Yamaha 40 Cooling

[mdjames@iee.org.uk]

I have a '91 3 cylinder Yamaha 40Hp. I have a problem with steam in the exhaust. It has a new impellar, strong telltale, new thermostat and the plugs look fine. The head gets hot but not so hot I can't keep my hand on it. If I remove the thermostat the engine runs cool which I guess means the cooling jackets aren't clogged. I can't find the location of the popit valve in the Clymer manual or any earlier posts, could someone point me towards it please? Any other ideas gratefully received...

 

[Anymec]

Re: Yamaha 40 Cooling

There is no popit valve on that engine.<br />Here you have a picture of the cylinder head from a 50hp. (It's the same as the 40hp)<br /><br /> http://www.boats.net/yamaha/partsys...1991&*******=7af619ce4e2b2df3c941f0ba22c5176d

 

[mdjames@iee.org.uk]

Re: Yamaha 40 Cooling

Thanks for that The Fin. Back to the drawing board!