Yamaha 2A outboard - how much cooling water should I see?

[labougie]

Just acquired a 1973 Yamaha 2hp which seems to run fine. My only query is the amount of cooling water I can see coming out. According to the manual, it doesn't have a jet of water coming out vertically below the engine, rather it has four "pilot outlets" in the leg, which are sending out only the occasional spit of water. Should I have a good flow of water from these holes? There also seems to be some pressure escaping from the pilot outlets as well as a little water. Have I got a crusted up cooling system? Have I got a head gasket problem? Thanks in advance.

 

[VicS]

Those holes in the leg are exhaust back pressure relief ports.

Since the cooling water is discharged into the exhaust you will see a few droplets ,a mist or a spray being blown from there but the bulk of the cooling water leaves via the main underwater exhaust outlet.

If it starts and runs well and the plug looks normal there is no reason to suspect the head gasket.

If the cooling is good you should be able to touch the powerhead and maintain contact for a few seconds. If it is to hot to do that , if a splash of water sizzles and boils, if the paint is discolouring or if you see steam from the relief ports it is overheating.

It If you have any doubts it would be wise to renew the waterpump impeller.

Also before you use it check the gearcase oil for level and for signs of water ingress or even change it.

 

[Lakesailor]

I've found that those sorts of relief ports seem not to pass much water until you put your hand behind them, when your hand will become covered in rather oily water which hopefully will be fairly cool to the touch.

 

[labougie]

Many thanks for the input. I had the gearbox off today to check the impellor which looks OK visually - the little bobbles on the ends of the vanes are all intact and nothing looks too cludgy. With the gearbox off, I had access to the plastic pipe which carries the cooling water up to the engine from the impellor and I squirted mains pressure water up the pipe to find that 95% of it came back down the exhaust tube - it only dribbled out of the pilot outlets. I'll use the hand on (cylinder) head test next time I have it running to verify that it's not overheating and then cross it off the worry list. Plug is a bit sooty but I'm still running on year-old petroil so that's understandable. Gearbox oil looked very clean coming out so hopefully the seal is OK. Float bowl was clean as a whistle and compression was 125psi - PDG for 1973! Thanks again for the help.