Where's my thermostat? 15 hp merc

[stuffer]

I think I have a cooling problem.I ran my '98 15HP merc for the first time since I bought it from a private owner.I ran it about seven or eight minutes and no water come out.Yet it didn't feel overly hot when I touched the heads.Now I'm afraid to run it.I'd like to change the thermostat and waterpump impellar.Is this a big job? I'm mechanically pretty handy but never worked on Outboard motors.Where is the thermostat?what doesit look like?<br /><br />Bill

 

[dcm3372]

Re: Where's my thermostat? 15 hp merc

Hi,<br /><br />In your situation I cannot over-stress how important a workshop manual will be.<br /><br />When I first started working on outboards, I didn't realise how important it is - but I've learned it's critical and doesn't cost very much.<br /><br />That said, thermostat and water pump impeller replacements are usually not a big job but the manual will let you study the job in hand before undertaking it.<br /><br />Good luck,<br /><br />Dan

 

[schaiss]

Re: Where's my thermostat? 15 hp merc

Your engine is not fitted with a thermostat. Check the hose to the tell tale hole to be sure it is not obstructed. You mentioned that you did not beleive the engine was running hot, if you can place a hand on the head after running WOT for about 5 minutes (head should be quite warm allowing you to keep your hand on it for e few seconds) then cooling water, flow or pressure, is not something to be concerned about. BUT... the water pump impeller should always be replaced at least every 3 years anyway !!!

 

[CaptainPuget]

Re: Where's my thermostat? 15 hp merc

Your engine should have a 120 degree thermostat. It is located under the thermostat cover (the thing that the hose to the tell-tale comes out of). Yes a manual is a very good thing.

 

[Prospector]

Re: Where's my thermostat? 15 hp merc

I also have a Merc. 15HP (2 cycle) and I know I don't have a thermostat and would be very surprised if you do. There is a place for one but it is rare to have one installed on this engine unless you are operating in a very cold climate/water. I suspect your tell tail could be plugged. Its common to find that a dirt dobber wasp laid an egg in the tube. Try running a piece of weed wacker string into the tell tale hose or remove the the hose from the block and blow it out.

 

[moonstruck37]

Re: Where's my thermostat? 15 hp merc

Just found the corroded thermostat on my Merc. 15HP (four stroke). It was under plastic facing above some solenoid. There are some really good videos on youtube how to replace it yourself. This is one that I found to be helpful even though he wasn't working on the same motor. http://www.youtube.com/watch?v=CLIKKXnM3pk