replacing trim motor on 84 mercury 150

[mwe-maxxowner]

Ill be replacing the trim motor on my 84 mercury black Max 150 next week and I would love any and all help. I haven't figured out how to get the motor up yet so I can get to the motor. Looks like it will be easy when I get the engine up?

My engine leaks down if I have it trimmed up and unlocked for a period of time. I had it beached while hanging out on a dock. Got back to it and motor was in the dirt up to the prop. Didn't pay it much attention and tried to trim up before shoving off. It tried to lift but strained against the mud for a second before I decided to dig it out. An hour or so later it began clicking sometimes when I hit trim up. Then it started going up weakly a week or so later. Then began doing nothing but clicking. Replaced solenoids and that didn't help. So I fried my trim motor :/. I have another ready to go on though.

 

[bobkyle2]

Re: replacing trim motor on 84 mercury 150

The trim motor on a 84 is actually in the boat.

 

[Chris1956]

Re: replacing trim motor on 84 mercury 150

At least some of the V6 motors had the PTT between the Transom brackets. Not sure if they all did, and I am too lazy to look.

That PTT unit should unbolt from the transom bracket. You can then tilt the motor up and lock it. You may need to block up the tilt tube and remove one of the transom clamp sides, to get to the PTT motor.

 

[mwe-maxxowner]

Re: replacing trim motor on 84 mercury 150

The motor is definitely mounted on a cast part of the mount for the motor. How exactly are you suggesting I get the motor up? I'm not sure I completely understand. I've got to get the engine up before I can get to the trim motor or anything mounting it.

 

[Chris1956]

Re: replacing trim motor on 84 mercury 150

Unbolt the PTT unit from the bottom of the transom bracket. It should be about 4 stainless steel bolts, maybe 5/16 in diameter. Then tilt the motor up and the PTT unit will follow it up and hang there. You may need to drive out the retaining pin and remove the PTT assembly completely.

 

[mwe-maxxowner]

Re: replacing trim motor on 84 mercury 150

If I understand correctly, you are basically saying unbolt the motor mount from the boat and tilt it all up. That still wont help, it wont give m more space between the engine and motor?

 

[Wingedwheel]

Re: replacing trim motor on 84 mercury 150

What they are saying is that your motor and the bracket that the PTT cylinder is mounted to are separate pieces. If you unbolt the PTT bracket on the sides of the motor transom mount, then you will be able to put your motor in FWD and tilt everything up. Then you will be able to take the PTT which should be hanging under the tilted motor, off.

 

[mwe-maxxowner]

Re: replacing trim motor on 84 mercury 150

Okay,I think I understand what you mean. Unbolt that metal piece the trim motor is screwed into from the boat,then I can raise it all up. Then the 'ptt' will fall back away from the motor? Is there a way I can relieve the hydraulic pressure so I can raise the motor as it sits? I looked for a way to unbolted the hydraulic ram from the motor or from the 'ptt'. Then I could raise it easily.

 

[Wingedwheel]

Re: replacing trim motor on 84 mercury 150

What is your Ser #?

 

[mwe-maxxowner]

Re: replacing trim motor on 84 mercury 150

I'm not sure. The boat is at a friends house who is helping me work on it. I hope to fix it Tues when I go up there. I can provide a picture of the rear of the boat maybe? I was hoping there was a relief valve, or I could loosen the drain plug or fill plug. Wouldn't hurt to change the fluid anyway I would think. I believe there are caps over the bolt heads holding the hydraulic ram on, which would be why I couldn't find how to unhook it.

 

[mwe-maxxowner]

Re: replacing trim motor on 84 mercury 150

Okay he got the engine raised, but still can't get the trim motor off. He says there is one screw he can't get out. Says it is difficult to explain, but he's tried everything he can think of. He thinks we'll have to remove the engine to get to it. Or figure out how to remove the pin at he bottom of the hydraulic arm. I'd rather not remove the engine so that I don't have to re caulk around it. Once the motor is raised, how is the trim motor removed? I will try to get the serial number tonight.

 

[Chris1956]

Re: replacing trim motor on 84 mercury 150

Normally the trim motor is held on by 4 Allen screws. You may be able to put a 2X4 under the tilt tube, and remove the starboard transom bracket to get at the PTT motor. Of pop the locking pin out of the upper PTT mount, drive out the trim rod and drop the whole PTT unit.

 

[mwe-maxxowner]

Re: replacing trim motor on 84 mercury 150

Unbolted the motor, and tilted hat whole assembly the pump is in up, and we could get to the Allen screw against the boat-shotty design!

I had to transfer the aluminum cylinder with 3 o rings around it to the new motor. Put it back in, and cannot get the system to bleed. It raises till the two short rams are extended, then it barely moves, if any. It does come up if you stand on the engine, which makes no sense to me. I fear I have burnt up the new trim motor by trying to bleed the system. The last time I tried it suddenly started to ease slowly like it did when the old motor quit. I hope an alternator's shop can fix it this time. But that's more time not in the water.

Perhaps it just got too hot? Ill know when I try to bump it n the morning.

Does it sound like maybe those o rings got boogered up somehow and fluid is bypassing them? Tried for hours raising and lowering and letting air out the relief screw. Adding fluid. Nothing helped. I sometimes moves a few inches then basically stops. Sometimes you can wait a moment and it will move a short distance again. Sometimes it will go up "almost" nomrally if you stand on it.

 

[mwe-maxxowner]

Re: replacing trim motor on 84 mercury 150

I want to try to remove the "Ptt" assembly completely so that I can attempt to inspect and replace any o rings I can comfortably remove and replace. I have figured out how to unbolt the unit from the transom brackets, and unbolt the brackets from the boat and tilt it all up, but where do I look for a pin to remove the pump and motor from the boat. Since it all worked normally before I removed the motor, my problem has to lie in the o rings around that cylinder that attaches to the end of the trim motor, no?that is all that has been altered or messed with in any way. Those not sealing well could allow fluid to leak past and it wouldn't raise properly?

When I saw that they were there, I should have gotten more, but I wanted to hit the lake tomorrow and I was in a hurry.

 

[Chris1956]

Re: replacing trim motor on 84 mercury 150

There should be a pin in the center of the upper PTT mount. It locks the trim rod to the PTT unit. Drive it out from the transom side of the boat, if you can. Use some penetrating oil on it first. The proper method to bleed that PTT unit is to tilt it all the way up and lock it up. Lift by hand if need be. Wait 5 minutes for air to bubble out and refill. Now run her down and up and repeat. Be sure to wait the 5 minutes each cycle for the air to bubble up/out.

 

[mwe-maxxowner]

Re: replacing trim motor on 84 mercury 150

Thanks! I found there was a small set pin holding the main pin in the upper pivot point of the large arm. I finally got it all off. My trim motor is OK. There was a bad connection at the battery which somehow decided to act up instantaneously. Was good one minute, acres dead the next. Which is how the old trim motor acted when it quit.

Anyhow, back on topic. I'm assuming the aluminum cylinder that attaches to the trim motor is the pump itself. I replaces all the o rings on this. I now want to get the cylinders apart while its all off the boat and on my workbench and replace the seals in them. I thinking my problem lies inside them. I think fluid is bypassing the seals in the cylinders. Which could explain why it works better if I stand on it. It puts pressure against those seals again. I can push on one of he small cylinders and the other one extends.

I don't, however, understand why it was fine before I removed the trim motor, put it back in, and I have this problem. I did have a leakdown problem before, but only a small one. It would leak down from full up over a few hours. I planned to fix that this winter .

If I can get these cylinders apart while its off, and replace those seals, I will be good to.go!

When I wait the five minutes, do I remove the fill cap to release te air? Or the manual release valve?

 

[mwe-maxxowner]

Re: replacing trim motor on 84 mercury 150

 

[Chris1956]

Re: replacing trim motor on 84 mercury 150

To bleed the PTT, leave the manual pressure relief screwed in tight. The reservoir cap should be on during the cycle down and up. Wait the 5 minutes and open the cap and refill the reservoir and replace the cap. Repeat until all air is gone out of system

 

[mwe-maxxowner]

Re: replacing trim motor on 84 mercury 150

Thanks. Anyone know how to get the cylinders apart to change the seals inside them? I changed the seals on the pump, but I don't think they were my problem. They looked OK. I think the new fluid maybe washed the old seals or something in the cylinders. Its all I can figure that makes sense. Does that little pump (cartridge pump) ever quit working properly for any reason?

 

[mwe-maxxowner]

Re: replacing trim motor on 84 mercury 150

Is there a cap on the end of the cylinders that is removable somehow allowing me to service them? The system would work great till the two small cylinders were extended and it was all up to the long middle cylinder. Then it didn't really wanna push up.

I found a guy reconditioning used ones and selling them (the whole unit), so I'm sure it can be taken apart.