9.9 Merc Cooling Water Question

[fisherman7]

Hi all, quick question - does all the cooling water flow through the tube that puts a jet of water out the side of the motor or is that just an indicator?

 

 

[Sinker]

Just an indicator. The water that actually cools the engine will come out through the prop or a lower port somewhere depending on the year of engine.

[Fisherman]

Just an indicator. The water that actually cools the engine will come out through the prop or a lower port somewhere depending on the year of engine.

Whoa, then why is the water jet warm after the motor has been running a while.

[Sinker]

On a merc? Mine never gets warm.

 

S.

[OhioFisherman]

I believe the water that comes out of the tattle tale is actually part of the water used to cool the engine.

[misfish]

It,s part of the cooling system. If you got no pee coming out, see how fast you over heat.

[Joeytier]

On a merc? Mine never gets warm.

 

S.

The stream from my 08 Merc 2stroke gets quite warm.

[Sinker]

It,s part of the cooling system. If you got no pee coming out, see how fast you over heat.

Thats not true. I have been out in below zero temps many, many times and my tell tale was frozen, but the engine is still pumping water. Its an indicator that you are pumping water, and that is all. I am not positive about any engines but my own, but both of mine pump the hot water out through the prop. The water coming out the tell tale is just overflow that is an indicator that you are pumping water. Im not trying to argue, just saying what i know about my engines. I have a 91 mariner 40hp.

 

S.

[misfish]

The pee hole tells ya if you have circulation. Like you said, yours was froze up, maybe the water is cold enough then to keep the motor cool enough. Never argue with ya bye, you know that.LOL

[mike rousseau]

Just an indicator as far as I know... only a portion of the cooling water comes out there...

 

If it's not peeing there's a chance it may be plugged or frozen elsewhere...

 

I'm no mechanic tho

[chris.brock]

 

The indicator (pee hole) is some, but not all of the circulated cooling water.

 

I'm guessing Shane's Mariner has the pee hole outlet before the water is circulated through the cylinders/ head.

[Sinker]

The indicator (pee hole) is some, but not all of the circulated cooling water.

 

I'm guessing Shane's Mariner has the pee hole outlet before the water is circulated through the cylinders/ head.

Yes exactly.

[Old Ironmaker]

I have been taught if the overflow at the top is not pissing overflow the upper section of the cooling chamber is not being cooled. The impellor is not working properly. The water that comes out of the exhaust cools the lower gear. I will not run an engine without water overflowing well.

[Roe Bag]

The indicator (pee hole) is some, but not all of the circulated cooling water.

Exactly.

The whole cooling system is pressurized by the impeller. The indicator/pee hole allows a small portion of water to exit. Letting you know that circulation is present. The remaining circulating water exits at the prop.

A good impeller will show a strong steam. As the impeller wears the stream will diminish.

When the impeller completely fails, there will be no stream and you engine will soon overheat.

Another cause for poor or no circulation can be a plugged strainer on the underside of the cavitation plate. (water intake)The strainer prevents foreign matter from entering the system.

The rubber compound used in an impeller has a tendency to dry out and break down. Yamaha recommends replacement after 300 hours or every three years. The interval seems excessive but a small price to pay for peace of mind.

Hope this helps.

Edited October 11, 2016 by Roe Bag

[JoePa]

I have a 1991 OMC 40 HP motor and have never changed the impeller on this motor - I know that so many people say that it needs to be changed quite often but so far I haven't had any problems - but just in case I bought a replacement kit this pass summer and intent to change it in the near future - looking at what has to be done it looks like it is easy enough to do - that is after I figure on how to disconnect the shift rod up the motor head -

[fisherman7]

Thanks all. Took the pee tube apart. It was completely clogged with what looked like too much lock-tite. Cleaned it up and it's pees like a racehorse now!

[Old Ironmaker]

Good news Fisherman7. A stiff piece of weed whacker line through the overflow helps if she's clogged up. Also a quick shot of a pressure washer through one of the lower inlets has helped clear crud in the cooling system before changing a good impellor. A pal left his engine down and creek water guck plugged the thing up, the power washer did the trick. He plugged one lower inlet and blew water up the other inlet, just a quick shot.

 

I have to add that on my big Mariner the tell tale stream will only show when the thermostat opens. Running on cold water in cold weather with the muffs on I freaked when I didn't see any water overflowing. I had to get my engine Guru out here and he explained it to me and laughed. But not before he gave me some line about a blown water pump that would cost 500 bananas, funny guy.

Edited October 12, 2016 by Old Ironmaker