4 HP Tohatsu outboard thermostat

[boatmike]

The basic question is "where the merry hell is it? The main cylinder has a 5 bolt fixing on the head with a central spark plug. I can see no other access to waterways and no obvious access to the thermostat. I am of course assuming there is one...... Rather than just strip it down willy nilly does anyone know where the **** thing is?

 

[VicS]

You don't say what year, if that makes any difference, but you will be able to see it in the relevant cylinder head diagram in the parts lists at Parts Catalog : , Reliable Source of Nissan Tohatsu Boat Marine Genuine OEM Parts

 

[boatmike]

Actually Vic its a 2005 M4C 2 stroke and isn't on that list. Its in generally excellent condition but has been in storage for a long time. Starts OK. Runs OK but no water going through although impellor looks OK so the next thing to check would be thermostat ( if I could find the booger) I think its either a blocked thermostat (if it has one) or clogged up waterways. As it's in generally good nick otherwise I suppose its worth a total strip down and internal clean. Strange though, I had expected to find an easy access plate in the cylinder body somewhere but there's nothing. Have never seen a motor without a thermostat but I guess there is a first time for everything......

 

[VicS]

Actually Vic its a 2005 M4C 2 stroke and isn't on that list. Its in generally excellent condition but has been in storage for a long time. Starts OK. Runs OK but no water going through although impellor looks OK so the next thing to check would be thermostat ( if I could find the booger) I think its either a blocked thermostat (if it has one) or clogged up waterways. As it's in generally good nick otherwise I suppose its worth a total strip down and internal clean. Strange though, I had expected to find an easy access plate in the cylinder body somewhere but there's nothing. Have never seen a motor without a thermostat but I guess there is a first time for everything......

Ah.
Look at the list for 5hp models and you will find that the M4C is listed with the M5B
I can't see a thermostat

 

[boatmike]

Just for the record Vic, you are correct. In case anyone else tries it the M4C Tohatsu has NO thermostat at all. I have stripped it right down and cleaned all the waterways and await delivery of parts before reassembly but there is definitely no thermostat. Also be aware if anyone else tries it that the cylinder head bolts are not high tensile and were rusted in. 2 broke off and I have had to drill them out and re tap the 8mm holes. Will replace bolts with HT steel on rebuild.