1975 25 hp Evinrude 25502B

KC9000

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Bottom of lower crankshaft seal. There is a small knick in it....
 

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racerone

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Face shown in pictures post #21 goes against the bearing.-----I would call that the TOP of the seal.-----Post picture of the bottom crank bearing as installed in this motor.----It can only be installed one way !
 
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KC9000

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195928 pic was facing the bearing. 155508 was facing the spring and that is fuel mix on that side of the seal.
I will post pic of bearing as soon as I get home. Thanks again for you time and reply.
 

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racerone

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The carbon rotates with the crankshaft.----The raised face in 195928 runs on the bearing face.-----A very minute amount of liquid is allowed to leak out.----This lubricates the seal.----That is how a mechanical seal works.----Have had experience with mechanical seals that sealed 1000 PSI in a D2O ( heavy water ) systems.
 

KC9000

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165738 was the way the bearing was and was correct. 165741 is the bearing.
 

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KC9000

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Would the baffle gasket leaking cause that idle issue? Or the missing drive shaft oring? Or the damaged waterpump grommet?
 

KC9000

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Well had to be done. I will swap carbs after it together and see if it's that
 

Crosbyman

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KC.. lack of fuel to run at idle possibly caused by some air leakage causing a reduced vacum pull on the idle chamber fuel supply (assuming all is spotless clean in the carb)
See this UTUBEs (Dangar) used a propane fuel supply to poke around the engine power head the idea being propane will be ingested at the leak point and stabilize the idle for a few moments thus proving the issue being air being sucked in somewhere instead of fuel from the carb .
see if you can find a vacum loss

btw try tilting the engine up or down a bit see if that make a difference.
check real closely for airline cracks on the carb surfaces.
 

KC9000

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@Crosbyman I Will be trying that for sure when back together, I don't have the lean sneeze tho, or maybe a form of that? What's happening to this motor is when I back the throttle down to its Lowest, the engine just dies. No sneeze, just dies. Ican make it sneeze by adjusting the low speed needle to lean.
Engine surging
Engine at its best settings I could get. It's to high in rpm for idle though, I had the link set to have the throttle valve stay open a smidge cause as soon as it closes the engine dies.

A little history on the engine as what I found when I acquired it few weeks ago. The crankshaft flywheel Key was sheared. It had rubbed the driver coil and magnets on the flywheel has minimal scaring. It did not look bad but it was what caused it to stop running. Also there is a chip out of the crankcase collar at the top. It is above the seal. I will test for a leak there but it is clean up top and I have seen leaky ones and you usually have some residue in that area.
Found this on the net that I will be going through. I've already did compression and attached test results. Carb was cleaned and I luckily have another to try. If no change I will go to reed valves and check those. I will replace the lower cs seal. Might do the top seal just for restoration purposes.

The engine could have any one of a number of things wrong with it. It could have low compression, bad crank seals, bad labyrinth seal, bad reed valves, dirty or misadjusted carb, bad fuel, bad plugs. You always start with a compression test. For results you are looking for 90 PSI or more, anything less is a fail. After that make sure all fuel is 100% brand new, no mix of new and old fuel. If that is good, run the engine and place your palm over the throat of the carb, you must feel suction at all times, if you feel any pressure or fuel spitting back at your hand, the reed valves are bad. If no change, run the engine on a 25 to 1 premix ratio (5 ounces of oil per gallon of fuel) If the labyrinth or crank seals are bad, what will happen is the oil will help seal those leaky seals. If the engine reacts by running better, or of the coughing is less, the engine has bad crank seals or a bad labyrinth seal on it. If that makes no difference, then you are likely looking at a dirty, misadjusted, or simply a bad carb that is leaking down internally.
 

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Crosbyman

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any chance the throttle handle skipped a tooth or 2

my 9.5 will die the same way but... the side idle limit adjustment keeps the throttle from going to far (low) by blocking the linkage which prevents the engine from dying. it will idle fine all day .

your engine does seem to idle down enough being a 25hp.
 

KC9000

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Yeah I had it set pretty good in that 2nd video. I had the idle adjustment set to the lowest I could go with out it dying. But had to have the throttle valve open a smidge to keep it going. I am gonna check vacuum leaks and carb swap and test. Got parts on order to address the baffle gasket, driveshaft oring, water pump grommet, lower crankshaft Seal, and lower cover seal. Gave me the opportunity to clean it really good too. She will be beautiful when done. I will get this idle thing figured out and when I do that will be a hot motor....lol
 

KC9000

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Yeah I had it set pretty good in that 2nd video. I had the idle adjustment set to the lowest I could go with out it dying. But had to have the throttle valve open a smidge to keep it going. I am gonna check vacuum leaks and carb swap and test. Got parts on order to address the baffle gasket, driveshaft oring, water pump grommet, lower crankshaft Seal, and lower cover seal. Gave me the opportunity to clean it really good too. She will be beautiful when done. I will get this idle thing figured out and when I do that will be a hot motor....
 

KC9000

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Anybody know what this paint color code is or the name of it? For the blue?
 

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KC9000

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Being curious and wanting to check the reed valves. I took them out and this is what I found. I am sure this is the idle issue. As it seems like it's getting too much fuel when throttle closes to idle. Check out the pic and give me your thoughts. You can see light on those two holes and there is 1 more with same issue same side. The other side is light free.
 

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