A mechanic car friend of mine told me it would be easier to test for lower unit leaks by using a smoke test. Will this work. Also I can't seem to find the link on test for leaks. Pressure and vacumn. If vacumn- long much and how long. Thanks
The best thing to do is both a pressure and vacuum check due to the back to back seals in a lot of gear cases. Normally 14 psi pressure and 14 inches vacuum for about 20 min. At the same time rotate the g/c over also moving the shift rod for different gears. Any drop in either gauge readings get out the soapy water.
By rotating the the g/c over you are putting it through it's rotation as when running. Same way with shifting it, you are checking the shift rod seals. I've see g/c's where you test them and they show no leaks. Then you rotate them and a leak shows up.
Rotating the gearcase = manually put the lower unit in gear and rotate the drive shaft or prop shaft to make all of the gears and shafts move in the housing.
First off, do as Daviet says above, if you have a pressure & vacuum tester. If you have the equipment to do this then drain the g/c oil before proceeding and test it. If you don't have the testers and don't want to spend the money on them (which I don't blame you) I would recommend you take it into a good Evinrude dlr and have it done. Hope this helps.
First off, take out the spark plugs then make sure your ignition switch is in the OFF position. Now put your pressure or vacuum tester on it and pump up to the right spec. Put in fwd or rev and rotate flywheel over by hand watching the gauge to see if it drops or not. After that rotate the prop shaft and shift it to see if the gauge also drops. If it does, get out the soapy water and check for bubbles. if you can't find any it might be the upper drive shaft seals and the g/c will have to be pulled to check.
I've done with the lower unit still attached to check the propshaft seal after removing fishing line from the propshaft seals. Just put the engine in a test tank.
