'92 Tohatsu M40C "stuck"

[sailhard]

This is a strange one.

Last fall this ( usually VERY reliable other than a few hiccups ) motor started giving me problems.

While runnning full throttle, the motor made some higher pitched noises and stopped short as if it were seized. ( motor weep holes were dribbling fine) I waited a while and restarted it but under load the same thing happened. the starter could not move the "stuck flywheel. If I let it sit for a bit, it would unstick itself and spin OK, idle fine but stick under load.

I brought it to an outboard guy last fall , and he said he replaced some parts in the fuel pump, ran it in his tank and said it was a great motor. I'm not sure what else he did, but it seemed to idle and run much smoother, but I never tested it out at sea.

So I finally got the boat out this season, it started right up great, I ran it at low speeds for about an hour and the damned thing stuck again. This time it would not come unstuck.

I removed the plugs and I can manually turn the flywheel backwards, but only turn forwards a few inches before sticking again. ( in any gear )

Any insights? I have a shop manual but it doesn't describe this symptom....

thanks.

 

[pvanv]

Re: '92 Tohatsu M40C "stuck"

Likely LU problem. Drop the LU and see if the powerhead is free. If so, you have isolated the problem.

 

[deejaycee_2000]

Re: '92 Tohatsu M40C "stuck"

Do a compression test, and post numbers here ....

 

[pvanv]

Re: '92 Tohatsu M40C "stuck"

Do a compression test, and post numbers here ....

Umm... Nope... Can't do that on a motor that is stuck... ;-(

 

[sailhard]

Re: '92 Tohatsu M40C "stuck"

Likely LU problem. Drop the LU and see if the powerhead is free. If so, you have isolated the problem.

Thanks for the replies, I was hoping someone had seen this exact problem before....she had great even compression last fall...

I didn't have a small enough drift to take out the shifter linkage spring pin to drop the LU.
I'm going to drop it off at the ( notoriously slow ) outboard guy's today to have another look, as he charged me $160 to look at the same problem last fall.

I hope it's not the lower unit...I priced some rebuilt units online and not sure if the motor is worth it, unless I can find a parts motor.

Is this lower unit the same as any other models?

Thanks again

 

[deejaycee_2000]

Re: '92 Tohatsu M40C "stuck"

Take out spark plugs and spray alot of WD40 into the cylinders let it sit a little and then try and pull it free it will come lose eventually and then do the compression test ... one of my motors dod the same thing ....

 

[pvanv]

Re: '92 Tohatsu M40C "stuck"

Take out spark plugs and spray alot of WD40 into the cylinders let it sit a little and then try and pull it free it will come lose eventually and then do the compression test ... one of my motors dod the same thing ....

DJC,

Since the motor is free-turning counterclockwise, but jams going forward (clockwise), I don't understand what WD40 might do for the powerhead. On the other hand, if there is a jam in the LU area, I can see where that would cause those symptoms.

 

[deejaycee_2000]

Re: '92 Tohatsu M40C "stuck"

It is just to free it in forward so that you can test the compression, you will most probably find that one of your cylinders has low or no compression and the piston and rings needs replacing .....

 

[sailhard]

Re: '92 Tohatsu M40C "stuck"

Problem may be solved, have not put the boat in yet.

My outboard guy said the LU was shot. He installed a "built" one for $450.

The other good news is that since we have broken down the last 3 times out, I finally have the green light to buy a new TLDI the next time it goes.

Thanks for the replys.