Mercury 4.5hp (45) 1975 Cooling

[jon8910]

Hi<br /><br />I just bought a 1975 Mercury 45 (4.5hp) outboard. It is in great condition and looks hardly used. It started easily and I ran it for maybe a couple of minutes. Only a mist came out of the cooling water outlet which said 'fresh water flush' next to it. Should there be a stream of water from this motor? I thought I read somewhere that there should be only a mist but now can't find that in the Seloc or owners manual. Do I simply undo the two nuts which appear to hold the foot onto the stem to get to the water pump. The Seloc is not clear at all, it jumps around. I guess I don't need to pull the propeller off. Thanks in advance.

 

[Laddies]

Re: Mercury 4.5hp (45) 1975 Cooling

Ck to see the tell tail is not pluged if is open, you need to ck the imp. yes the 2 nuts will remove the foot

 

[jon8910]

Re: Mercury 4.5hp (45) 1975 Cooling

Thanks for that. I pulled the foot off and the impeller looked ok but I will change it. I put a rubber pipe on the copper pipe in the stem that the plastic pump output connects to and blew. It seemed blocked. I then pulled off the tell tale pipe and blew back through the engine and it seemed clear although the air wasn't coming out of the copper pipe at the bottom of the stem, I put my finger over it and I could feel nothing and it was clear when I blew. I also sucked the tell tale pipe and it was clear. Can I undo the six nuts to remove the power head from the shaft and lower cowling to get to blocked waterways? And can I leave the flywheel, carb etc. on. Or do I have to strip all from the top down to get to the waterways. Finally, is there a particular place that usually blocks? Thanks in advance.

 

[dajohnson53]

Re: Mercury 4.5hp (45) 1975 Cooling

OK, I think we might have more than one thing going on here. I don't know if this applies to your 4.5, but it does apply to my 9.8 of the same vintage, so check it out to see.<br /><br />The "fresh water flush" should not be an opening, but a port with a screw in it during normal operation. There is an opening that should be streaming water, called the "tell tale", but that is not normally labeled. Maybe on your engine, theY tell tale opening is near the flushing port and it appears that the label applies to the tell tale? Is there a screw in that same vicinity?<br /><br />If the screw to the flushing port is missing, you should replace it. Although I'm not totally familiar with the water passages, I'm thinking that if that flush port is open while the engine is running, it is diverting water from the normal cooling system.<br /><br />The tell tale should have a steady stream, maybe stronger at higher RPMs. The advice you've received sounds good re: removing the foot. If you're having trouble using the Seloc, consider buying a factory shop manual. I have both and find both have their good and bad points. Maxrules.com has the manuals.

 

[jon8910]

Re: Mercury 4.5hp (45) 1975 Cooling

Thanks<br />You're right although I still have the problem. My tell tale is right next to a blanked off flush port labelled flushport. The mist was coming out of the tell tale so everything was in the right place. For next question see below.

 

[jon8910]

Re: Mercury 4.5hp (45) 1975 Cooling

But this doesn't mean I don't have a problem. The flush port screw is in place. What is the easiest way to investigate blocked waterways from the description above? Again, thanks in advance