Yanmar 18 HP Troubleshooting

[J Stage]

A couple of blackish puffs of smoke from engine compartment.Went from 5 knots to neutral to slow engine down entering harbor, when accelerated to get enough speed to get into slip, smoke came out into cabin from the engine. Immediately put it into neutral and smoke cleared.Can see no obvious place the smoke came from.Checked the strainer, it's clear.Water is coming out the back so pump is working.Transmission fluid is a bit on the low side, but measured when engine was hot. (Do you pump out old fluid and replace or just add?)Overheat alarm did not sound.Antifreeze level normal.Ran the engine in neutral twice for five minutes after docking and everything seemed normal. But something isn't correct. Nearest engine person is 10 miles away. Any suggestions? Torreson's discussion site is down until July 15th. Thanks, Joan

 

[Jerry]

In Gear Pressure

Maby when you are in gear and have a load on the engine the exhaust tube may be split and opens, the mixing elbow may be clogged or its threaded connections may be loose. Is it diesel smoke or water steam?

 

[Andy]

Been Fishing?

Sounds like something in your drive train is putting a bad strain on the engine. Is it possible that at you entered the harbor you snagged a fishing line, old mooring line, or lobster pot line? It may be wrapped up on you shaft and strut causing it to choke the engine.You would be amazed how a old twisted dock line can choke a diesel.

 

[John]

mixing elbow

Had the same thing happen to me last week. The coupler that attaches the exhust to the mixing elbow had broken and the cabin filled with exhust smoke. See if the mixing elbow is loose on the back left side of the motor.Should be two rubber hoses attached. One large for the exhust and one smaller where the raw water mixes with the exhust. I had to remove the aft cabin wall to access the back of the motor for repairs. Ordered parts from torresin. Parts:1. Gasket 128370-13201 $3.832. Rt. Angle Elbow 128370-13610 $105.523. Threaded joint 104214-13580 $25.764. U elbow 124070-13520 $120.31Hope this helps

 

[ken matejka]

me too!!

I experienced almost exactly what you describe. Wasn't there some water in the engine bilge as well?? Anyway, my elbow coupling nut was cracked and was leaking small amounts that were not noticeable when the engine was running, but the leak was definately there. Try this, start the yanny at night then go below and take the engine cover off with only a flash light on and shine a focused beam into the engine compartment. My bet is that you will see plenty of fumes that are there but really not that noticeable in the daylight. You can also reach around the motor and feel for leaks when she first starts up, before the exhaust elbow gets hot. Then it is an easy remedy, remove and replace the whole thing--all three exhaust parts. Many articles about this in the archives. I recommend removing the hoses first, then remove the exhaust elbow from the block, then take the pieces home to get them apart (as you will need a table vise, a large pipe wrench and a 5 foot cheater bar), if you are going to reuse any of the parts which I do not recommend. Might as well buy new if you are spending the time to do the job. Also, if the baffle inside the mixing elbow(which is also likely to be badly clogged when you remove it--try blowing through the water inlet to prove this to yourself) fails then water can be pumped into the cylinders--way more expensive to fix than these few exhaust parts. Oh yeah, one of the threads on the coupling nut is reverse threaded if you are going to try taking it apart.

 

[J Stage]

Thanks for the suggestions

Engine mechanic is coming to check it all out. Decided I didn't want to depend entirely on the wind to get the 10 miles to the marina. In our case we now hire out these jobs. He is aware that Yanmar's often have mixing elbow problems. Our engine is 9 years old. We do alot of sailing but little motoring. Very seasoned citizens. Fair winds. Joan