Two stroke 85 HP Yamaha on a pontoon boat. I started it and let warm up, checked the water pump and had a good strong stream. After a bit I backed out of my dock, moved away at almost engine idle, after about 200 ft the engine high temperature alarm sounded and notice the water pump had quit. I turned the boat around and headed to the dock, killed engine and coasted to dock stall. I was concerned may have let it run too long without cooling but checked it this morning and the engine turns over with the starter just like before. Also tried a rope on it and it turned over ok.
Question, by the engine not being seized, is this a good sign that no damage occurred to the engine?
Are you in fresh or salt water? Were you at idle-speed in reverse or forward? It could be something as simple as a flooded engine or not-so-simple as you need a new waterpump. They can quit that quickly…what year is the Yamaha?
Fresh water.
There is no problem with engine speed. I was holding it slow on purpose.
Year… 1994, I bought it new.
Have never replaced the water pump or impeller. In fact, only maintenance I’ve ever done to the engine is change the gear oil a few times. Always add Sta-Bil for winter storage.
You probably didn’t damage the engine significantly. Water pump life is two years with little to light use and annually or more often with heavy use.
This is a classic "it should be okay’’.
Change the water pump. Hope it didn’t go to shreds and get into cooling passages. It happens on boats. You replace it to find out it jacked up the cooling passages for the engine/exhaust.
Also, if easy, throw in a new OEM t-stat. Get on it, and report back. I’d like to hear.
**Philster, **
Thanks, I hadn’t though of replacing the t-stat.
I’ll have to take a chance on if it fouled the cooling passages. It will be after boating season before I have the work done for they are so busy. I don’t have a trailer. I’ll tow it to the marine with my fishing boat. I’ll post back after the work is done.
MikeF,
Nothing over the intake but thanks for the suggestion.
Guess I been lucky, in 40 years of boating I’ve never had that to happen.
I read the title and thought I should be able to help. As I was reading the first line I OK, the 85 Hp what? read it again 85 HP, oh different type of marine engine, little one.
I agree with what has been said, maybe little damage.
I would think it’s probably plastic.
As far as doing the job, the boat is in the water… well it’s actually raised out of water for I have a boat lift. Also have never owned a trailer.
As stated, check the impeller. Often, a worn/defective impeller provides initial ample cooling water at idle speed but as friction causes it to heat, its efficiency decreases.