1990 Force 150 outboard flywheel problem

[Uncle Nanny]

Help!! I recently purchased a Ranger bass boat with a 1990 Force 150 outboard motor. I am not familiar with these motors ;most of my past experiences are with Johnson and Evinrude.However,<br />here I am with an engine that would barely turn ouer but I was getting spark at the plugs. Further inspection I found the negative battery cable ROASTED. After checking the starter; It was ,too.<br />I replaced the starter and still the motor would only turn about one cylinder at a time. Being used to working on car engines I suspected a timing problem. Sure enough the flywheel key was sheared. I purchased a new key and at the marine dealer's suggestion to torque it to 120 to 150 ft/lbs. Being leary, I chose the 120 ft/lbs with a torque wrench and not my impact gun as suggested.<br />I had to wedge a board between the prop and put it in gear in order to tighten it. Put motor in tank started up and ran fine , no problem. Took boat to lake, started making a grinding noise at start-up and kept slipping out of gear. Shut down and brought home. Found flywheel loose and key loose inside. WHY IS THIS HAPPENING??? I understand that the key is case harden steel. How did this key sheer the first time? It was like this when I made the purchase. One blade on the prop was slightly bent, but not that I would think it would sheer the key instead of the rubber hub in the prop.I purchased this boat and motor from a man that had it for over a year and could not get it to run. What little bit I ran it it sounded great; until the flywheel came loose again. The inside of the flywheel key area is a little wollered out ever so slightly. The shaft end of the keyway does not appear to be hurt.Is there suppose to be a lock washer under the flywheel nut ? ANY SUGGESTIONS ,ANYONE?

 

[y-knot]

Re: 1990 Force 150 outboard flywheel problem

I pulled the Flywheel off my 125 last year. It should have a taper fit between the flywheel and the shaft. When I replaced mine, I noticed you could knock the key out as you lowered the flywheel. It took me several times to get the key and flywheel in position at the same time. I also checked the Seloc manual for the Torque on that nut. It calls for 90 Ft-LB for a 1990, 150HP. The 1991 plus models call for 130 Ft-lb. If you think the key was in position after you tightened the flywheel down, I would check the fit between the flywheel and they shaft. You may have a burr or some other crud that is keeping them from seating fully.<br /><br />One last thought. My key is half moon shaped. It fits in the shaft, slot which is also half moon shaped. They key is kept from vibrating out by the half moon fitting in the same shape slot in the shaft. If you think it is vibrating out, you may check the shape of the slot vs the key you have, ensuring the key is captured when installed. <br /><br />Good Luck.