yamaha 30hp steaming

[vetazac]

Having problems with yam 30hp 2 stroke pumping great but then stream of water turns to steam and engine semi siezed. Freed up ok when cool but puzzled. Just fitted new impeller .

 

[cavscout]

Re: yamaha 30hp steaming

sounds like you need to pull the thermostat

 

[vetazac]

Re: yamaha 30hp steaming

Checked the thermostat and its already missing. I'm going to check the plugs tomorrow and see if the head gasket is leaking. Is it worth changing the head gasket anyway or am I heading in the wrong direction?

 

[deejaycee_2000]

Re: yamaha 30hp steaming

change the head gasket anyway .... seem like something got stuck somewhere , you need to flush out what ever is blocking it up .....

 

[vetazac]

Re: yamaha 30hp steaming

ran the engine in a tub of water with four dishwasher tablets dissolved in the water which washed out quite a bit of debris as i had great success with this method on my cars cooling system. Engine ran for an hour with no problems but I will change the head gasket anyway as it doesn't seem too big a job. Thanks for replying.

 

[deejaycee_2000]

Re: yamaha 30hp steaming

first time I heard of that method, but if it works for you then good, I was more thinking along the lines of taking off the lowerunit and exhaust plate and flushing a strong stream of water down the thermostat hole typa thing ......

 

[vetazac]

Re: yamaha 30hp steaming

When I first had the problem I removed the gearbox to make sure I hadn't missed anything when doing the impellor. At the same time I removed the thermostat housing and blew down the various pipework with compressed air. Nothing seamed to be blocked and when running has a very good stream of water from the outlet. Just wondering if it could be blocked in the waterways round the head. Never seen inside an outboard engine before so I'm going into it a bit on the blind side. Should have the new head gasket on Friday so might try it again this weekend and if I still have trouble will do the gasket next week. Thanks for your help.(p.s 2 dishwasher tablets in your radiator are great for cleaning out the brown sludge in car cooling systems. Run it for 1/2 hour then drain and refill. Run again and drain again .refill with water and antifreeze and your good to go.)

 

[vetazac]

Re: yamaha 30hp steaming

Removed cylinder head and the gasket has gone but I've found a stainless steel screw which would appear to be screwed into the exhaust manifold cavity from within the water jacket which would appear to have been surrounded with plastic metal. Should this screw be there or has somebody tried to bodge a hole between the water jacket and the exhaust manifold?

 

[2Smokinya]

Re: yamaha 30hp steaming

first time I heard of that method, but if it works for you then good, I was more thinking along the lines of taking off the lowerunit and exhaust plate and flushing a strong stream of water down the thermostat hole typa thing ......

I agree, first time I have heard of someone doing that, doesn't seem like too bad of an idea though.