Tohatsu 3.5 Two Stroke issue.

[rogerowen]

We have acquired this engine and it was fine first time out - just a short trip from slipway to our swinging mooring (about 3/4 of a mile), and back again, all fine. Cleaned the motor in fresh water in a wheelie bin without a problem. Then, went to use it 2 weeks later and it was seized solid, could nor pull start at all. Have un-seized with 3 in one oil down the bores and turning gently until moving relatively smoothly (still a bit 'dry' sounding). Back to the wheelie bin, and it started first time, runs fine at tock-over, water coming out of the drain pipe but not getting past Luke warm. Engine block is warm to the touch but not HOT. Open up the throttle, runs for a bit - then dies, and will not re-start for a minute or so. I'm running the engine with the cover off - but it sounds mechanically 'dry' when running, quite noisy. I've had a look down the plug hole with an endoscope and can't see anything obvious. I've increased the fuel oil mix from the recommended 50:1. As the block doesn't seem to be getting excessively hot, I'm not sure if this is seizure, but the 'Dry' running noise might point to some mechanical issue. Anyone experienced the same issue?

 

[Kelpie]

Is there smoke, and if so, what colour?

 

[rogerowen]

Yes, white smoke, wonder if due to my increasing the oil in the fuel mix.

 

[greeny]

We have acquired this engine and it was fine first time out - just a short trip from slipway to our swinging mooring (about 3/4 of a mile), and back again, all fine. Cleaned the motor in fresh water in a wheelie bin without a problem. Then, went to use it 2 weeks later and it was seized solid, could nor pull start at all. Have un-seized with 3 in one oil down the bores and turning gently until moving relatively smoothly (still a bit 'dry' sounding). Back to the wheelie bin, and it started first time, runs fine at tock-over, water coming out of the drain pipe but not getting past Luke warm. Engine block is warm to the touch but not HOT. Open up the throttle, runs for a bit - then dies, and will not re-start for a minute or so. I'm running the engine with the cover off - but it sounds mechanically 'dry' when running, quite noisy. I've had a look down the plug hole with an endoscope and can't see anything obvious. I've increased the fuel oil mix from the recommended 50:1. As the block doesn't seem to be getting excessively hot, I'm not sure if this is seizure, but the 'Dry' running noise might point to some mechanical issue. Anyone experienced the same issue?

This bit of the symptoms sounds like the float chamber valve gunged up not letting much fuel through. When you increased the revs the float chamber emptied and then takes a while to get a level of fuel back in it before it will restart. On tickover the usage is much lower so maybe enough is getting past the valve to keep it going just. Maybe running on a weak mixture because of this blockage and producing white smoke. As for it not getting up to temperature, check the thermostat. That may be seized up as well allowing full water flow through the engine all the time. What do you know about the history of the engine. Maybe its been stood a long time and carb was not drained and waterways were not rinsed out before hand

 

[C08]

You need to take off the float chamber and clean it out and then have a look at the float needle. Over years they tend to gung up and acquire some corrosion. I have one of these and the only problem I have had is a corroded float needle. I woulsd not worry about the temperature of the engine, my telltale flow has always been lukewarm from new, now 17 years old.

 

[Graham376]

Seizing after being left for some time can be the shaft seals allowing water into the bottom crank bearing, which seizes. Happened to our last 9.8 2 stroke.

 

[ithet]

Is there oil in the gearbox housing (lower leg)? I would change it anyway on an old engine. The carb float chamber probably needs cleaning out, they always need cleaning out!

 

[dod]

We have acquired this engine and it was fine first time out - just a short trip from slipway to our swinging mooring (about 3/4 of a mile), and back again, all fine. Cleaned the motor in fresh water in a wheelie bin without a problem. Then, went to use it 2 weeks later and it was seized solid, could nor pull start at all. Have un-seized with 3 in one oil down the bores and turning gently until moving relatively smoothly (still a bit 'dry' sounding). Back to the wheelie bin, and it started first time, runs fine at tock-over, water coming out of the drain pipe but not getting past Luke warm. Engine block is warm to the touch but not HOT. Open up the throttle, runs for a bit - then dies, and will not re-start for a minute or so. I'm running the engine with the cover off - but it sounds mechanically 'dry' when running, quite noisy. I've had a look down the plug hole with an endoscope and can't see anything obvious. I've increased the fuel oil mix from the recommended 50:1. As the block doesn't seem to be getting excessively hot, I'm not sure if this is seizure, but the 'Dry' running noise might point to some mechanical issue. Anyone experienced the same issue?

Hi had one of these since 2006.(still going) Here is my tuppence worth! Since you have sorted the seizure problem you are looking at fuel problem now. These are notorious for clogged jets, there are 2. The mix ratio is critical and too much oil will clog up the carb , so make sure the mix is correct. check the tank and make sure there is no debris or gundge,(best give it a clean as it is second hand). Now remove the carb. and then the fuel reservoir (take care with the gasket or you will need to make a new one). Clean it and check the jets. You can clear them using a cocktail stick or something, then blow through and check that they are clear. Put it all together and test. Finally you may need to adjust the timimg screw for idling. Good luck.