Repairing Trim System on 90HP Mercury

[l008com]

OK so I have an older thread on this topic where I was just gathering information, this thread is for me actually doing the repair.

The issue, the trim doesn't work. You hit the button and you get god-awful loud sounds coming from the system. I'm working under the assumption that the issue is the trim motor. I do plan to test it with the motor detached from the rest of the trim system, but that comes later on.

The #1 piece of advice people give on these forums is to buy a manual. Well I bought a manual (Seloc 65 to 89 mercury outboards) and it's practically useless so I'm going to need more help. Starting with removing the trim system itself so I can drain it, replace all the O rings, and get it ready for a new trim motor (assuming the problem turns out to be the motor).

So step one is to drive out the cross pin, that secures the retaining pin for the tilt piston. The illustration shows someone hammering the pin from the back, towards the bow. But this pin has a large head that I'm hammering, so of course it won't go any deeper ones I've hammered it somewhat flush. Did my manual make a mistake, and was I supposed to somehow pry this pin out instead of hammer it in? The instructions for reinserting it are the same, hammer it in from the back, towards the rear. I don't see how this pin could stay in if the same way you get it in, is the way you get it out.

Here is a picture of the Pin in question. It was sticking out maybe 1/4 of an inch towards the camera before I bashed it flat.

 

[The_Kid]

Re: Repairing Trim System on 90HP Mercury

There are 2 different kinds of pins used on trim units. A trilobe and a groove pin. The trilobe has a center pin that when tapped in spreads the 3 tips to hold the pin in place. Kind of like a pop rivet in reverse. To remove a trilobe you us a small punch to drive out the center pin "towards the bow" and then use wire cutters to pull the remaining part of the pin out towards the rear.

A grove pin is just held in by friction. It's driven in from the rear and also removed from the rear. Now that yours is almost flush you probably won't be able to remove it. All is not lost. The info below is out of the Mercury service manual.

"If the trilobe pin proves difficult to remove
in Step 4, the upper pivot shaft may
be driven forcefully from its bore, shearing
the trilobe pin. Make sure all trilobe
pin remnants are removed and the pivot
shaft and trilobe pin bores are cleaned
and inspected for damage."

 

[l008com]

Re: Repairing Trim System on 90HP Mercury

There are 2 different kinds of pins used on trim units. A trilobe and a groove pin. The trilobe has a center pin that when tapped in spreads the 3 tips to hold the pin in place. Kind of like a pop rivet in reverse. To remove a trilobe you us a small punch to drive out the center pin "towards the bow" and then use wire cutters to pull the remaining part of the pin out towards the rear.

A grove pin is just held in by friction. It's driven in from the rear and also removed from the rear. Now that yours is almost flush you probably won't be able to remove it. All is not lost. The info below is out of the Mercury service manual.

"If the trilobe pin proves difficult to remove
in Step 4, the upper pivot shaft may
be driven forcefully from its bore, shearing
the trilobe pin. Make sure all trilobe
pin remnants are removed and the pivot
shaft and trilobe pin bores are cleaned
and inspected for damage."

Looking at the diagram, it appears mine is simply a groove pin. But, if you get it in and out both from the rear D) then what did I do wrong?

 

[Chris1956]

Re: Repairing Trim System on 90HP Mercury

If you unbolt the PTT system from the transom bracket, you can swivel it backwards,possibly exposing the other end of the pin.

I ended up blocking up the tilt tube to support the motor, and removing the starboard side transom bracket, to allow me to remove the bolts and drive out the pin.

 

[The_Kid]

Re: Repairing Trim System on 90HP Mercury

Looking at the diagram, it appears mine is simply a groove pin. But, if you get it in and out both from the rear D) then what did I do wrong?

Maybe some poor working on my part. Think of it as if you were driving a nail into a board. You drive it in from the rear towards the bow. To remove it you pull it out like you would a nail. You're trying to remove it by driving it all the way through the board.

 

[l008com]

Re: Repairing Trim System on 90HP Mercury

Here's a very important question, where do I get a replacement pin?

 

[l008com]

Re: Repairing Trim System on 90HP Mercury

So I'm trying to forcefully remove the big pin, sheering the little pin. It's not really working though. I'm using a heavy hand mallet and a large sledge hammer. I'm not having much luck though, any other ideas? Also I'll still need a replacement pin, any thoughts on that?

 

[Chris1956]

Re: Repairing Trim System on 90HP Mercury

Did you give driving out the pin a good try? Use some penetrating oil on it? How about drilling it out?

I would be afraid to crack the casting, with what you are doing.

 

[l008com]

Re: Repairing Trim System on 90HP Mercury

You mean the small pin? Theres no getting it out, it is totally flush with the casing around it. Going by my WRONG manual, I hammered it as far in as I could get it.

 

[l008com]

Re: Repairing Trim System on 90HP Mercury

Hey it worked! After lots of . . . pounding, the pin finally came lose. I didn't have time to remove the rest of the system, but as long as my manual doesn't have any more wrong instructions, that shoudl come out piece of cake!

 

[l008com]

Re: Repairing Trim System on 90HP Mercury

OK now that the trim unit is going to be easy to remove, anyone know where I can get one of those previously mentioned rebuild kits for this trim system? I've looked but haven't found any. What comes in them besides new O rings? My manual lists all the O ring sizes so technically I could just buy them individually, but my trust level of this manually is pretty low right now, I'd rather buy a kit that has everything I need already you know.

 

[The_Kid]

Re: Repairing Trim System on 90HP Mercury

You can check http://www.ishopmarine.com/ishop/store/mercury/ to see if they have the parts you need. I got my manual release valve and knurled pins from them. They stock some valve/O ring assemblies.

 

[l008com]

Re: Repairing Trim System on 90HP Mercury

OK new situation. I was just now getting around to removing the trim unit. 6 bolts hold it on. 5 came out, one sheered the head right off the bold. Also, on the 5 that did come out, lots of white powder came out with it. What is this white powder, and any suggestions for removing whats left of this bolt? I figure I"ll try to turn it into a flat head, since i have a dremel and my socket set has a nice set of flathead sockets. But I'm definitely open to other suggestions.

 

[l008com]

Re: Repairing Trim System on 90HP Mercury

Now I'm getting angry. That last bolt is being a real pain in the ***. I tried spraying it with WD40 and then dremeling it into a flat head, then using a socket with flathead bit to remove it. But that did not work at all. I'm not sure what else to do. I don't want to try to drill it out, because i'm pretty sure I'll destroy the trim unit in the process. The bolt is in there really tight though. I mean, tight enough that trying to remove it snapped the head right off.

 

[l008com]

Re: Repairing Trim System on 90HP Mercury