mine but I'm interested to hear about yours.

Glass stream Had A good idea about grease on the rams and or striker plates. Those parts dont get greased so throwing some on every time your in that area could def help prolong their life by lubricating these high pressure surface and preventing galling and abrasive wear that might create stress risers and lead to spalling.

[Glastron1987]

Will post my findings. For now here is an old video of my noise:

http://youtu.be/nAh5S_61rcY

[Fishinmymission]

Saw your video we def have different issues. My pump powers througb my issues no problem and my grinding is louder but only when it starts to touch the pistons. You pump is struggling and slowing down. Either something is galling at that point in the stroke or it's low on fluid someone else could better help.

[mn808gade]

Om trim cylinder rams::Mercs haftobe greased,Yamaha's also need greasing--ALL the time,reason is they mushroom the end of ram (they don't have a BALL BEARING) and if a seal gets to leaking you have to change both cap assembly and ram/piston,MORE $$$. Yamaha's also will studder and splinter end of rams, making them unuseable.Johnrudes need seals/orings/wipers sets( or replacement caps assemblies)sometimes ,but pistons ,never .faststrike units have a bearing to meet ram ends.-th .. P.S. Yamaha V6 units tent to loosen their caps

[Glastron1987]

I always grease the ends for the piston rods. Although the owner before me did not. Are you saying the worn end is causing that noise?

[Fishinmymission]

For me but not the OP. BTW the ends of my piston rods have ball bearings. I greased them and the piston stops (striker Plates) and didn't hear any noise the two times i trimmed it now. Looks like there is no real way to add grease except place them on the balls and spin them. My ball bearings are still spalled/chipped but I'm not replacing them.

[Glastron1987]

My boat is buried in winter storage now. Won't be able to check on things until spring; but will post my findings then. Thanks for the suggestions.