1997 MERCURY 75HP TILLER Clicking in "forward" gear only

It seems like about every 3 years I am posting on here about this lower unit ha.

Ill try to make this issue story quick *but prob won’t ha). It started when my motor seemed to be bouncing more than normal when running in some waves or even in idle the whole motor just seemed slightly loose on the boat. That wasn’t the case. I just needed to add grease to the lower zerk and everything tighten back up. Must have missed this zerk that last few years.

Anyway in the mean time I tightened these nuts (shown below) to try to remedy the issue. It didn’t (the grease I spoke of earlier did). And a few trips later I started having a noise while in forward that sounded in between a “clickclickcliclick” and a “chunkchunkchunkchunk” ha. If that makes sense lol. The higher revs the louder the noise go figure. When it started I was 10 miles from the launch and kinda limped it back but ended up blowing out the bearing carrier housing and obv the noise got worse and worse. I assumed that the bearing carrier was already cracked and I didn’t notice it so that was causing the initial noise. I got a new carrier and put the whole thing back together and everything lined up fine and seemed ok.

The LU gears had a little wear, but nothing that concerned me. Tested it last night and the noise is there but just slightly less. Also, I may still have those nuts (whatever they do ha) tightened wrong as my alignment on the shift pusher rod seems terribly off (see pic). Could that be causing this?

Anyone have and idea where to start (or know what those nuts do?) Reverse and neutral have no noise at all even when reved. Otherwise maybe I will have to bite my pride and send it to the shop. TIA!

The clicking noise you reference sounds like the lower unit isn’t fully shifting.. so, could be related to something with the shift cable adjustment or something else. One thing I noted in your picture, but can’t definitively say is a problem, is the angle your shift rod comes through the pivot to the lower unit.. I don’t recall them being sloped so hard, but don’t have another example to compare to.

marineman wrote:

One thing I noted in your picture, but can’t definitively say is a problem, is the angle your shift rod comes through the pivot to the lower unit.

I wonder about that angle too, marineman, do you know what the nuts I circled do? Could I have thrown off the shift rod and the complete shift alignment with tightening those? I thought I loosened them back the same I tightened them but I am unsure there. Should I tweak those?

Those nuts attach the lower unit (the lower part of the engine really) to the pivot bracket of the transom bracket; so, at a high level, keep the engine mounted to the bracket that is mounted to the transom. I don’t see any reason for them to be loose.

If you’re mechanically inclined (sounds like you are) I’d suggest disconnecting the shift cable at the linkage under the hood & manually shift it (may need someone to rotate the propeller slowly) and see if it’s “easy” to shift or if it binds / hangs up. If it’s “easy”, then I’d see if you can adjust your shift linkage to get rid of the clicking noise.

Double checking one thing… this clicking noise is only in one direction, right?

Looking at the lower gear housing schematic it would seem that when I tighten those nuts a couple rotations I could pull the lower unit towards the mount part of the outboard….but I don’t know if I should mess with those more.

marineman wrote:

Double checking one thing… this clicking noise is only in one direction, right?

Correct only in forward. I can disconnect the shift linkage I’ll give that a shot.

Marine, do you think I should tighten those nuts all the way down first just to remove that possible factor that they are bending the shift push pin?. They seem to be lock nuts but I know they are not all the way tight.

Also, in forward, in the garage, I can but it in gear and only spin the prop in one direction and that direction clicks but I am pretty certain that is normal as reverse does it the other way too

Evan!!!
it looks like the shift shaft is stacked on top of where it should be coupled and is now bent but somehow operational??.
either that or your drive housing mounts are that shot and in need of immediate if not sooner replacement.

how far is Hastings from Kellogg Ia??? if ya need help,just send a smoke signal,ah,I keep forgetting this is 2020,shoot me a PM.

Evan Pheneger wrote:

Also, in forward, in the garage, I can but it in gear and only spin the prop in one direction and that direction clicks but I am pretty certain that is normal as reverse does it the other way too

That’s normal… unrelated to your current issue.

Iowaboy1 wrote:

either that or your drive housing mounts are that shot and in need of immediate if not sooner replacement.

I’m wondering if this isn’t the issue if your shift linkage adjustments check out

I thought I would follow up in case anyone else runs into this issue on the world wide web. I (with help) have rebuild the lower unit on the merc by replacing the pinon gear and forward gear and a bunch of bearings. Fixed the issue but it was quite a chore.

I want to give a huge shout out to two peps. The first is IowaBoy (Sheldon) who posted above and who many of you know. With all the political crap and even sometimes arguing right here on this forum amongst sportsman its great to know there are still MANY people like Sheldon. He took the time to chat with me a few times and give me the push to continue my rebuild when I was having a ton of issues pulling my drive shaft. He went as far to offer his place to stay at if I wanted to come crank on the LU at his place. Quite a generous offer and your help and care you showed will definitely be paid forward.

The other is a long time old coworker and fishing friend Greg Krull (also on this forum). He build me a genius homemade drive shaft puller when the shaft was stuck on the pinon in the LU housing. All this just to have my boat ready to compete directly against him in the up coming Saugerama Tournament! What a guy!

I also believe I figured out my issue on what caused all this. When I took apart the LU to troubleshoot then change the drive shaft seals this spring I lost a few cam follower ball bearings (2 of the 3). I thought it fell on the ground as I couldn’t find it in the LU. I replaced them and I completely forgot about it till the LU was finally all apart and there it was in front of the forward gear. They did some damage in there! SMH what an idiot

Here are some pics of the adventure.

Glad you got it figured out!