Tohatsu 3.5 runs in reverse! And sometimes forward!

[trickyseas]

Hi all,

I'm a new kid on the forum block and would appreciate any hints n tips as to why my Tohatsu 3.5 sometimes goes forwards and sometimes goes in reverse when the Shift lever is in the F (Forward) position. The lever has only 2 positions - N(Neutral) & F(Forward). Neutral always works. On the odd occasion when it decides to run in reverse, there's a nasty 'clunky' noise from the top-end.

Thanks.

 

[TOHATSU GURU]

Re: Tohatsu 3.5 runs in reverse! And sometimes forward!

Cause it's broke. No reverse on that model so unless the propeller can magically reverse it's blades....

 

[pvanv]

Re: Tohatsu 3.5 runs in reverse! And sometimes forward!

Yep. No reverse gear in that LU at all.

 

[trickyseas]

Re: Tohatsu 3.5 runs in reverse! And sometimes forward!

Cause it's broke. No reverse on that model so unless the propeller can magically reverse it's blades....

Thank you Guru for your most informative and eloquent reply.

 

[trickyseas]

Re: Tohatsu 3.5 runs in reverse! And sometimes forward!

Yep. No reverse gear in that LU at all.

Wrong - there is now!!!!

 

[Sea Rider]

Re: Tohatsu 3.5 runs in reverse! And sometimes forward!

Must be a special model or probably a 5 HP disguissed as 3.5; as stated by the gurus, has forward and neutral only...

Happy Boating

 

[TOHATSU GURU]

Re: Tohatsu 3.5 runs in reverse! And sometimes forward!

Thank you Guru for your most informative and eloquent reply.

Don't take offense when none is offered. You simply didn't know what you were taliking about.

 

[toyota3l]

Re: Tohatsu 3.5 runs in reverse! And sometimes forward!

You know, he might have a point , we had a chainsaw on the hire fleet that would start in reverse frequently ,it would bounce back on compression and of it would run quite happily! A 2-stroke will run in either direction, just look at direct reverse marine diesel engines, just change the ignition/injection timing! In chainsaw case, if my memory serves right, it was down to loose ignition module

 

[Sea Rider]

Re: Tohatsu 3.5 runs in reverse! And sometimes forward!

Sorry, 2 strokes are not diessel engines, besides that model has only neutral and forward, there is no reverse lever position or pinion on tail to reverse propeller spin, what you can do is while on forward gear rotate engine 180? and the engine will push in reverse a boat forward, that's all folks. Don't try to find 3 feet on a cat when has only 4.

Happy Boating

 

[TOHATSU GURU]

Re: Tohatsu 3.5 runs in reverse! And sometimes forward!

Its four feet on a cat with 3 feet

 

[dtj]

Re: Tohatsu 3.5 runs in reverse! And sometimes forward!

Sorry, 2 strokes are not diessel engines, besides that model has only neutral and forward, there is no reverse lever position or pinion on tail to reverse propeller spin, what you can do is while on forward gear rotate engine 180? and the engine will push in reverse a boat forward, that's all folks. Don't try to find 3 feet on a cat when has only 4.

Happy Boating

Wrong, this cat has 3 feet and it can dance;


"Two-stroke reversibility"


"Regular gasoline two-stroke engines will run backwards for short periods and under light load with little problem, and this has been used to provide a reversing facility in microcars, such as the Messerschmitt KR200, that lacked reverse gearing. Where the vehicle has electric starting, the motor will be turned off and restarted backwards by turning the key in the opposite direction. Two-stroke golf carts have used a similar kind of system. Traditional flywheel magnetos (using contact-breaker points, but no external coil) worked equally well in reverse because the cam controlling the points is symmetrical, breaking contact before TDC equally well whether running forwards or backwards. Reed-valve engines will run backwards just as well as piston-controlled porting, though rotary valve engines have asymmetrical inlet timing and will not run very well."


http://en.wikipedia.org/wiki/Two-stroke_engine#Two-stroke_reversibility


This doesnt solve the problem of the specific 3.5 Tohatsu running in reverse but is provided as more of information of interest...................Don

 

[TOHATSU GURU]

Re: Tohatsu 3.5 runs in reverse! And sometimes forward!

Yes, an engine can run backwards. I've seen it once or twice. But, that's not the case with this engine. The guy simply didn't know what he was talking about. When people are told that they are wrong they frequently want to shoot the messenger rather than to own up to their own stupidity. Internet forums allow the dumb to masquerade as the brilliant

 

[trickyseas]

Re: Tohatsu 3.5 runs in reverse! And sometimes forward!

The guy simply didn't know what he was talking about.

Oh - so I've owned the outboard for 7 years and now I don't know forward from backwards?

I removed the starter mechanism after starting the engine and - no great surprise - the engine was running anti-clockwise instead of clockwise
Well it's fixed Mr Guru no thanks to your wealth of knowledge - woodruff key had sheared so timing was all over the place.

Back to school Guru - The guy simply didn't know what he was talking about - unquote.

 

[Sea Rider]

Re: Tohatsu 3.5 runs in reverse! And sometimes forward!

woodruff key had sheared so timing was all over the place.QUOTE]

By woodruff key you mean the key that locks central drive shaft against magneto ? Just to know as always you lean something new, weird or extravagant, if corroded, sheared how did the magneto managed to still rotate clockwise at rope pull to move crank shaft & piston to start engine on ?

Happy Boating

 

[SteveRoss]

Re: Tohatsu 3.5 runs in reverse! And sometimes forward!

Nothing more depressing than what are supposed to be "common interest friends" calling each other names.... Hope this is the end of this thread.

 

[TOHATSU GURU]

Re: Tohatsu 3.5 runs in reverse! And sometimes forward!

Well apparently you do know and I was apparently too quick to judge you. Like I said, I have seen it happen once or twice....In 48 years. I work off of the likelihood of something occurring rather than the possibility of one out of 50,000. Sometimes it bites me.

 

[trickyseas]

Re: Tohatsu 3.5 runs in reverse! And sometimes forward!

Apology accepted

 

[trickyseas]

Re: Tohatsu 3.5 runs in reverse! And sometimes forward!

woodruff key had sheared so timing was all over the place.QUOTE]

By woodruff key you mean the key that locks central drive shaft against magneto ?

Yes - there is only one woodruff key on the crankshaft that drives the flywheel/ignition and the main stern drive.
Not sure how or why it sheared, but it only takes ~10-20 degrees of timing shift to mess up the rotation direction.
Must pack a few spare woodies with the shear pins!!

 

[trickyseas]

Re: Tohatsu 3.5 runs in reverse! And sometimes forward!

Nothing more depressing than what are supposed to be "common interest friends" calling each other names.... Hope this is the end of this thread.

Totally agree - I wasn't the instigator - ref "Internet forums allow the dumb to masquerade as the brilliant" from Guru. I'm very forgiving.

 

[TOHATSU GURU]

Re: Tohatsu 3.5 runs in reverse! And sometimes forward!

Actually my first response to you was correct. "No reverse, so unless it's magic" That wasn't meant in a nasty way. Your response to me was a little snide and that's what took this in a less than polite course. The fact is that your engine's problem was freaky. It was a lot more likely that you were a dunce than that you were accurately describing a fact. I was wrong. You were right. In the tens of thousands of tips that I give the law of averages says that I will occasionally be incorrect.

So the moral of this story is:

Sometimes even a Brit can be right