50 h.p. force with a "clunk"

Zaxxon II · Oct 30, 2003

I just got an 89 Force 50h.p. It runs fine on a 15ft Maxum. It recently had some lower unit work done and the mechanic said he shimmed something in the lower nose area. The previous owner said the bearings and race were good as well as all gears were fine. When I took the boat out it had a loud "clunk" in the lower unit upon acceleration. It only did it once with each acceleration, rather fast or steady. One other time it clunked when the throttle was held at less than 1/2 for a while. any ideas where to start.

The Marine Doctor · Oct 30, 2003

Re: 50 h.p. force with a "clunk"

There are no shims in a 50hp Force gearcase. The style you have anyway. There are standard spacers that are used in all models. I suspect a broken tooth on the gears or its jumping out of gear. TMD

St. Johns River Rat · Oct 30, 2003

Re: 50 h.p. force with a "clunk"

I have a 90' 50 hp that did the EXACT same thing. Lower unit torn down and inspected. Teeth, gears, every part looked pristine. Put back together. Same problem upon acceleration, loud clunk. Finally got a hold of an old time mechanic who told us that Force motors are notorious for this problem..... coming out of gear. Solution was to change the travel of the engagement so that the clutch dog was further forward in the travel. Works fine except that you have to slightly pull the throttle/engagement lever into reverse to get the prop to stop. No big deal BTW. Not a fix, but allows me to use the boat. Been running it this way for a year. Problem has not resurrected itself. Rebuilding/replacing the lower was unit would have been cost prohibitive at its age. Until it totally craps out.... this is how I will run it. Try adjusting the travel first, if that get rid of the clunk!(and I believe it will)you can decide what to do about the comfort level using the engine. We chased this problem for about one year thinking it was ignition related. Good luck!!!! Rat

Zaxxon II · Nov 1, 2003

Re: 50 h.p. force with a "clunk"

Thanks Rat. I suspected it might be something simple like the shift adjustment (at least I hoped). The manual I have says to mark the shift rod in forward and then in reverse and then set it in the middle of those marks. Do you have any further specifics on the adjustment or do I just go further towards forward until the clunk goes away? Also you said I will need to shift into reverse to stop the prop. Do you mean momentarily and then into neutral, and does this affect neutral at all?

The Marine Doctor · Nov 1, 2003

Re: 50 h.p. force with a "clunk"

If the shifter is set up properly, there should be no need to have to shift partially into Rev to gain neutral. TMD

force01 · Nov 1, 2003

Re: 50 h.p. force with a "clunk"

Sounds like you are jumping out of gear. If everthing is adjusted right the gear box will work fine. It is not a common problem with forces to jump out of gear. Any outboard gear box will jump out of gear if it not set up correctly. Once you have a clutch dog and a forward gear that have rounded themselves off from jumping, at that point you will never get the gear box to stay in forward gear without jumping. Try to adjust it like this: advance your control box to full throttle, rotate your prop until you feel it lock in, take your handle and go to neutral and back to full blast, while moving the prop back and forth hitting each side of the clutch adjust your shift adjustment nut on the side of your motor until you feel a slight drag on the prop then lock the lock nut down and recheck. Dont put too much drag or else it will not go into neutral like it is supposed to. good luck, bret If you need further assistance please email me @ forcepower01@yahoo.com. thanks,Bret

Zaxxon II · Nov 2, 2003

Re: 50 h.p. force with a "clunk"

Hey force 01 or TMD, or anyone who knows: I have been trying to adjust the shift linkage on my 89 50hp Force. The manual is fairly clear but the shift cable lock clamp is hard to get to. I was wondering if it can be adjusted by turning the connecting link (it's like a closeline tightener) on the shift rod itself. Also the instructions I got from force 01 said to spin the prop until I felt resistance as it goes into gear. My prop won't turn freely even in neutral. This doesn't sound right. Any advice? Thanks

The Marine Doctor · Nov 2, 2003

Re: 50 h.p. force with a "clunk"

If you are refering to the connection midway down the leg....you can and should adjust there. TMD

St. Johns River Rat · Nov 2, 2003

Re: 50 h.p. force with a "clunk"

Not to step on the knowlegeable toes of TMD and/or Force 1, my lower unit was inspected by two well trained and respected mechanics. Both put it back together and problem remained. ALL the gears were throughly inspected and found to be pristine. No teeth missing, no cracks, no visible problems at all. Matter of fact, the unit gears looked brand new. Now on paper, when machine parts are put back together, they should work flawlessly. But this ain't paper or theory. Reality is this, only solution to my problem was adjusting the linkage forward and tinkering with the reverse to put it back to neutral. Or to put new gears in and take a leap of faith. The old mechanic in Alabama who helped me with this problem made a strong case advising me against such a move. So I'm not questioning your training, just that this may be one of those rare exceptions to the rule. Just my humble opinion. Thanks for listening. Rat BTW, TMD and Force 1 thank you hundred times over for your support on this website and forum. Untold help has been given and appreciated.

The Marine Doctor · Nov 3, 2003

Re: 50 h.p. force with a "clunk"

What was the condition of the shifter yoke? Is there slop in the control box? Bushings worn out on the engine? Was the shifter seal installed with the correct tool? TMD

St. Johns River Rat · Nov 3, 2003

Re: 50 h.p. force with a "clunk"

Control box tight at a tick, correct tools used, shifter yoke looked brand new. Now the bushings in the engine...... what bushings are you referring to? We focused on the lower unit and connection mid-point of the leg. If we needed to tear apart the powerhead... that was not done. I have a manual from SEALOC. I can look up what you may very well have stumbled on to. Again, your expertise, my forced knowledge to learn on the job. So to speak. Neither mechanic made mention of any bushings. Let me hear about what you think. Thanks, Rat

The Marine Doctor · Nov 3, 2003

Re: 50 h.p. force with a "clunk"

The bushings are located in the under the carb area. They are plastic and prone to wear out. If this happens...we get slop, or loose shifting. TMD

50 h.p. force with a "clunk"

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