Yanmar Diesel in Hunter 31, Boat went in the water today. It has not been in the water for 4 years. I found water in the fuel and drained the tank, all the filters were changed an new fuel put back in the tank, Started the motor on a hose and it ran fine. Launched the boat started the motor and everything seem fine, The motor started to gradually knock and slow down, it got to the point that it would only idle. I thought maybe the filter was clogged and could make it back to my mooring. it start to blow black smoke and a sheen of soot on the water. I shut it down, it will start but only at an idle and I get that soot out of the exhaust. any ideas?
engine die above an idle
- Thread starter Hunter 31
- Start date
So, how long did you run the engine at idle? How soon did the knock start?
Have you changed the engine oil and check the oil level?
Black soot indicates un-burned fuel which could be caused by excessive load on the prop shaft due to misalignment.
Have you changed the engine oil and check the oil level?
Black soot indicates un-burned fuel which could be caused by excessive load on the prop shaft due to misalignment.
I ran the engine at idle for 20 min or so. I just change the oil and filter and I put 2 quarts back in. the engine blows soot in neutral tied to the mooring ball.
It's not burning the fuel for some reason. Maybe start by checking the air filter to make sure it's getting air to mix with the fuel. Next for a Yanmar would be if the exhaust elbow is clear. Overheating could also cause that - Does it have a temperature gauge or working overheat alarm? And was water flow out the exhaust normal?
I checked the air filter, that was changed, I do see that as a problem. I am going back up to the boat tomorrow. I can start it and see if it acts normal when I first start it, if that's the case I will know its overheating. Any suggestions on how to check the exhaust elbow?
Thanks
Thanks
That make since. I hope it is not too rusted and I can get it off the motor. Im on my way to the lake with new hope, its impossible to get a mechanic right now.
Thanks Hunter 31
Fair wind and Following seas
Thanks Hunter 31
Fair wind and Following seas
The mixing elbow is an easy thing to change out if you can get it off. It is easier if you take off the manifold that the elbow and riser tie into then try to remove the elbow. The manifold has just four bolts. PM me if you need someone to talk you through it.
Since he is on fresh water, his elbow may not be a problem.. (could be but may not be)
Since the fuel is not burning, I'd look at valve lash (clearance) and fouled injectors.. Fuel in the lines between the filter and HP pump and between the HP pump and the injectors may have grown algae foulants while sitting..
Be careful if cranking and not firing because cooling water will collect in exhaust and flood engine after only a couple or three minutes..
Since the fuel is not burning, I'd look at valve lash (clearance) and fouled injectors.. Fuel in the lines between the filter and HP pump and between the HP pump and the injectors may have grown algae foulants while sitting..
Be careful if cranking and not firing because cooling water will collect in exhaust and flood engine after only a couple or three minutes..
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As HMT2 says, remove the four bolts (at the hot exhaust inlet) and then get it in a bear hug and wrestle the hose off. It will almost be welded on there after not being taken off for several years. A hair dryer may help. Apply parting compound to the hose fitting before re-assembling and it may be about 0.1% easier removal next time. Watch the RH and LH threads when playing with this thing.
I went to the boat yesterday. The bolts are pretty thought. Sorry to say I through in the towel and talked to the marina. They are raising the mast tomorrow and he was nice enough to look at it. Break Out Another Thousand. Thanks For the info I at least have an idea if he is honest with me. Ill post the results when they are done.
Ok round and round we go. The exhaust elbow was clogged. Thanks for the help. Mast is going up and off we go.