marine yanmar engine overheated is it ruined?
We have a 1985 Yanmar 3GM30 with 2200 hours on it.
In April 2010, I just changed the oil, transmission oil, oil filter, secondary fuel filter, zinc, and water impellor gasket (not the water impellor).
The engine is raw water cooled.
After all of this maintenance we took the boat out for a trip and used the engine for about 2 hours. There was no problem.
Then this weekend all hell broke out.
When we started the engine up, we saw water coming out of the exhaust so everything seemed fine. We motored out of our marina and up the river. After about 15 minutes an engine alarm went off at the starter panel, I flipped the RPM switch and the alarm turned off but the RPM needle stopped reading also. I figured it just shorted or something. About 5 minutes later the engine turned off.
We wern’t sure why it stalled but, it has stalled before so we just started it back up and after a few trys it came on. This only lasted about 1 minute then the engine turned off again. So we said owell and put the sails up and sailed up the river.
A couple minutes later we noticed a light smoke coming from the cabin. Fire extinguisher in hand I opened up the engine compartment and there was alot of smog/smoke coming off the engine. We opened up the cockpit engine access too to let smoke out but there was no fire.
At this point we realized that the engine has overheated.
We sail for another 45 minutes untill we lose wind and without the wind power we accidently run aground. The smoke had all cleared and the engine wasnt as hot so we attempted to use the engine to get us off the ground. The engine came right on and we used it for about 5 minutes before giving up and turning off the engine.
We called Boat US Towing and they pull us off the ground. At this point we should have let them tow us home boat we thought the enigne wasnt so bad since it came on and worked fine after cooling off so we just had him let us go and we sailed to a near by anchorage. When we got the anchorage we turned the engine on for about 2 minutes to get in a good location, at this point we noticed that no water was coming out of the back exhaust. I went below and saw a slight leak at the hose between the water filter and water pump. I tightened that hose as well as all the other hoses related to the cooling system. We tried the engine again and still no water came out the back so we truned it off and left it off for the night.
The next morning we opted not to use the engine and sailed off the anchor and out of the anchorage. But as we were leaving the wind was not strong enough and the current threatened to put us aground again. So as a last ditch effort we turned on the engine to attempt to get us away from the shoal. But instead the engine stalled in forward gear, and would not return to neutral or reverse. We abandon the engine option and manage to dodge the shoal via sail.
On the sail back home, I went down to the backside of the engine compartment to check out why the gear would not leave forward. It was just stuck and only moved slightly back and forth but not enough to enter neutral or reverse.
Also while I was on the back side I noticed that the plastic container between the exhaust manifold/elbow and the exhaust pipe where the exhaust and water meet has partially melted and there was a large hole in the side of it. There was also oil sprayed around this area of the engine compartment.
We had Boat US Towing put us back in our slip and now we have some repairs on our hands.
My plan is to focus on the cooling system and transmission. I will change the water impellor, check/replace all tubing, and ofcourse replace that plastic mixing container. On the transmission side I will consult a Diesel mechanic.
One mechanic friend of mine said that I probably ruined the whole internal engine and will need to have a complete rehaul or buy a new engine.
So my question is, do you think this engine is ruined and what advice can you give me on repairs?
We have a 2 Gm in the sailing fleet it has been overheated more times than i can count melted the exhausted completely off. Before U do anything check the oil for water. Change the trans fluid and see Y it won’t shift replace the muffler and exhaust hose water impeller is gone from running without water. Those trans boxes will take a lot abuse.
After you pull the dipstick and make sure there is no water, check the expansion tank to make sure there is water/anti-freeze mix. If there is water you will have to pull the head and change the head gasket. There may be more damage that you will have to check for. Scoring of the cylinder walls etc.
That “mixing can” sounds like your water lift muffler that burned up when it ran dry. The transmission will not shift most likely because the spool or selector valve seized up in the bore as it expanded since the trans fluid was getting too hot. You should be able to take it out and clean it up with very fine sand paper. Put new o-rings on it also. You need to check downstream from the impeller and fine any pieces of it that may have broken off when it ran dry. Was the sea cock open when you started the engine?
My Grandfather was a diesel mechanic, my Father drove 7 million km as a professional truckie. I run my own and other peoples boats for pleasure and commercially. One golden rule – if an alarm or warning light goes on, stop and locate the problem. That is just practical experience relayed from at least a combined 100 years of professional experience.
No matter what originally happened, continual running will have only added damage, and increased repair costs significantly.
Yanmar’s are a good engine, with a well deserved reputation. Overheating any diesel is not a good idea as they need good tolerances to function. Until you examine the engine internally you will not have any real idea on potential damage, you have little choice other than to pull the engine down enough to get access and find out.
Good luck.