Tank testing...lots of oil??

[cp4000]

Hey guys,
I'm done tank testing my 1976 70HP Evinrude in half of a 55 gal plastic drum. After a total of about 5 hrs of running...There is a 1/4" layer of sludge on the entire top of the water? Could this be gear oil? Oil burned from the gas? I have just replaced impeller, filled lower unit prior to running. The sludge is dark and smells like exhaust. I dont think fresh gear lube would be that dark already....Can it produce that much sludge from the oil in the gas? It does smoke pretty good so maybe I added too much oil? I did check cylinders to make sure all were firing and it is running well? Any input would be appreciated

 

[cp4000]

Re: Tank testing...lots of oil??

I do have a service manual but it does not give quantities. Approx how much gear lube does the gearcase take?

 

[mables]

Re: Tank testing...lots of oil??

What ratio did you use when mixing the fuel?

 

[cp4000]

Re: Tank testing...lots of oil??

50:1...The oil in the tank just seems pretty thick. I guess I have never tested a motor that long in stagnant water? Normal?

 

[samo_ott]

Re: Tank testing...lots of oil??

That's normal. 1/4" after 5 hours is not bad. I almost get that with my 50's engines in half an hour! I use a bilge sock (from sailboat bilges) in the barrel to soak up the oil. It works well. I also use fully synthetic tcw3 oil as it's biodegradable. Then dispose of it. Any particular reason you ran the engine for 5 hours in a barrel?

 

[cp4000]

Re: Tank testing...lots of oil??

Well, I just got the boat / motor and getting it ready for its maiden voyage. The 5 hrs are probably over a three week period where I have been testing various things...Installed a pee hole, getting tach to work, tried to get original amp guage to work, bought a new amp guage and gave up...moving to volt guage, and getting temp guage to work and checking t-stat. So basically just alot of testing. Put a new steering cable on today, raised the motor to its highest position and should be ready to drop in the water next week

 

[Haffiman]

Re: Tank testing...lots of oil??

It might give you an idea why authorities do not want you to use that engine in a drinking reservoir.
Most of the 2-stroke oil does not burn off, but goes unburned out with the exhaust.