Tohatsu 3.5HP 2 Stroke Too. Coolant water.

[davidpbo]

Like Jimminy I read in this forum and in various mags recommendations for the Tohatsu 3.5Hp 2 stroke.

I bought a 2 year old version recently which starts and runs fine, it does lack some of the features of the 4Hp Yamaha it is to replace. It is possible to see why the Yam costs more but the Tohatsu is considerably lighter and I hope will fufill its function as power source to our small tender admirably.

Two questions.

1) Tested in a drum, the coolant water jet is very slow, a drop every second or so and does not seem to get much faster after running for a while. The engine (crankcase and pressure release cap) is cool to touch.

I read in a previous post today or yesterday regardinga Suzuki that it was thought that running it in a tank may be contributing to the poor flow.

Do I have a problem or not? I don't think so but just asking.

2) the external plastic case splits down the middle. Does this cause any problems with water ingress from rain and spray.

Otherwise very pleased with the engine.

TIA

David

 

[Honey]

I have just bought a new one of these engines and find that when running in a tank I get a steady dribble from the tell tale but, as with most outboards, the water intake is at the front and therefore partly obscured when running in a tank! Try it on your tender and you should get a steady (but not strong) stream from the tell tale.
With regards to the case design I have had no problems yet but mine is only one week old with about 5 hours use so far.

 

[mikejames]

The coolant telltale should be a thin stream of water.

The split in the casing shouldnt matter too much as the engine is mostly painted inside the casing and there is always a film of oil on the ferrous parts of the engine. The hose clip on the fuel tap will rust as it touches the case of the engine and keeps a little drop of water there.

I now have one of these replacing a Tohatsu-built Evinrude which warped its cylinder head after waterways clogged up to the point where the telltale dripped. However it was hard to start as a result as water seeped onto the plug when it was cold. That was after about 6 years of use, I probably did not flush the engine enough after use.

 

[Rick]

Should be a steady stream of water from the tell-tale. My dealer says the impellor should be changed annually, so that's where I'd start, but I'd say you definitely need more water coming from the tell-tale. Try pushing a piece of wire up and see if any crud is there to partially reduce the water flow.

 

[davidpbo]

[ QUOTE ]
Should be a steady stream of water from the tell-tale.

[/ QUOTE ]


Is there a thermostat on the engine?
So I don't go around the houses, how do I gain access to the impeller, do I have to remove the bottom of the OB leg?

Thanks

David

 

[rob2]

My engine stopped pumping cooling water whilst en route to the mooring the other day. Lots of smoke as we melted the steering bushes! I dropped the bottom of the leg and checked the impeller, which sits on the bottom of the drive shaft, it was fine. Blew up the pipe and dislodged some salt crystals and now its going great guns.

 

[m1taylor]

Why don't they design bigger water channels in the first place? This is what I can't understand about modern small outboards. Take an old design for instance - the seagull 40plus - the water channels are huge by comparison and the impellor indestructable.

 

[Rivers & creeks]

Run this engine every week in a tank to flush after the run to and from the mooring. Even in a small dustbin we get a healthy stream of water from the tell tale so I would suspect that there is a problem with crud in the pipe. As the head is cold it suggests that the cooling system is working well but the smaller bore pipe to the tell tale is mostly blocked, just needs a needle usually to unblock.

 

[yoda]

Remove the cowling and remove the rubber tell tale pipe from the engine. Blow the pipe through and use a small piece of copper wire to prod up the exit nipple. This often clears minor blockages which seem to occour in these areas.

Yoda

 

[davidpbo]

[ QUOTE ]
Remove the cowling and remove the rubber tell tale pipe from the engine. Blow the pipe through and use a small piece of copper wire to prod up the exit nipple. This often clears minor blockages which seem to occour in these areas.

Yoda

[/ QUOTE ]

Wish I had done this first as there was some minor deposit.
Inspected impeller which seems OK but will replace anyway,

Having inspected and poked through I think the minimal salt deposits would have been flushed through if the impeller was working properly.

Am I right in thinking the water pipe out of the engine is a tell tale and that the bulk of the cooling water goes down the leg? It looks like it from the engine block channels.

There are two holes in the leg just below the lower support which output water in neutral but not in gear. Are these exhaust breather holes?.

 

[davidpbo]

Thanks for everyone's advice. Engine now pumping water fine , know that the accessible water channels are clear and that is has a new impeller.

David

 

[Oldhand]

[ QUOTE ]
Should be a steady stream of water from the tell-tale. My dealer says the impellor should be changed annually, so that's where I'd start, but I'd say you definitely need more water coming from the tell-tale. Try pushing a piece of wire up and see if any crud is there to partially reduce the water flow.

[/ QUOTE ]

If there is no sign of steam coming out of the tell-tale hose then the engine is still being cooled satisfatorily, thus the impeller is fine and the tell-tale is the problem. The latter has a very small aperture in the cylinder block which can easily be constricted by crud. Attach a car tyre foot pump to the end of the tell-tale hose (it happens to fit perfectly) and give it a few sharp pumps to blow the crud away. Test run the engine immediately after and continuous flow from the tell-tale should resume. /forums/images/graemlins/smile.gif