Tiller very hard to turn under power

Up until now, there's always been other things that seemed more important but now it's time to get this resolved. I've got an 86 mariner 25hp. When the motor is in neutral or not running, it is ridiculously easy to turn from full left to full right. No clicks, rough spots, biding, or anything. Start it up and as soon as you start to accelerate, it's like someone cranked the tension adjustment all the way tight. It's so hard to turn that you can't make slight adjustments to the steering. You have to gradually increase pressure on the tiller until it finally moves but if you not very careful, it suddenly breaks free and you end up over steering. I've pulled and tugged and pressed and pried on it trying to find something worn or binding but I can't seem to find out what's causing this. If I tighten the steering tension adjuster the least little bit, it's almost impossible to steer when on plane. Has anyone ever run across a problem like this or have any ideas what might be causing it?

That engine does not have an adjustable trim tab?

Binding up under pressure - have you greased it lately?

It shows a trim tab in the parts diagram but there isn't one on it. But the problem isn't that it pulls against you when your running. You can open the throttle wide open and let go of the tiller and it won't budge in either direction without substantial pressure on the tiller to one side or the other.

I've greased every fitting on it several times. Most recent was 2 weeks ago.

Hmm...I've got the same motor in a 20hp so I'll take a closer look at it tonight when I get in and see if I can find anything that would cause it to do that.

Here is a link to the parts diagram. https://www.boats.net/parts/search/MercuryMarine/06535686/274/160/SWIVEL%20BRACKET%20ASSEMBLY/parts.html I'm thinking you may have a bad bushing, is there any lateral play in the swivel bracket when the motor is off (not running)? It wouldn't be much...1/8" of play or so would be my guess.

I'm suspecting it to be something like a worn bushing/bearing on the pivot shaft or at least something like that but I haven't found any play in it so far. I was looking for something more substantial than 1/8" play but maybe that's all it takes to cause something like this. I guess I need to look a little closer.

Am thinking 1/8" play would be very excessive. Discount the mount deflection when checking.
But, you pretty much have to be on track in your thinking that there is an issue in that area.

Looking at the diagram and trying to remember the relative sizes of everything on my motor I think there is at most 1/8" between the shaft and the side of the steering housing...so you wouldn't see much play.

Well I've pushed, pulled, and tugged on it from every angle I can, and the only movement I can find is between the tilt adjustment pin and it's locking mechanism. I even tried to apply forward pressure to the foot of the motor (trying to simulate under power) but it wasn't enough to cause the motor to bind. I did notice that the grease that I put into the pivot fitting only comes out the bottom of the pivot shaft, and none at the top. It actually looks pretty dry at the top. Not sure if that's a problem or not.

As you say, the grease might not be flowing through. Can't see how it would move so easily when not running and then only bind up when running, but, boats are strange things sometimes.

Might be worth your while to take it, while on its trailer, up to the local service station ( is there such a thing anymore?) and have someone with a power grease gun shoot some through.

Their pressure is probably more than a standard manual grease gun can put out. Can't hurt and they might not even charge you at all for one squirt of grease.

richg99

If there's a "service" station still left in this country, I haven't run across it in the last 10 years or more. We've got 2 convenience stores with gas pumps and a third one that just opened but don't have their gas working yet in this little bump in the road town. I've gotta go up to the ford dealership in the morning to borrow a tool so I'll see if they might have one back in their shop. My truck has 2 lower ball joints that are popping like it's the 4th of July and I can't go fishing again until I get it fixed. #-o

If the engine had seen service in salt or brackish and not been serviced regularly (like most engines) then you may have corrosion built up between the upper bushing and steering bracket, and not allowing grease to flow between the shaft and bushing. The dry parts with the added engine thrust would have a tendency to bind. Have seen it more than a few times down here. Usually on larger engines but they basically are designed the same in that area.

OK, I'm pretty sure the motor has never seen salt water so I'll concentrate on trying to get some lube up to that upper portion of the pivot shaft that looks so dry. I'll post the outcome of that when I've either been successful or when I've given up. :shock:

If you can't, you probably know the drill. The gearcase has to come off. Depending on the engine, the powerhead can sometimes remain on the exhaust housing and be taken off the steering bracket as an assembly with the exhaust housing. Then remove the steering arm assembly from the steering bracket and whatever is going on should be right in front of you.

Just a thought. One thing that WD40 is actually very good at... is.. Dissolving old grease. I'd try dripping it in from the top. If it does loosen the dried grease, maybe you will be able to force new grease in.

I know some people think WD40 solves everything. I don't, but it might help here.

Yea Pappy, I'm trying to avoid thinking about having to do that.

Rich I gotta admit that it never crossed my mind that dried grease might be the reason I'm not getting the grease to flow to the top. I'll have to give that idea a try. Thanks.

There are many more aggressive grease cutters. Just figured you'd have WD40 on hand.

richg99

WD-40 actually restores rusted metal to its original form...that's what I heard.

Magically breaks down all the oxidation and returns the iron to its smelted configuration... it also will cure the common cold, bring peace to the middle east and halt aging all in one application...

onthewater102 said:

Magically breaks down all the oxidation and returns the iron to its smelted configuration... it also will cure the common cold, bring peace to the middle east and halt aging all in one application...

Click to expand...

You forgot to mention the strawberry cheesecake flavor.......... :---)