2010 Volvo Penta 5.7Gi - Ran for 5 minutes and melted the Exhaust Overheat Sensors

plaborde

Recruit
Joined
Jul 26, 2015
Messages
1
Went to the lake today. The boat has been in storage for 3 years. It has 16.5 hours on the engine. We left the dock and it would not build up past 3000 rpm. I stopped when I heard a beep and turned the engine off. There was a small amount of smoke in the engine compartment. I guessed it was some oil or something, I restarted the engine and the boat went to full power. I ran it for 2 to 3 minutes and the beeping returned. I stopped the boat and lifted the engine access area with the engine running. I noticed that the boat had not been de-winterized as I saw water pouring into the engine area. The temp did not get above 180 degrees indicated. I installed the three hoses and installed the four block plugs. The insulation on the piping after the exhaust risers was bubbling. I noticed that the overheat sensors had melted out of the exhaust risers. I restarted the engine and it cooled to 175 degrees. I ran the engine for another 2 hours and it rose to 180 degrees when going slow and dropped to 175 at speeds over 20 mph. I know the water pump impeller is toast and has to be replaced. My question is about the Exhaust overheat sensors at the rear of the exhaust sensors. How do I replace them? they are melted and no longer in the riser. What else do I need to look for? The engine would run to 5000 rpm and the boat attained a top speed of 50 mph with 4 adults, which is normal at full trim.
 

skydiveD30571

Lieutenant Junior Grade
Joined
Feb 13, 2012
Messages
1,042
Hopefully next time you atleast give the engine at lookin' at before starting her up after 3 years. The impeller does need replaced, and if the current one is missing any vanes you'll have to track them down upstream (typically caught in the thermostat housing). The exhaust overheat sensors are built into a brass housing that screws into the back of the exhaust riser. It is difficult to see, but if you search for new sensors online, you'll see what I mean. They just unscrew out with a socket. Also check the 2 rubber bellows for cracks or holes...once they start bubbling and melting they begin to leak usually.
 
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