1970 4 hp Evinrude stops suddenly

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clemsonfor

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twocyclemania said:
Thanks to everyone for their replies and suggestions! Solved some of the problem but not all. Did a new head gasket, compression test (70 both cylinders). Discovered both ends of the hose from the fuel pump to the carb were leaking. Probably why it shuts down suddenly; after the initial bulb squeeze fuel is gone. As for the overheating; ran it with the prop off (in barrel) and it's still overheating. The head is hot (sizzles water). Was going to use the infrared thermometer on the block as suggested but splashed some water on the block and that also sizzled. Gotta be well above the suggested 165 degrees. Odd thing is that the exhaust/spray mix coming out the leg holes is not very hot. It's very comfortable to the touch. Popped the flywheel and the coils look great and dressed the points. The motor does have good spark. With all the suggestions and what I've eliminated I think I"m going to have to pull the powerhead and check out the water tube and top grommet. Any other ideas and I'll check them out. Once again, everybody 'thanks'
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Does this motor have a thermostat?
 
C

Crosbyman

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Engine has severe prostate problem...surgery is needed to find the blockage

solution is identical.

painfull but effective.
 
R

racerone

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Thirty five years ago I tried a sierra impeller on a little 2 HP Johnson.-----Took it out and tossed it in the garbage.
 
oldboat1

oldboat1

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Remove the cylinder head and gasket (order a new gasket). Use a hacksaw blade or something similar to clean out the water passages in the powerhead, and clean passages in the cylinder head as well. Reassemble and test run in a barrel, water about half way up the shaft.)

An infrared gun should show no more than 140F at the top of the head when warmed up.

If still overheating, remove the lower unit and make a snug connection between the garden hose (use of the male end of a quick hose release works well, along with some fuel line stepped down to fit the water tube. Run water at about half pressure to flush passages. In the lower unit, make sure that water intakes are clear.
 
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twocyclemania

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Been a while but with winter this motor was one of my projects. I pulled the exhaust cover and found that the small hole at the top of the 'cooling' chamber was plugged; with what I don't know but I would describe it as brown ceramic/mud. Really hard. I ground it out and now it should be able to allow for a flow through the chamber. I'm waiting for a gasket to arrive and I'll give an update then. Also, the pistons/rings from what I could see look great. Here's hoping this is/has been the problem. Thanks 'all' for the input and help.
 
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twocyclemania

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twocyclemania said:
Been a while but with winter this motor was one of my projects. I pulled the exhaust cover and found that the small hole at the top of the 'cooling' chamber was plugged; with what I don't know but I would describe it as brown ceramic/mud. Really hard. I ground it out and now it should be able to allow for a flow through the chamber. I'm waiting for a gasket to arrive and I'll give an update then. Also, the pistons/rings from what I could see look great. Here's hoping this is/has been the problem. Thanks 'all' for the input and help.
Click to expand...
 
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twocyclemania

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Forgot to mention: Odd thing is that the chamber and the head and areas beyond are all clean and there is no corrosion. Don't understand how this hole would be plugged (though it is small). Don't know engineering but you would think they would have had a larger hole unless they wanted the motor to run warm for cold climates.
 
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Crosbyman

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twocyclemania said:
Forgot to mention: Odd thing is that the chamber and the head and areas beyond are all clean and there is no corrosion. Don't understand how this hole would be plugged (though it is small). Don't know engineering but you would think they would have had a larger hole unless they wanted the motor to run warm for cold climates.
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can you post pictures ??? did you pull the cyl head and check the water jacket for crud and the water entry and exits .
 
rolmops

rolmops

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Did you check the pipe that goes from the pump into the engine block for blockage? Did you make sure that the rubber boot at the block is present ? and did you make sure that the water cooling copper tube is fully inserted both in the pump and the block? Last but not least. Did you make sure that the water inlet below the water pump is clean and did you have the lower unit far enough down in the barrel so the pump is under water?
 
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twocyclemania

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rolmops said:
Did you check the pipe that goes from the pump into the engine block for blockage? Did you make sure that the rubber boot at the block is present ? and did you make sure that the water cooling copper tube is fully inserted both in the pump and the block? Last but not least. Did you make sure that the water inlet below the water pump is clean and did you have the lower unit far enough down in the barrel so the pump is under water?
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Pipe is clear as I ran a stainless wire through it. There is no rubber boot at the block. It has a threaded 'compression fitting.' Inlet clean and deep in the barrel. thanks
 
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twocyclemania

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twocyclemania said:
Pipe is clear as I ran a stainless wire through it. There is no rubber boot at the block. It has a threaded 'compression fitting.' Inlet clean and deep in the barrel. thanks
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Anybody think it could be what I described; the plugged coolant flow exit for the cooling water at the (hole) at the top of the exhaust? Will let you know as soon as I replace the gasket and fire it up. thanks
 
rolmops

rolmops

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I have a crazy question,but it may be the key to your problem. When you slide the impeller down the driveshaft there is a small piece of metal that seats onto the driveshaft . It locks the impeller in place. Without it, just a tiny bit of water will make it to the engine and the engine will overheat. Also ,when you inserted the impeller into the water pump, did you turn the drive shaft clockwise?
Sorry for asking these seemingly stupid questions, but I am a firm believer in the step by step approach, starting with the cheap steps first instead of throwing money at it first.
 
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T

twocyclemania

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twocyclemania said:
No I didn't drill it out. I twisted a drill bit by hand just to clean out the buildup.
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Thanks everyone! It's up and running and cooling nicely now. At first I though it must be some other problem as it was still overheating. I did notice that (in the barrel) a lot of water that stayed cold was coming out the leg holes even though the block/head were getting extremely hot. I thought I had managed to get the water pipe into the pump when I put the power head on but obviously not. Dropped the lower unit and sure enough I missed. I should have dropped the lower unit from the beginning.

Seems that the little hard buildup (brown - probably dried mud) that blocked the exhaust cooling chamber exit hole (on top) was the problem all along. Running great now! (I'm going to start a new thread about the recoil - another story). thanks!
 
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