Mariner 2.5hp exhaust spray

[alecB]

Hi, this has probably been asked before but I can't find it elsewhere on the forum, apologies for missing the obvious if it is there:

I have a Mariner 2.5hp 2 stroke approx mid 90s, starts and runs perfectly, has fresh impeller installed, and is run in fresh water only, though previous owner may have had salt water use. The telltale produces water stream ok (though prone to very occasional blocking, which is easy enough to clean through the rubber tube to the head with a thin wire).

I noticed that the holes in the exhaust leg below the bracket that lets out the exhaust also has a fine spray of water coming out while running. The engine is run with water up to just below the top small horizontal fin, in a large bin without the prop on at the moment, to keep it ticking over, as this summer's sailing has been lost due to family comittments.

Is this normal? Or is it a sign that problems are on the way, and if so what should I be doing about it? thanks

 

[VicS]

It is normal for some water to be blown out of the back pressure relief port(s)

The bulk of the cooling water will leave under water via the main exhaust outlet.

You may have it a little deeply immersed causing more gas and therefore more water to be blown out of the relief ports than would other wise be the case.

 

[alecB]

Thanks VicS, what would you recommend as the best depth for the leg? I'm always wary of the impeller being out of the water if set too high, so probably have over compensated.

 

[VicS]

Thanks VicS, what would you recommend as the best depth for the leg? I'm always wary of the impeller being out of the water if set too high, so probably have over compensated.

Normally OK if the anti- ventilation plate is about an inch under water but I believe the impeller on that one is on the prop shaft behind the prop so if the prop is immersed so is the pump.

Still need to immerse the exhaust outlet though or it will be rather noisy.

 

[alecB]

Normally OK if the anti- ventilation plate is about an inch under water but I believe the impeller on that one is on the prop shaft behind the prop so if the prop is immersed so is the pump.

Still need to immerse the exhaust outlet though or it will be rather noisy.

Thanks again VicS, as you say the impeller is behind the prop so I'll do the inch above thing from now on, cheers.