Cooling Issue

[Frank Chyz]

1988 Mercury 100 HP OB. Its been in storage since end of last summer. Started right up today on muffs. Ran it for about 3 minutes but shut it down when I noticed no water coming out of the engine. Should it take a few minutes for water to begin circulating? I am afraid to run it and destroy the engine in the process.

 

[racerone]

The tell tale should show in a matter of seconds.

 

[Frank Chyz]

There is a small hole on the propeller housing just above the water intakes. Water is gushing out of it. Would that be normal?

 

[racerone]

Yes that is normal.

 

[Frank Chyz]

Do you suppose that this engine needs to be in deeper water (not just the muffs) for the pump to begin circulating?

 

[racerone]

Pressurized water has a LOT MORE AIR in it than lake water.-----So yes put it in the lake and test the cooling function / tell tale.-----If you do not know how old the impeller is you need a new one.

 

[Frank Chyz]

The impeller was changed at the beginning of last summer. Only had the boat in the water 3 or 4 times. I have not yet pulled it to the lake this year but will do so tomorrow. Thanks for the suggestion.

 

[racerone]

The tell tale is merely an indicator.----Most ( 93% ) of the cooling water comes out the prop !-----A plugged indicator hose is common and many folks will panic.-----But motor will still cool properly with a plugged tell tale hose..

 

[Frank Chyz]

That is reassuring to know.

 

[JohnnyBfromPeoria]

Simple idea, but that's all I'm good for - did you try cleaning out the tip of the tell-tale tube by poking something in it? Sometimes a bee/wasp or other bug will "hole up" in there and clog it up. My '78 Merc 900 had something in the very end and I just stabbed it with the straw from my carb cleaner can and it opened it right up.

John B.

 

[Frank Chyz]

Thanks for that tip. Once I trimmed the OB down into the lake, all was well. Tell-tale worked in seconds. Ran well all day. Thanks for your expertise. It's appreciated.