need help, lower unit issues

[tjakobic]

So last night a couple buddies and I were replacing the impeller on my 1977 85hp mariner outboard. After we put it all back together and started it up the motor was in gear going forward while the controls were in neutral. Also the stream is not much better from the new impeller. I tried using some weed Wacker cable to push out anything that may be stuck. Can anyone give me some advise?

 

[Chinewalker]

The shift issue is a common one. It's possible for the shift rod to go past forward in the lower unit, such that when it is aligned, even if the upper rod moves to neutral, the lower is still in forward. You need to align the shifter so that upper and lower shift rods are properly aligned. I prefer to reassemble with both top and bottom in the neutral position (prop spinning freely, feel for the detents in the cam).

 

[Chris1956]

It is hard to eyeball the telltale stream to determine the quality of the cooling. A water pressure gauge would show maybe 5PSI at idle, and maybe 15PSI at high speed, with a new impeller.

 

[tjakobic]

no matter how I spin the gear shaft the propeller clicks to go forward and will not go in reverse at all.

 

[Texasmark]

no matter how I spin the gear shaft the propeller clicks to go forward and will not go in reverse at all.

Clicking when rotating the prop CW as viewed from the rear is normal for F gear. Attempting to turn the prop CCW in F gear meets resistance and won't turn till the crankshaft turns also. In N, as walker said, prop spins freely.

Drop your lower unit down enough to get at the splined shifter shaft. Push the rod coming down from the powerhead up and off the shaft. Set your remote to N and wiggle it to ensure it's in the center of it's range. with a pair of pliers or a visegrip plier, carefully rotate the splined shifter shaft back and forth till you find 3 detent positions. There will be a little cam to spring loaded cam follower resistance but you don't force it. It will move if you are turning in a direction where it can. Set it in the center of the 3 positions. Set the shifter shaft back down on the shaft and push your LU back up and button her up.

Where were you and how were you cooling the engine when you made the comment about the tell tale result? On that engine the hose connects to the exhaust manifold and water is available as soon as the pump gets water up there. On muffs at idle with adequate water supply, the stream should be solid and strong, increasing in intensity as you advance rpms. You might take it loose at the hose barb coming off the exhaust manifold and blow through the hose to check it.

 

[tjakobic]

OK I'm am trying to understand everything u just said. Does it matter that when I turn the gear shafts on the top of the lower unit nothing changes in the way the propeller is clicking forward and not going reverse at all. At no point the propeller will spin freely "neutral"

 

[tjakobic]

And my drive shafts just spins, it doesn't go up and down from the powerhead

 

[tjakobic]

We noticed that it spins when u move the control handle too, no up and down movement

 

[Texasmark]

Maybe you are farther back in year model than I anticipated and your linkage isn't as I expected and isn't like Mercury has had for 50 years. I have not seen your engine. I am answering on the fact that Mercury picked up the badge as a Japanese built Mercury and painted them silver rather than black and put a slightly different looking cowling on them.

Chinewalker is talking about upper and lower rods and getting the linkage right and that doesn't sound like the '77 85 Merc I had.

When you remove the lower unit is there a 3/8" diameter splined shaft about 1" tall sticking up near the front end of it? Can you twist it such that it stops in 3 adjacent positions only?

 

[tjakobic]

Yes that is what it looks like. The 1" spline shafts spins but there isn't any clicking into different positions.

 

[tjakobic]

Also when we turned the prop the crank shafts does not turn just moves a tinny bit and goes right back where it was.

 

[Chinewalker]

Does the splined shaft on the top of the lower unit freely spin a full 360 degrees? If that's the case, then you'll have to dig further, as that means someone has pulled that shaft out of the unit at some point. The spring loaded plunger inside the propshaft will push the cam out of the way if the shift shaft is pulled out of the lower unit. It is impossible to put the shaft back in with the lower unit together and it must be pulled apart to put the shaft back in.

If the splined shaft (shift shaft) does NOT spin a full 360, then you need to put some torque on it to turn it against that spring in the propshaft, mentioned previously. It's a hefty spring and takes some beef to push the cam & pin against it. As Tex mentioned, use pliers or Vice grips, taking care to avoid marking the splines, to turn the shaft against the spring tension.

 

[tjakobic]

Here is what I am working with...

 

[tjakobic]

 

[tjakobic]

I can spin the shift shafts 360 but then it click in and will only turn 180 again

 

[tjakobic]

The prop turns reverse with some pressure and clicks forward as long as I don't have the pump housing on too tight

 

[tjakobic]

Started the motor up and still stuck in forward. If I put it in reverse it still goes forward. If revs up both ways.

 

[Texasmark]

You are getting into things that really need someone there to see and feel. Chine made a valid point and makes a lot of sense in your not being able to find the 3 cam detents. The other end of the shaft you show in pic no 1 is splined also and slips into the cam which is a piece of metal with 3 detents each a different distance from the pivot point. If that shaft has been pulled out you no longer can do that. The prop shaft has a sliding gear (clutch dog) that moves from the back of F gear for cam position 1, to mid position where it contacts neither F or R and you are in N, the prop spins freely with no regard for what the engine is doing, and the 3rd position is R where the dog locks into R gear with square cogs and pins so it is locked in both directions and does not click like in F gear's "overrun clutch".

The action of the spring loaded pin that follows in the cam slots is such that it and the clutch dog will go forward if no cam is present which will lock the prop shaft to F gear, meaning that from the rear looking forward, you can spin the prop CW with it clicking (overrun clutch active) and the drive shaft up to the engine does not move, to CCW where it offers high resistance and if you get it to move in that direction the crankshaft moves too.

Do this for me. Since you have the LU dropped, grasp the drive shaft....the shaft that goes up to the powerhead with a vise grip or pair of pliers and turn it CW. What does the prop do when you do that? We'll go from there. I just don't understand your comments about things other than the shifter shafts which I think we have concluded that the shaft to cam need attention and just looking to see what else may be wrong.

I'll wait.

 

[racerone]

When you turn the shift shaft counter clockwise it will be easy.----That is untill you actually have to move the clutch dog.----That clutch dog has a strong spring on it,.--So use a vicegrip on it to continue turning till you do in fact get nuetral !!!

 

[Texasmark]

When you turn the shift shaft counter clockwise it will be easy.----That is untill you actually have to move the clutch dog.----That clutch dog has a strong spring on it,.--So use a vicegrip on it to continue turning till you do in fact get nuetral !!!

Something we aren't understanding here and I think Chinewalker nailed it. Someone pulled the shift shaft up and out of the shifter cam slot. With no (cam) pressure against it, the spring pushed the dog and the cam follower all the way forward and into the rear of F gear. That's verified by his getting the over run clutch clicking from F gear when he rotates the prop CW.

When he is talking about 180 and 360 rotations on the shift shaft with no detents felt and can't change the gearing from F, he apparently is disconnected where the shaft enters the cam as walker said. In his first picture it doesn't appear that the shift shaft is sticking out all that far, but the cam isn't what, 1/4" thick, so it wouldn't take much movement to pull it out. Can't measure very well from the angle of the shot. Been a long time since I had one out and don't remember how hard it was to stab it. However with the follower spring pushing on the follower, it might be impossible to luck into a successful blind stab.