Tohatsu 25hp 2000 Gearbox neutral problem

[Commando C2]

I have a year 2000 2 stroke tohatsu 25hp.
Its the m25c model

I was out in the boat for about 2 hours and it developed a problem when trying to put into neutral from forward gear the prop was still spinning, i think it was reverse in fact.
Before you say it...no i hadnt knocked the gearshift into reverse.
I checked this.

i tilted the engine, when in neutral it was spinning slowly (boat was stationary) then when i put it into reverse it span faster as expected but when back in neutral it continued to revolve but at a slower rate.

Shortly before this we noticed the boat (SIB. Bombard c2) was feeling like it was getting a small boat wash wave from the side- the feeling that that would make when in the boat, but the water was dead calm and smooth.

I had flat hydrofoils on and the trim tab at its fullest to help combat torque steer.


its the gearbox issue that was most worrying. About 15 mins after stopping the engine i started it up and it went in to neutral as normal. We ran the boat for another 20mins and it worked fine then too.

Tookthe hydrofoils off and the sideways motion was reduced slightly but it never showed itself in the first 2 hours.

strange

any ideas on the gearbox thing would be helpful.
point of note-with engine off but in forward gear i can spin the prop with out it turning the engine over but in reverse it does turn the engine over if you spin it???!

is this normal?

sorry that was so long. tried to note all the relevant details.

 

[Commando C2]

Re: Tohatsu 25hp 2000 Gearbox neutral problem

heres a pic of some of the gearbox oil that i drained.
i changed it about 8 hours of running ago.

 

[TOHATSU GURU]

Re: Tohatsu 25hp 2000 Gearbox neutral problem

It's normal to get a slow revolution of the prop due to the force of the gear oil as it is moved through the lower unit. You could stop it with a feather....If it has more force than that, then the lower unit or control box has a boo boo.

 

[Commando C2]

Re: Tohatsu 25hp 2000 Gearbox neutral problem

shes a tiller steer so what kind of booboo might we be talking about?
it was strange that it did it after so long but makes me think the oil was overheating or something.
Water it was in was cold though.

 

[TOHATSU GURU]

Re: Tohatsu 25hp 2000 Gearbox neutral problem

On a tiller steer it would have to be an issue in the shift linkage on the engine...That's unlikely though.

 

[Commando C2]

Re: Tohatsu 25hp 2000 Gearbox neutral problem

engine seems to be ok now. used it again for 2 hours and no probs.
i did notice that one of the prop blades it bent about 5mm out of line of the other 2. this may have caused the sideways shake that i was getting.

 

[Commando C2]

Re: Tohatsu 25hp 2000 Gearbox neutral problem

one of the prop blades was bent, quite badly about 1 cm out of line from the other 2.
Have got a new prop now so should be ok i hope?!

One more thing....
would the engine still run if I swapped the spark plug leads over?
i have seen a pic of the same model for sale but the plug leads from the coil go to the opposite spark plugs that mine go to.

Do both cylinder fire together or alternatively on this engine?

 

[pvanv]

Re: Tohatsu 25hp 2000 Gearbox neutral problem

The 25C3 has a siamese coil. Both plugs fire at the same time. You can reverse plug wires and it makes no difference.

 

[Commando C2]

Re: Tohatsu 25hp 2000 Gearbox neutral problem

thanks for that info.
good to know for future reference.
regards

 

[jrs_diesel]

Re: Tohatsu 25hp 2000 Gearbox neutral problem

My 6 HP also turns the prop when its in neutral. It turns slowly in reverse. Like mentioned earlier it's due to the driveshaft (which is always turning when the engine is running) moving the gear oil around with enough force to turn the propshaft gears (in our case the reverse gear). Entirely normal from what I've learned here.

And as TG said, if the prop turning with any significant force or RPM, then something is odd in the gear case.

 

[Commando C2]

Re: Tohatsu 25hp 2000 Gearbox neutral problem

i guess if the prop does turn from the gear oil being moved around by the drive shaft it is a good way to tell that the gearbox is full with oil as if it was half empty the oil would have space to move into and not turn the prop shaft gently!

??