Cooling on a 1983 Evinrude 7.5 - basic question

[billinengland]

Please excuse the basic nature of this question. I have just acquired an old second hand Evinrude 7.5hp which (from the serial no) was apparently built in 1983. It seems to run fine, but I have some concerns regarding the cooling. <br /><br />When the engine starts and is cold, there is a healthy stream of water from the 'pee-line' under the engine cover. Once the engine gets warm however, after about 5 minutes or so, the stream of water reduces significantly. Is this normal? If so, what is going on?<br /><br />I have ordered a repair manual and hope to be able to resolve this (if it needs resolving) once it arrives. In the meantime, the weather here is getting better every day (albeit slowly) and I want to get on the water as soon as possible. I would therefore be grateful for a steer regarding whether I can use my engine in its current state or not.<br /><br />Many thanks in anticipation..................

 

[Paul Moir]

Re: Cooling on a 1983 Evinrude 7.5 - basic question

Bill - first off, welcome to Iboats!<br /><br />There's a thermostat in your engine that opens like a valve and lets water out, and new, cool water in when the engine heats up. When the thermostat opens the pressure on the cooling system drops. Before that happens, the tell-tale is pretty well the only relief for the pump.<br /><br />It's like having a shower running upstairs (tell-tale) when someone flushes the toilet downstairs (thermostat).<br /><br />Even if there is no problem with your engine, these outboards need routine maintance. The impeller in the water pump should be replaced at least every other year, and the thermostat should be inspected at least once a year. At the very least, that will keep the bolts from getting corroded in place. A service manual will explain the process in detail.<br /><br />A weakening (or weak) tell-tale is usually a symptom of a wearing out water pump impeller.<br /><br />I hope this explains it!

 

[billinengland]

Re: Cooling on a 1983 Evinrude 7.5 - basic question

Paul,<br /><br />Many thanks for your help - I will definitely replace the impeller and probably the thermostat once I get the manual through the post.<br /><br />I am still confused by the purpose of the 'pee-line', given that most of the water cooling comes out of the outboard leg below the water line. Is the 'pee-line' just a visual indication that everything's OK or is it cooling something that the rest of the main water cooling isn't? What does it mean if the amount of water coming out of the pee line gradually reduces to either a dribble or nothing?<br /><br />Sorry to be a dullard, but I'm used to sealed cooling (car) engines - much easier to figure out and less to worry about!<br /><br />Again, thanks in anticipation......

 

[DJ]

Re: Cooling on a 1983 Evinrude 7.5 - basic question

billinengland,<br /><br />The "telltale" is just a visual indicator of cooling system function. The "telltale" is the last in line and is basically a cylinder block drain.<br /><br />If there is water coming from it, it is an assurance that the engine block has water in it.<br /><br />There are a couple reasons it may stop.<br /><br />1. Water pump fails.<br /><br />2. blockage. (cooling passages or the telltale passsage itself-which is common)<br /><br />Again, it's just an indicator. If it stops, it's up to you to find the reason.

 

[billinengland]

Re: Cooling on a 1983 Evinrude 7.5 - basic question

DJ,<br /><br />Many thanks for your help and your prompt reply - It's all starting to make sense (sort of).<br /><br />Bill<br /><br />PS - This is a great facility!!