50 hp cooling question

[1408gmac]

I'm a new member. I hope you can help me with this question. <br /><br />I have a 2003 Merc 50 hp. Very very low hours. I ran it briefly in slat water in unfamiliar waters and got some sand in the cooling system. I did not overheat at all - was very close to the launch ramp and knew it when I did it. The pee hole line was clogged. I cleaned it out. Seemed to be cooling okay after that.<br /><br />Now, it seems that the pee hole stream is weak. Maybe I'm just over sensitive now. At low rpm, it still puts out a weak stream, but I would say maybe at half the velocity when running at a higher rpm. And, sometimes, its much stronger, even at a low rpm, and then seems to weaken.<br /><br />I checked the impeller. It looks like new. I inspected the thermostat. It looks clear and clean. I blew air through the cooling system backwards.<br /><br />Any suggestions? Could this be poppet related? I don't know much about those. Should I check them for sand? Where are they?<br /><br />Any help much appreciated.

 

[andrewkafp]

Re: 50 hp cooling question

Welcome to iboats.<br />You may be in luck as I have a 2005 Mariner 50 which had the same identical issue. These new motors have a few modifications on them such as an extra water pickup under then cav plate and a high volume low pressure impeller. This means not much water on the muffs at the best of times,unlike thye older models which had 2-3psi at idle.<br />What you need to do is insert some plastic line from a weed whacker into the telltale while running. As the pressure is low, it will remain in there and seem to be clear when you blow in it, but this combined with water flow should clear it.<br />There is most likely no problem with it and the cooling system is still working fine except low indicator flow . I made a special set of muffs out of 2 sets with a hose inlet both sides to increase water flow.

 

[1408gmac]

Re: 50 hp cooling question

Stacer, thanks a lot for the reply. I have had the telltale rubber hose and plastic outlet of the telltale totally off and cleaned out a couple of times. I am pretty sure they are both clear, but, I have not used weedeater line - I'll do that to double check. <br /><br />And, it acts the same in the water as it does with muffs. I saw, but did not really think about the other pick up under the cav plate - thanks for pointing that out. <br /><br />I'll post back after running the weedeater line through the telltale and hose.<br /><br />Thanks for your help.

 

[andrewkafp]

Re: 50 hp cooling question

Mine is 2 hours old and the stream has stopped while ploughing through weeds and mud at low tide twice. They are not a powerful stream, so even a bit of weed will make them slow up, but will not overheat the motor,as the water is still passing through the block and back down through the prop. When running, is the stream hot or just lukewarm ?<br /> http://www.ausfish.com.au/chat/uploads/outboard_flusher_1.jpg

 

[Laotzu]

Re: 50 hp cooling question

I have a 50hp, a bit older....'91. Must be something about 50's, but I did the same thing with mud. I cleared mine by spraying with a garden hose into the intake vents at the bottom of the lower unit without the motor running. Then, once I got a stream out the pee hole, put the muffs on and ran the motor for about 5 minutes to make sure it was clear.<br /><br />My 50's poppet is on the upper left side of the block as you face the back of the motor.<br /><br />Jerry