Nissan 9.9 hp 4 strokes

[genoq]

Hi,<br /><br />I just bought a 2002 Nissan 9.9, 4strokes. Started it, it seems to run well but the idle is a little rough. The problem I have is that I see smoke (or steam) coming out a hole in the upper part of the shaft. This is not the pee hole for the water pump. I am told it is the pee hole for the thermostat!!. Is this normal??? I thought 4 strokes were not supposed to smoke.<br /><br />I should also say that during transport, the engine was on its wrong side and some oil spilled. I checked the plugs and they were dry..<br /><br />Thanks in advance

 

[beau123]

Re: Nissan 9.9 hp 4 strokes

Not to sure. Try posting on Nissan Troubles/Repair

 

[DJ]

Re: Nissan 9.9 hp 4 strokes

1. Is the engine full of oil? Check, standing the engine straight up and down.<br /><br />2. The steam is different from smoke. Do you have a full stream from the telltale?. <br /><br />3. Some steam MAY be normal from the exhaust relief (just below the powerhead).

 

[genoq]

Re: Nissan 9.9 hp 4 strokes

1. yes the oil is ok<br />2. water is flowing from the telltale<br />3. The hole from where the steam or smoke is comming out is just below the powerhead...so maybe I should not worry<br /><br />Thanks

 

[genoq]

Re: Nissan 9.9 hp 4 strokes

Maybe I found the explanation to the question I asked. While surfing on the net I found this description of the exhaust system<br /><br /> "All cylinders dump exhaust into a common manifold where water is introduced to cool and muffle it. The exhaust-water mixture then passes down a passage in the drive unit and eventually exits through the propeller hub. When a boat is at idle or slow speeds, however, the static water around the prop produces too much resistance to the exhaust, resulting in excessive backpressure. (When the boat is moving, a low-pressure area behind the propeller prevents this.) To alleviate this problem, one or more passages are cast or machined into the intermediate housing just above the waterline. If pressure builds at the prop, the exhaust can escape through these ports. If these ports are restricted—say, by overloading the boat to the point where they are submerged—exhaust won’t escape, cylinder temperatures and pressure will rise, and deposits will form."<br /><br />I was testing my outboard in a buccket, which may create a back presure and force some of the exhaust through the relief port.<br /><br />Cheers