i/o overheating

[aban_esox]

I would appreciate any advice any of you have concerning this problem. My friend and I took his 1976 140 Mercrusier out to Lake MI<br />yesterday. While proceeding out of the harbor at no wake (900-1000 rpm) temp rose to >220 degrees. When throtlled up temp drops to 140 or less. Impellar changed last year.<br />First, can these impellars be installed backwards?<br />Are we dealing with t-stat problem or water pump and is there a way to isolate problem?<br />Looking forward to hearig from everyone.

 

[corm]

Re: i/o overheating

Hi Esox,<br />Thats some cold water in Lake MI. You can't put the impeller in backwards. I would put the boat in the water start it up for a min to fill the block up then shut it off. Take the hose that comes from the transom plate and goes to the thermostat housing off at the housing. Start the motor up and see if water comes out of the hose right-a-way in a good stream. If it does then I would change the thermostat and go for a short ride to see if that is the problem. If the pump body and gaskets were put on correct and the water tube did not cut or fold the rubber gromet seals the pump should work fine. Although impellers can go bad in a year, it is not common. One other thing to look at is the water hose that joins the LU to the transom plate inside the gimble ring. Turn the drive to the right and trim it up till you can see a 5/8in hose in the left side of the housing, look for crimp marks or cracks.<br />If good you should be ok.<br />hope this helps<br />...have fun...corm

 

[aban_esox]

Re: i/o overheating

Thanks Corm;<br />followed your advice and by golly if it wasn't the impellar.<br />Everyone's taking their boats to the waupaca chain today and the weather today is going to be perfect so thanks for info. You know we only get about 12 perfect weather days a year here in WI.