What is this hole

[Den Grass]

Why is oil coming out of this hole? what is this hole? I got this old 40 hp Big twin recently and I removed plugs and poured a little sea foam in the cylinders and turned the flywheel back and forth to clean the cylinders out a bit. That worked great but then I noticed fluid coming out of the hole. I didn't see it before. Can anyone shed some light on this?

 

[saltchuckmatt]

Why is oil coming out of this hole? what is this hole? I got this old 40 hp Big twin recently and I removed plugs and poured a little sea foam in the cylinders and turned the flywheel back and forth to clean the cylinders out a bit. That worked great but then I noticed fluid coming out of the hole. I didn't see it before. Can anyone shed some light on this?

Normal. Exhaust/water hole leaking years of oil residue that you loosened up with the seafoam you probably didn't need.

 

[F_R]

There is a cavity behind that hole. The hole drains that cavity so water doesn't sit in there and freeze or cause corrosion. Above that area is the exhaust tube. Guess where that Sea Foam went? Yep, out the exhaust ports, down through the exhaust tube, and puddled up in the cavity drained by that hole. At least now you know the drain hole is not plugged up--that's a good thing. Rest well tonight.

 

[Den Grass]

Thanks F_R! I'm feeling better about this motor.

 

[oldboat1]

"old" doesn't identify the motor. 50:1 is the likely mix (about 2.5 oz outboard oil per gallon of gas.) You might want to remove the lower unit and power wash the inside of the leg. Should not need solvents with normal use, incl off season storage.

 

[racerone]

Not sure that power washing inside the exhaust housing is a good idea.----Too much risk of getting water on bearings.

 

[Crosbyman]

check for accumulated crud/sand build up while your check things out
(see a small MErc GC cavity full of junk)
keep that drain open!

 

[Den Grass]

"old" doesn't identify the motor. 50:1 is the likely mix (about 2.5 oz outboard oil per gallon of gas.) You might want to remove the lower unit and power wash the inside of the leg. Should not need solvents with normal use, incl off season storage.

I t is a 64 Evinrude Big Twin. I did mix the gas 50:1. I just got it started today. It started easily but it would occasionally backfire. Do you know the possible causes of the backfires? I will have to replace the impeller since I did not see tell tale.

 

[saltchuckmatt]

I t is a 64 Evinrude Big Twin. I did mix the gas 50:1. I just got it started today. It started easily but it would occasionally backfire. Do you know the possible causes of the backfires? I will have to replace the impeller since I did not see tell tale.

Backfire or sneeze?

 

[Den Grass]

Backfire or sneeze?

Back fire out the exhaust.

 

[racerone]

Open low speed mixture screw 1/4 turn at a time.----Lean sneeze will likely go away.

 

[saltchuckmatt]

Back fire out the exhaust.

Timing usually. Did you run it long and did it get hot?

 

[Den Grass]

Did not run it long. Maybe a minute or two. Did not get hot. I want to replace impeller before I start it up again. What is the difference between backfire and sneezing?

 

[saltchuckmatt]

Did not run it long. Maybe a minute or two. Did not get hot. I want to replace impeller before I start it up again. What is the difference between backfire and sneezing?

Do those have a tell tale?

Backfiring to me, is to much fuel or improper timing. Make sure spark plugs are not fouled and lean it out some. Either way you will need to play with the idle screw to correct it or rule it out.

Lean sneeze makes a different noise and the motor shakes side to side usually. You will know the difference.

 

[racerone]

This sounds like a lean sneeze.-----A mysterious thing that 2 strokes do when not enuff fuel is present.-----No need for a tell tale if water pump impeller is replaced every 5 years.-----The exhaust relief has a steady stream of water coming out at full throttle.----Then as motor cools it settles down to just a mist coming out of the relief.

 

[F_R]

A lean sneeze is when the fuel/air mixture explodes in the crankcase and sounds like a man-sized hiccup. A backfire is when the fuel mix explodes in the exhaust system and goes off with a bang. If it is running, it likely is lean sneezing rather than backfiring.