1992 mercury 40 pissing hot water/steam

spencer321

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Joined
Jul 24, 2013
Messages
10
I have a 1992 mercury classic inline 4 cylinder. There is no thermostat, when first cranking the motor it takes quite a while for the pisser to start, 30-45 seconds, and is very hot. I would think with no thermostat that it would be cool at first. Im getting a heavy solid stream from the pisser so I dont think its the impeller. The last time I had the boat out it got really hot and was pissing steam so I shut it off immediately and paddled it in. When I got home I hooked up the muffs and it pissed just fine but again hot.

what could be causing it to take so long to **** and running hott and overheating?
 

plazmore

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Jul 22, 2005
Messages
28
Re: 1992 mercury 40 pissing hot water/steam

I have had this happen a few times...did you by chance just change the water pump? have the lower unit off to inspect? it can be challenging to get the tube mated up into the motor correctly...also, if the motor has run dry, even for a few moments, the outer diameter of the pump gets melted, thus reducing water flow and cooling...another time, I was sold the wrong pump, and when swapped, all was cured...thirdly, I had some chunks of stuff blocking the tube, reducing flow...a byproduct of use in saltwater with lots of crud around...another could be the impellor blades bent the wrong direction upon installation....hope this helps...

I am not an outboard doctor, but I did stay at a holiday in express...
 

spencer321

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Joined
Jul 24, 2013
Messages
10
Re: 1992 mercury 40 pissing hot water/steam

So I got the lower unit off, and as i suspected the water pump looked fine, impeller was in good shape, but there looks to be sand everywhere, the water pump itself wasn't loaded with sand, but all around it in the top of the lower unit has evidence of sand. The plate that the exhaust pipe attaches too is covered in sand, I believe I have sand impacted in the motor... how do I go about getting sand out of the cooling passages?
 

spencer321

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Joined
Jul 24, 2013
Messages
10
Re: 1992 mercury 40 pissing hot water/steam

Ok another update, hooked up the air compressor to the pisser and there was very little air pressure coming out of the copper tube. So i hooked up the hose and backflushed it and instead of water coming out of the copper tube (some did) it appears to come out the lower end in every direction? please help I don't want to take this thing to a mechanic and get raped
 

spencer321

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Joined
Jul 24, 2013
Messages
10
Re: 1992 mercury 40 pissing hot water/steam

One last update before I give up for the day, I backflushed the motor with water, then 50/50 vinegar water, then more water. Inbetween each flush I took some weed wacker line and pushed it in as far as it would go, each time it went a little further. The final time I must have gotten 7 feet of nylon line into the pisser outlet, never saw it come out the bottom tho. Hope this helps someone to help me. Thanks in advance
 
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