1997 175 Merc Offshore Trim Motor Replacement

[Ben Heiser]

All:
The top of my trim motor is getting corroded...looking to do some spring preventative maintenance and change it. Looks like a PIA.

The service manual says to remove the right side motor plate to get to the rear bolt...wondering if taking the pin out of the trim cylinder and rotating the trim unit out may be easier? Any tips?

thx.

Ben

 

[DennisG01]

Have you physically tried to get at the rear bolt? Sometimes you can be pretty ingenious with extensions and whatnot. Your idea (tilt cylinder, not trim, fyi) would be easy enough to try. Wouldn't be too hard to lift the engine and push it back from the transom enough to access the bolt, either.

You may be able to remove the entire trim/tilt assembly with the engine still in place. On my Yamaha, when it was time to rebuild the assembly, the manual said I had to pull the engine off to remove the assembly forward. After looking at it for a few minutes, I was pretty sure I could remove rearward without taking the engine off. Only took about 30 minutes to do that. I have no idea if you can do that - although from the picture it sure looks like you can. Point is - don't always trust what a service manual says - there are some times when it is not entirely correct.

 

[seasick]

It looks like the assembly would tilt aft if the center ram pin is removed ( after setting the lock lever!). What you probably can't get to is the the cable which runs up into the lower cowling and may cover the section of the motor where the relay is.
When you say Motor Plate, do you mean lower cowling?
By the way, those Merc trim motor housings are notorious for rusting.

 

[Ben Heiser]

It looks like the assembly would tilt aft if the center ram pin is removed ( after setting the lock lever!). What you probably can't get to is the the cable which runs up into the lower cowling and may cover the section of the motor where the relay is.
When you say Motor Plate, do you mean lower cowling?
By the way, those Merc trim motor housings are notorious for rusting.

I am fearing the rust on the outside means it’s working it’s way inwards...if I am wrong correct me.

When I say motor plate I mean RH side mount bolted to transom.

As for trying to get to the bolt before removing anything...I will be just hoped someone had attempted it prior!

Also, seems a lot of “cheap” trim motor solutions on Amazon...not great reviews will be going for Merc OEM replacement..

 

[Ben Heiser]

Well, I was able to get the trim motor replaced without removing the starboard bracket from the boat. I purchased a 6” long 6mm Allen with a 3/8 socket on it....knocked the socket off and used a 1/4 socket on it and was able to get to the rear bolt. Success!

Now I have realized the tilt cylinder cap seal is leaking....can I change this cap seal without removing the cylinder? I think I can raise the motor all the way up, take the top pin out and rotate the cylinder all the way past the motor to point “down” towards the ground and undo the cap. The manual yet again says to remove the starboard bracket to get the bottom pin out...but I don’t need to change those seals.

Any suggestions appreciated and thank you!

 

[Sparkdog118]

I believe you are correct. If you take the top pin out and put the motor on the lock lever, you can run the trim motor down a little to retract the ram. The ram can now be pivoted out so you can get the top cap unscrewed. May be a good idea to loosen the ram cap before you take the top pin out. Also loosen the pressure relief valve Screw a few turns to take the pressure off the cap so it is not so tight and it doesn’t spray everywhere when you break it loose. It also allows you to equalize the pressure while removing the ram from the cylinder.

 

[DennisG01]

Good - glad the extension idea worked.

I guess whether the tilt cylinder will tilt far enough forward will depend on the clearance at the bottom between it and the boat. What about the hydraulic line? But it will only take you a couple minutes to figure that out.

Are you sure you don't want to just pull the whole assembly - as I mentioned above, it sure looks like you can. It's so much easier (and cleaner!) to be working on it at your workbench.

30 minutes and it was out:

 

[Ben Heiser]

Good - glad the extension idea worked.

I guess whether the tilt cylinder will tilt far enough forward will depend on the clearance at the bottom between it and the boat. What about the hydraulic line? But it will only take you a couple minutes to figure that out.

Are you sure you don't want to just pull the whole assembly - as I mentioned above, it sure looks like you can. It's so much easier (and cleaner!) to be working on it at your workbench.

30 minutes and it was out:

I could pull the whole assembly, but that also involves removing the starboard engine bracket. Mercury did not make this servicing easy...which was what I originally ran into with the trim motor.

The hydraulic line, is in the base of the cylinder in the pin. The cylinder should rotate OK towards the rear of the boat and down to pull the rod out (I think).

 

[DennisG01]

The assembly might actually come out easily. I can't say for sure as I'm not there to look at it, but check it out - the service manual isn't always correct. If I would have believed my service manual and what everyone was saying on forums (most were just re-spouting what they heard somewhere else) then I should have removed the engine completely. But I inspected in and decided that it should work - and it did. I'm looking at your first picture and sure does look like it will slide out - from what I can see, anyways. Do you physically see anything that would prevent it from coming out as an entire assembly? Heck, the inside of your bracket area looks more open than mine!

FYI, what you're experiencing (removing the trim motor, etc)... that's pretty much the name of the game with all brands. Some are even harder!

 

[Sparkdog118]

The ram will rotate down just fine. Just crack the cap loose before you take out the top trim pin. The ram will slide out of the cylinder easily if you open the trim release screw. Some rams have a bolt and some have a nut at the bottom. Just place the bolt or nut in the vise and stick a long rod in the trim pin hole to remove the bottom check valve assembly. The cap n seals will slide off via the bottom of the ram. Reload the cap with new seals and slide it back together. The bottom of the ram is tapered for easy seal installation. Just lube it up with a little grease so the new seals slide easily. I always use loctite 271 on the bottom ram bolt with the installation. Slide the ram together, screw in the cap n install the top trim pin, the aluminum locking pin and the trim sender and you are finished. Add fluid and the unit will self bleed by running the trim motor up and down with the trim release tight. Sometimes you help it Bleed with loosening the trim release screw and let it fall from the up position. Keep adding fluid to the unit (full up position) as the air is bled out.

 

[Sparkdog118]

Here is a diagram of the ram.

 

[Sparkdog118]

www.boats.net/catalog/mercury/outboard-by-hp/150-to-200hp/0d935000-thru-0g610049-usa-cat-90-80856794/power-trim-components

 

[Ben Heiser]

Yup, ram rotated down just fine and the tilt cylinder seals all replaced. The only odd thing was the scraper seal in the cap (the one that is visibile) didn't take much force to press in....I'll have to just watch it and if it starts to push out I'll put some Loctite around it and push it back down but so far so good.

Did the trim cylinders at the same time, and they assembled flawless. They weren't leaking, but man the scraper seals looked back.

FYI...that Mercury spanner tool isn't that great. Needed almost a third hand!

All maintenance done! (for now) Thanks for everyone's helps...

 

[DennisG01]

Good deal!

I'm not sure if the Merc spanner tool is any different than the Yamaha I have, but they generally require a lot of downward force and keeping the tool perfectly level to stop the pins from popping out.

We talked about this in some other threads (quite a few, actually) about this type of job and one thing (tip) that can help is slipping a piece of PVC (cut a slot out of it to slide it over the extended tilt ram) over the ram, and then "tilt" down to keep pressure on the tool head.

 

[seasick]

I am pretty sure that the Marine Tech wrenches I have for my SX Yamis will not fit on my Optimax's ( hmmmm. what is the plural of Optimax?. Opimaxes?)

 

[DennisG01]

Optimi (eye)?

 

[seasick]

Sounds good to me.. Optimi