Yamaha cv85etld overheats!

So I bought a boat from my Dad after hearing nothing but good things about it, but so far it's been one problem after another. The most serious one is that the engine overheats. It has a good pee stream, but overheats at idle or running.

Today I ran it on muffs, checked the temps with an IR gun and when it got hot the alarm came on. The top cylinder is the hottest. Around 185 deg.

I removed the thermostat thinking it was probably defective and tried again with no difference.

Then I removed the entire thermostat housing. No water was coming out of the thermostat hole while the engine was running. It wasn't until the engine was about to sound the alarm that the water rose up to the thermostat level.

Does it seem that the water isn't circulating properly? Shouldn't I have water trying to come out the housing all the time while running?

I'm going to drop the lower unit and check the impeller next...

Re: Yamaha cv85etld overheats!

In my experience, it's normal to have one problem after the next. That's why BOAT stands for "break out another thousand". Check that your oil delivery system is working properly. If there is any doubt, run the motor only from an external tank with a 50:1 fuel/oil mix. But first check your owner's manual to make sure it's ok to do that. My Yamaha manual recommends starting the motor after storage with a 50:1 mix because the oil lines need time to get rid of the air gaps in them after storage. Having little or no oil can make a motor run hotter because without oil, there is metal on metal friction. If you find that the oil injection system is not working, then don't run the motor at all unless you're running it on a 50:1 mix or you will do serious damage to the pistons/rings/cylinders.

Re: Yamaha cv85etld overheats!

Problem found!!

Even though I had a good **** stream the impeller was missing some chunks and 2 of them were clogging the outlet of the impeller housing.

I guess I'll have a better **** stream from now on!!

Hope this helps someone else...

Re: Yamaha cv85etld overheats!

Toddboat said:

In my experience, it's normal to have one problem after the next. That's why BOAT stands for "break out another thousand". Check that your oil delivery system is working properly. If there is any doubt, run the motor only from an external tank with a 50:1 fuel/oil mix. But first check your owner's manual to make sure it's ok to do that. My Yamaha manual recommends starting the motor after storage with a 50:1 mix because the oil lines need time to get rid of the air gaps in them after storage. Having little or no oil can make a motor run hotter because without oil, there is metal on metal friction. If you find that the oil injection system is not working, then don't run the motor at all unless you're running it on a 50:1 mix or you will do serious damage to the pistons/rings/cylinders.

Click to expand...

Thanks for the advice. First thing I did was empty the tank and fill with a new 50:1 mix. This engine has no separate oil tank.