Tilt/trim issue--Mariner 45HP

New problem with a used boat/motor. Imagine that.

Friend recently acquired this project. Prior owners said it had been sitting for about five years. Hull is an 87(?) Bass Tracker, engine is a Mariner 45 HP inline four of the same vintage.

When he bought it, the motor was tilted full up, and a transom saver was installed. When he got it home, he lifted up on the L/U, removed the transom saver and the motor went down as if by gravity (not bleeding down).

We worked on it yesterday and today, and the tilt/trim is inop. The switch had broken-off posts (wiring connectors); we replaced the switch and terminals and gave it a try. Click Click. Okay, solenoids are energizing. Checked voltage at the large (power) wires and 12v is available at each.

Connections are tight (some were not before). It is clear that somebody has been messing with this stuff, but not for "quite a while".

Due to the fact that we cannot get it to tilt up (I'm betting it is hydraulic-locked in position) , I cannot check anything at the motor itself, but the downstream side of the solenoid (blue and green large diameter wires respectively) are powered when the switch is in the appropriate position.

How can I get the motor "up" (not necessarily electrically)?

What is the function of the small plastic thumbscrew-type device on the right side of the transom clamp? It is spinning loose, and not attached to anything. Almost wants to fall out, but is "flanged" (flange larger in diameter than the hole it pokes through). I'm thinking there has to be some sort of pressure relief valve somewhere...

Re: Tilt/trim issue--Mariner 45HP

that screw should be the bypass valve that lets you raise and lower by hand. If it was screwed in you wouldn't be able to move the motor anyway except the power trim switch. There are o-rings on the shaft of that screw or should be. Is the trim motor running when you switch? If it is and the bypass is screwed out it won't move the motor. If it isn't running it could be the motor or as you say, hydrolock. can you bleed one side of the cyl?

Re: Tilt/trim issue--Mariner 45HP

that screw should be the bypass valve that lets you raise and lower by hand. If it was screwed in you wouldn't be able to move the motor anyway except the power trim switch.

Click to expand...

Thank you, that is what I was kind of suspecting.

There are o-rings on the shaft of that screw or should be. Is the trim motor running when you switch? If it is and the bypass is screwed out it won't move the motor.

Click to expand...

No, the trim motor does not run at all. The solenoids "click", but that is it. So this plastic thumbscrew is broken off just-below-flush-with-the transom-mount, and now if I can get this out, there is something beneath it that will (maybe) allow me to loosen and relieve pressure. Thank you; that is helpful.

If it isn't running it could be the motor or as you say, hydrolock. can you bleed one side of the cyl?

Click to expand...

Definitely appears hydraulically locked, but getting at the relief valve above should solve that, no? And no, with the motor full "down", (actually tucked under) I can't even see the cylinder.

I'll run with this and will report back. Thanks again and enjoy our Independence Day!

Re: Tilt/trim issue--Mariner 45HP

Partial success!

Got the broken thumscrew out and it was sheared off. Dug a screw slot in the broken-off-flush part and backed it out about three turns. Now the motor can be raised by hand.

But wait...what is this? Hmmm...those six bolts sitting in the transom/splash well are...guess we figured out where those go. Turns out the motor/hydaulic pump unit was not at all bolted to the transom bracket. It is now.

Combine this with the fact that all of the hardware on the two tilt/trim relays was loose, and I think the prior owner had a problem with tilt/trim...

Now, can I remove that motor from the pump unit and test it on the bench? Brushes, cleanup, etc?

Guess we have to go shopping for a manual tomorrow. I'm on vacation visiting an old friend and we're learning some of this stuff together.

Thanks again for the helpful responses.

Re: Tilt/trim issue--Mariner 45HP

dicktaber said:

Partial success!

Got the broken thumscrew out and it was sheared off. Dug a screw slot in the broken-off-flush part and backed it out about three turns. Now the motor can be raised by hand.

But wait...what is this? Hmmm...those six bolts sitting in the transom/splash well are...guess we figured out where those go. Turns out the motor/hydaulic pump unit was not at all bolted to the transom bracket. It is now.

Combine this with the fact that all of the hardware on the two tilt/trim relays was loose, and I think the prior owner had a problem with tilt/trim...

Now, can I remove that motor from the pump unit and test it on the bench? Brushes, cleanup, etc?

Guess we have to go shopping for a manual tomorrow. I'm on vacation visiting an old friend and we're learning some of this stuff together.

Thanks again for the helpful responses.

Click to expand...

Sounds like you're makeing real progress now. I would check with some voltage on the motor before I tore it apart and make sure it isn't something else causing it not to run. Getting a manual is a good idea as you are going to have a lot of fun working on that motor in the future. I bought a "Clymer" manual and wouldn't recomend it. Too vauge and covers too many size motors. Mercury would be best if you can find one. Have fun.................Jerry