All tied up with 2stroke outboard

[newstick]

Well this is a great site.Since finding it have built small boat trailer well done all the cutting and grinding someone else welded up .However done some stick welding and learned something new,at a time when I needed diversion from health issues.So a big thank u to all who use this site .This is my first post so learning again.Well if any u guys worked on outboards an can help advise ,4hp2strokey yamaha 1995 overheating.I replaced impellar and housing ran good but put hood cover back on and instant overheated.Tell Tale got slow went dry.Now in process of stripping down tracing water circuit and poking wire to clear blockages.Found other relavent forums,but no site as good as this un.All replies welcome

 

[Tony]

Outboard

Hi,welcome to the forum. I have the workshop manuals on CD for the Yamaha engines as I do a lot of marine work. First thing to check is that you havn't nipped the tell-tale pipe when you put the lid back on.

Tony

 

[Tony]

Outboard

Forgot to say that if you want a copy of the manuals drop me a PM.

Tony

 

[mr mac]

have you run the engine dry at all? a impeller will get ruined so quick if run out of water


ian

 

[newstick]

Thanks to Tony Thanks to Mr Mac for replies,yes seconds out of water an running can ruin impellar an housing.New impeller an housing were fitted.,No hose pipe nipped when top cover put on,a strong tell tale coolant flow lets u know impeller is good,but water circulates and goes out via exhaust in any case.Under load or hood on overheating so looking for blockage must be old pieces of rubber impeller working round coolant channels.The engine is very good otherwise good starter.Hence stripping down,nothing showing round head or exhaust ports is it poss some block in feed pipe from impeller or at tell tale out.Could do with manual so pm Tony,I am new to using forums so please be patient an thanks for assistance.

 

[Thinphil]

Could be ignition timing has moved, 2 strokes are prone to overheat with incorrect timing.

 

[newstick]

This model not fitted with a thermostat.Later models have stat fitted in exhaust port area.

 

[newstick]

Due to easy starting I tend to discount timing at the moment.And the fact placing the hood on,restricting air cooling and placing emphasis on water coolant.All was ok to begin with,I think some old rubber then worked through system.Thanks Thinphil,I have lots to learn on this one,if I can stay cool not loose the rag an give up.

 

[the snooper]

could also be blocked up with salt if it doesnt get flushed out after using in salf water and if left the salt will expand and can push through thin places on the block.
i had this happen to an engine i got second hand stripped it down and was full of salt

 

[excossack]

Just a thought what about removing the impellor and back flush the system with a hose pipe? But not with the engine running.
Another thought, does the impellor have a key on the shaft to locate the impellor on so it spins as the shaft spins?