Classic 50 - 45 hp overheating

[reconmarine]

Does anybody know what may be causing my OB motor to overheat? I have replaced the impellor and the telltale is spraying a strong stream of water. When you accelerate, though the stream turns into steam and steam comes out of the upper exhaust outlets. Idling and low speeds are fine, although the water seems a little hot to me. Any ideas? Does this engine have a thermostat?

 

[emckelvy]

Re: Classic 50 - 45 hp overheating

Don't think even a Classic 40 has a 'stat but could be wrong.<br /><br />Likely you have impeded water circulation in your powerhead. <br /><br />Try pulling off the cyl block water jacket cover (the bolted cover over the spark plug holes) and check for silt/debris buildup. I've seen them half or more full of trash and water doesn't circulate very well at all!!!<br /><br />With the back cover off, and the lower unit removed, you can flush thru the water supply tube up into the powerhead, to check water flow and also to help flush any other trash out of the powerhead.<br /><br />P.S. make sure your motor is mounted at the correct height upon the transom, also that the hull bottom has no problems that would cause water flow under the keel to be disrupted when the boat is on plane.<br /><br />HTH and Good Luck......ed

 

[btatum]

Re: Classic 50 - 45 hp overheating

i've got the same engine on my 17' bass boat. you may want to drop the lower unit and ck the pump impeller (just to be safe) have seen the same type problem and the impeller had come appart. how long has it been doing this? and why did you replace the impeller?<br />Ed Mc could be right also sand will settle in the lower half of the powerhead and cause an overheating problem.

 

[reconmarine]

Re: Classic 50 - 45 hp overheating

O.K., I have dropped the lower unit - the impellor is fine. I have pulled the exhaust cover from the side of the engine - all clear. I also pulled the back cover off - all clear. I blew through all of the passages with compressed air - all seems clear (including from the water uptake on the lower unit). I removed the water pump body for inspection - seems O.K.. I am pulling my hair out now. What might I be overlooking?

 

[reconmarine]

Re: Classic 50 - 45 hp overheating

Ed - I regrouped and had another look - seems the main passage from under the cylinder area to the exhaust cover was packed tight with bits of the old impellor. The water through the water supply tube did the trick after I stuck a piece of wire through the jam. Sure appreciate it Ed. Brian.

 

[emckelvy]

Re: Classic 50 - 45 hp overheating

Wow, that'll do it! Any time you replace an impeller and you notice that blades are missing, you've got to wonder where they've gone, if you can't find all the pieces. Bad thing, like yours, is when they head to Parts Unknown in the powerhead and start acting like flapper valves!!<br /><br />Of course, no way to know the history of a motor if you don't happen to be the original owner, thus the need for exploratory surgery! <br /><br />Glad you found the problem...........ed