Nissan/Tohatsu 50 engine trouble

[Kootkids]

Is anyone else familiar with 2000 vintage 50 hp 2 stroke engine problems? I am fouling my two lower cylinders with water, it does not seem to be a head gasket problem.
Wondering if anyone else knows of Nissan50 problems like this. Cracked cooling gallery??
I saw similar motors apart in shops in Vancouver this summer, I have not solved my problem yet.
Motor runs great at idle but when you power up it is ingesting water.
Exhaust manifold gaskets look good also.

[133bhp]

cooling gallery ?- corrosion probably. the fact that two cylinders are effected suggest its a common to both issue. as opposed to say a cracked/corroded cylinder head entering into one. I'd pull the exhaust cover, see what the galleries look like there?

Probably enough vacuum to pull water in off idle? whats the symptoms, steam, white smoke? runs rough?

[Kootkids]

Upon removing the exhaust cover, there is a line along the cooling gallery between Cylinder 2 and 3, it really looks alike a casting imperfection or a crack?

There is no such line on the 1/2 gallery.

The engine runs like a champ until it fouls the plugs after powering up..

[133bhp]

water in the crankcase too? but that's looking the favorite then - see if you use liquid gasket silcone. enough just to see if symptoms improve. or weld properly. ( tiny amount will be okay but ideally you don't want it to get into the head as well)

[Don T]

Hello,
There are anodes inside the water passages under the side plate. What kind of shape are they in? If completely gone or nearly so, I would suspect corrosion. The curious aspect for me is the "ingests at higher power settings" part. Under load a head gasket leak would result in exhaust gasses blowing in the cooling jacket not the other way around. Unless a pulse of exhaust gasses gets past the head gasket raising the cooling sys pressure to the point where water shoots back in. There is a possibility that water could get in through the exhaust side where it shoots in while the exhaust passages have a vacuum and the port is still open. I have the manual at home I'll take a look at it and see if it gives me any ideas.

Don T

[Kootkids]

Thanks,
I will check the anodes !
I have read about similar problems due to exhaust gaskets going bad, possibly the same symptoms as a cooling leak in the exhaust side.
http://forums.iboats.com/forum/engine-r ... atsu-m40d2

[133bhp]

engine anode is under the temp stat cover, another on the leg/trim tab, another on the tilt bracket. as I mentioned, vac off idle is probably enough to pull water in.

could well be the gasket, you took it off, whats it like?

[Kootkids]

The exhaust gasket looks pretty good, but there is a black area in the lower portion that is suspicious.
I slapped it back on with some RTV for some testing and the symptoms are much worse, fouling at idle cl#2 so I might be on to something. Hopefully an easy fix..
Cylinder compression #1 120lbs #2 115lbs #3 120lbs

[Kootkids]

New exhaust gasket! Fixed the problem!! I would highly recommend carrying a spare. Simple $4 fix or many many hours of troubleshooting.