Overheat / dry run Yamaha 115- Need advice

CastleRock4me

Seaman Apprentice
Joined
May 28, 2008
Messages
34
Here's the story (I was not there).

Boat was started and left unattended while he went to get the trailer. Got back to boat to discover the engine was trimmed all the way up out of the water and overheat alarm beeping.

He said it was running for approx 5 minutes w/out water. However, said it was still running fine (I am assuming at idle speed).

Pulled the lower and impeller housing was melted, will all be replaced.

I am going to run a compression test, check oil and probably cut the oil filter and examine.

1) What other damage can be expected? Is there a chance no internal damage occured?

2) What else should I be checking?

Thanks
 

KJM

Lieutenant
Joined
Jul 31, 2016
Messages
1,266
You don't say the year, but I'm told that if its a four stroke then you do a "leak down test" instead of a compression test. If thats good and she starts good and don't overheat then I'd be thinking you are very lucky! Was it your motor or one you are thinking of buying?
 

CastleRock4me

Seaman Apprentice
Joined
May 28, 2008
Messages
34
You don't say the year, but I'm told that if its a four stroke then you do a "leak down test" instead of a compression test. If thats good and she starts good and don't overheat then I'd be thinking you are very lucky! Was it your motor or one you are thinking of buying?
Its a 2017 4 stroke with 100 hours. It's half mine.
Thanks for the feedback
 

Sea Rider

Supreme Mariner
Joined
Sep 20, 2008
Messages
12,345
With an overheat depending how serious it was will need to retorque the cylinder head and exhaust covers gaskets back to specs. Check if possible with a torque wrench.

Happy Boating
 

CastleRock4me

Seaman Apprentice
Joined
May 28, 2008
Messages
34
With an overheat depending how serious it was will need to retorque the cylinder head and exhaust covers gaskets back to specs. Check if possible with a torque wrench.

Happy Boating
Thanks, I am trying to determine how serious it was? Assuming 5-7 min on idle runtime w/out water on an 80 degree day. What is the likely outcome? Do you know where I can get torque specs?
 

robert graham

Admiral
Joined
Apr 16, 2009
Messages
6,908
5 to 7 minutes dry at idle....my guess is that the only damage would be to the water pump, impeller, housing, etc....the cylinder head, etc. probably O.K.....replace pump,etc. and run it to see if there’s any issues...
 

KJM

Lieutenant
Joined
Jul 31, 2016
Messages
1,266
5 to 7 minutes dry at idle....my guess is that the only damage would be to the water pump, impeller, housing, etc....the cylinder head, etc. probably O.K.....replace pump,etc. and run it to see if there’s any issues...
That would be my thoughts too. If she starts and runs good then don't fix whats not broke.
 

Sea Rider

Supreme Mariner
Joined
Sep 20, 2008
Messages
12,345
Cylinder head, exhaust covers "Probably OK" doesn't say much, checking with a torque wrench will tell. The motor will run good, the issue is that on the long run could have slight water intrusion on those bolts gaskets and with time and use will end being seized, worse if boating in salted water. A friend of mine had near same overheat and a slight re torque was needed...

Happy Boating
 
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