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Evinrude 50hp overheats

5

56350

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I am trying to get our family boat back in the water after over 30 years of inactivity. The boat and engine our in surprisingly good shape. They have approx. 50 hours on them since new in 1971. The problem is that after about 5 minutes at idle, the overheat horn sounds. I have replaced the impeller and thermistat. I have ordered a new pressure relief valve, but I feel like I am just throwing money at it. I did verify the head temperature at 170 df when the horn went off. Any suggestions? Thank you in advance.
 
Is there water from the tell-tale? Did you check the water inlet openings? After 30 years, little critters like to make nests inside openings, and could be stopping water from coming into (or out of) the pump.
 
When I replaced the impeller to the water pump, I checked all the passages for debris and they looked clear. I am pretty new at this boat thing, so I'm not sure what you mean by "tell-tale". When the engine is running, there is a stream coming from the front of the portion above of the foot. I may just pull it all apart again and start from scratch. There has to be some reason why the flow is either not being pumped, is leaking, or is restricted. If the past is any predicter of the future, it is something simple that I did not catch the first three times.
 
The tell tale is a stream of water coming (or should come from) the lower cowl of the motor. On that motor , if its the same as a 72, it should be near the right rear of the engine, a small tube that exits out the side, about 3 - 4 inches below the cowl joint. The water coming from above the gear case (foot) is normal, but if there's nothing coming out the top, then there's nothing going thru the powerhead. Find the small tube, poke a thin wire into it, and see if it's clogged. Spiders and other insects like to nest in there.
 
Are we sure that a 71 - 50 HP would have an indicator in the lower cowl ????-----------------It appears that the factory installed those in 78 and later models.
 
I looked it up on YouTube, and saw a video demonstrating a proper functioning telltale. I will check next time I run. I will also check maintenance manuals, to see if it is described there. Thanks for the replies.
 
Racerone..I think you are right. I'm confusing a 72 with an 82. The 72 (I haven't looked at in about 2 years) I think just outlets the water thru the 2 exhaust ports midway down the leg?? I know the 82 has a tell tale, I had it running last week.
 
Update: Checked pressure relief valve, don't see how this could be the problem. Looks brand new and moves freely. Removed lower unit, removed impeller housing and impeller. Impeller rotates freely when shaft rotates. Connected water muff attachment. Water flows through that area of water pump freely. Checked tube that connects water pump housing to water jackets on head, no obstructions. Started engine with water muff attached, no flow coming from water outlets at base of leg until I presed water muff to keep pressurized water from hose into water intake. This is the only way to get water to flow up to the head. I also submerged foot in a large garbage can full of water with same results. No flow and motor temp climbs. I use a laser thermometer to verify temp. What else can I do other than send to shop?
 
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