1991 force 150 siezed up? Help please!

[Captain Jager]

Ok, one week ago I was flying down the river and all of a sudden she stalls on me. I found the the bendix was staying engaged on the fly wheel. I'm assuming it over heated the starter swelled and up stalled the engine. it restarted shortly after. ran fined then stalled again. a fellow boater towed us in. after having the starter rebuilt I tried it again tonight. it just clunks, wont spin. removed plugs still nothing? even wrapped a rope on the flywheel, pulling with all my might it wont budge. how can it have ran so great on minute and be seized the next? I heard nothing out of line? suggestions please???!!!!

 

[Frank Acampora]

Re: 1991 force 150 siezed up? Help please!

Sorry to say but at this point you need to remove the head and look at the pistons. Very frequently outboards will suffer "silent damage" because they are so noisy you do not hear anything happening.

Also, unfortunately, these early 150 engines were known to break crankshafts. That is also something you would want to check if all the pistons look to be in good condition.

 

[pnwboat]

Re: 1991 force 150 siezed up? Help please!

Drop the lower unit. If that frees it up, then the motor is fine and the problem is in the lower unit.

If it is the lower unit, there's a good chance that the upper drive shaft bearing has seized. The last 3 lower units that have the two piece drive shafts that I've worked on had that bearing seized. I worked with another Forum member here and he had the exact same problem as you. He had a 150HP motor too. Replaced the bearing and a seal kit and he's back on the water.

 

[Captain Jager]

Re: 1991 force 150 siezed up? Help please!

Drop the lower unit. If that frees it up, then the motor is fine and the problem is in the lower unit.

If it is the lower unit, there's a good chance that the upper drive shaft bearing has seized. The last 3 lower units that have the two piece drive shafts that I've worked on had that bearing seized. I worked with another Forum member here and he had the exact same problem as you. He had a 150HP motor too. Replaced the bearing and a seal kit and he's back on the water.

I think you nailed it buddy!! I pulle dthe lower and the motor spins fine. the lower barely turns but I don't see any metal in the oil that I drained so I assume that's a good sign as well. Any one have a diagram or write up on rebuilding the lower unit?

 

[jerryjerry05]

Re: 1991 force 150 siezed up? Help please!

Look on e-bay LOTS of manuals for the 150.
The factory manual is the only way to go.
I bought one,with shipping $12

 

[pnwboat]

Re: 1991 force 150 siezed up? Help please!

You need some special tools to get the spanner nuts that hold the upper bearing and the lower bearing spool assy. off. Each spanner nut requires a different size spanner nut removal tool. Even if you do have the tools, you may need a hydraulic press to remove/install the replacement upper bearing race. If you don't have the tools, then you may have to look for a used unit.