180 Sport Overheating

surfinjoe

New Member
Feb 23, 2007
946
Michigan
Boat Info
220 Sundeck 2007
Engines
350 MAG w/Bravo III
Last week my boat overheated at WOT. I shut her down and took a look and couldn't find anything wrong. She had been running fine all day, pulling tubes and running at WOT several times.

I let her cool down and everything went back to normal (including the temp.). Then I anchored for a while and enjoyed the sun. When I fired her up and went back to the dock, she would not get up to heat (~120 deg.).

Does this sound like a bad thermostat? I replaced it two years ago. I was in a sandy lake. It is possible that sand got into the thermostat and wreaked some havoc?
 
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Sounds like it could be the thermostat. When was the last time you changed the impeller in the outdrive? Being in sandy water your impeller could be starting to fail. I boat in the Mississippi and the water is pretty sandy so I change mine once a year to be safe.
 
Sounds like it could be the thermostat. When was the last time you changed the impeller in the outdrive? Being in sandy water your impeller could be starting to fail. I boat in the Mississippi and the water is pretty sandy so I change mine once a year to be safe.

I have never changed the impeller in the outdrive. When I think of Impeller I think water pump. What is the function of this impeller? The manual doesn't talk about changing this part so I was not aware that it is a maintainance item. The boat only has 85 hours on her (a shame I know). Also, would a bad impeller in the OD cause the engine to not reach operating temp?

I don't run in sandy water, but when I beach I assume that some sand does get into the OD.
 
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If you fired it back up and it would only get up to 120, the impellar has to be good, it's getting so much water it won't get warm. Has to be a thermostat. Do you run in salt water? That stuff is brutal.:smt009
 
If you fired it back up and it would only get up to 120, the impellar has to be good, it's getting so much water it won't get warm. Has to be a thermostat. Do you run in salt water? That stuff is brutal.:smt009

I ran her in the ocean a couple of years ago and did not change the thermostat since then. I will tear it apart and see WTF is going on. Is the impellar a maintainance item?
 
I ran her in the ocean a couple of years ago and did not change the thermostat since then. I will tear it apart and see WTF is going on. Is the impellar a maintainance item?

Yes...
 
If you didn't flush your engine properly or soon enough after you ran it in salt, it could have rusted the thermostat spring, thus causing failure. Thermostats are extremely sensitive to salt. If you didn't flush it at all for some time before you ran it in fresh water, you may want to check the freeze plugs as well. They are made of the same grade corrosive metals.
 
I removed the thermostat last night and it looked a little bad, but not terrible. It did seem to stick a little so I will just replace it and see what happens. To me, it looks the same as a Chevy 350 thermostat does. Is it in fact the same? Can I get it at Autozone or do I need to buy the special $20 model at West Marine? It's not the money, but the drive that I want to avoid. I have an autozone two blocks from my house and West Marine is like 1/2 hour. Maybe I am just being lazy!
 
The impeller is a small _pre_water pump in the outdrive. On a outboard it is the ONLY water pump used to cool the powerhead (motor), on a I/O it is there to feed water for cooling to the water pump on the inboard motor which is like a water pump on a car motor. The impeller can be damaged in many ways but usually a two year change is standard, but if the boat has been started without ears on the outdrive for even 15 seconds once, you really need to change the impeller, and possibly the pump housing and seals.

What sounds like is happening on yours though is the thermostat. It probably stuck closed then open.

Be safe though and change the thermostat, and the impeller/waterpump on the outdirve.
 
surfinjoe,

Use the thermostat from west marine. it is desinged for marine application. there is a WM store at 14 & dequindre.

Do not use gasket seal (the permatex stuff). you need to only use the felt gasket that comes with the thermo. Make sure you have two clean surfaces (on engine block and housing).

As previously stated, the impellar is in the lower section of the outdrive, and is a maintenance item.

Gregg
 
Was the old thermostat open when you removed it? According to your last symptom, it should have been open. If not, then you may need to look further. Not sure what else to look for though in a "would not get up to heat" situation!

If its closed, to test if it's opening properly and at what temp, you can stick the thermostat in a pot of water on the stove to test it. Stick a thermometer in there and see when it begins to open.
 
If it's not the thermostat, could it be the temp sending unit gone a bit haywire?
 
Mine was not achieving operating temperature. Took it back to the dealer & it was the thermostat stuck open, have only done 24 hours. It started happening not long after I motored onto a shallow sand bank :smt101
 
If it's not the thermostat, could it be the temp sending unit gone a bit haywire?

No, It did overheat. The engine was really hot and she would not stop running when I turned the key off (dieseling). Thanks for the idea though.
 
I replaced my thermostat last week and ran her again. Damn thing overheated (again). The only thing that I can figure is that the impeller is bad. I opened up the radiator hose above the engine water pump and filled her up with lake water and she ran like a champ (at normal operating temp). This means that the engine water pump had enough water to start pumping and cool the engine (not the way SeaRay intended I know). Any good links to a helpful website for pointers/directions?
 
Go to Mercstuff.com and read direction on how to change impeller in the outdrive. The impeller it not too hard to change. Don't take chances with your $4000 engine. http://mercstuff.com/waterpumpinst.htm
 
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