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1970 EVINRUDE 4HP MODEL 36

athlon_oved

New member
" I just bought this motor abo

" I just bought this motor about 3 weeks ago. At first it took me about 10-20 pulls to get the motor cranked. I took to a local boat dealership/servicing place and they found that the carburetor needed rebuilt. After I got the motor back today I took it out and it cranked on the second pull. It ran great for a while, probably 10-20 minutes or so. Then the motor over heated and shut off. After it cooled down I cranked it again, needless to say it shut off after a few minutes. After I got it back home I took it to my shop pulled the foot off of it to see if it was the impeller. It seemed to be all right, but I?e heard just because it looks new doesn? mean a thing. As I was inspecting the impeller I noticed a small gap between the impeller and the wear plate at the bottom. The gap looks to be around .001 to .004 thousands wide. Is this normal?
Also I hooked up a small hose to the little tube that runs up to the motor block and tried to blow through the tube to see how easy it was. There was quite a bit of resistance. Is this normal?

I hope that I have explained myself good enough for someone to help me. I'm new to these things and any help would be greatly helpful.

The water comes out of the same 2 rows of holes that the exhaust comes out of. "
 
"Athlon... Having the carburet

"Athlon... Having the carburetor rebuilt was the normal route, especially with a small engine. When they sit for a month or more, you can expect the carb to clog up somewhat. Sometimes a person gets lucky and the carb will clean itself out but that's few and far between.

The double row of holes in the exhaust housing is where a telltale spray of water comes out with the exhaust as you mentioned. However you can still have a overheating problem as you've found out.

A word of advice.... don't try to diagnose exactly what is wrong with the water pump. Just install the complete water pump kit and be done with it. If there's any gaskets involved, use the liquid gasket sealer that's found at any reliable auto type store... the sealer that has a small brush attached to its screw on cap. On any surface that does not have a gasket, use a sealer called "Marpox 1000". Marpox makes other sealers, use only the #1000. A sealed pump will not draw in air, just water as it should!

The restriction at the water tube.... use pressurized air. If that meets with a restriction, remove the cylinder head in oder to inspect and clean the water passages. Even if the air pressure test checks out okay, be sure to check and tighten the head bolts.

Even with a new water pump and clean water passages, a engine can overheat if a head gasket is very slightly flawed. This would enable exhaust pressure to enter the water passage and cause a stalemate when it meets the incoming water pressure, in which case the water can travel no farther, so it sits there and boils. You could take a compression test amd carefully inspect the s/plugs for traces of water if this is suspected... but the only way to really ease ones mind as to if this is happening or not is to remove the cylinder head and inspect that area visually.

Joe
"
 
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