Thread: 1958 Evinrude 5,5

Get you a hand full of ball bearings and put in tank, every time you walk by it pick it up and give it a good shaking. It will break most of the loose rust loose. Then take a shop vac and suck out all that you can. Also you could find a Harley shop ask them about tank restore products. There are a couple that have a cleaner and sealer for old steel tanks. Take the motor and lay it with spark plug pointing up, remove plug, pour in some penetrating oil. Let this stand over night not a lot, then give it a little more every day for about a week. Then take a socket with a ratchet that will fit nut on flywheel. Just turn it slightly one way then the other. Then more oil. Eventually you will get it to turn all the ebay around. Just keep adding a little oil at a time as you do this. Will eventually clean any rust off cylinder without cracking rings.

Thats what I am doing now. Any specific product you would recommend for penetrating oil? I just put WD40 in it for now. My dad made me shake an old gas tank for days with clean gravel and navel jelly.... but Im too old an kimped uped to shake a gas tank for too long !!!! Any chemicals that will do the job without all the manual shaking???

The best penetrating oil is a 50/50 mixture of ATF and Acetone. This was proven by tests done by a machine shop and published in the Machinist's Workshop magazine. FYI, here is the results of their test.

Pentrating oil / Average load / Price perfluid ounce
None / 516 pounds /
WD-40 / 238 pounds / $0.25
PB Blaster / 214 pounds / $0.35
Liquid Wrench / 127 pounds / $0.21
Kano Kroil / 106 pounds / $0.75
ATF-Acetone mix / 53 pounds / $0.10

The ATF-Acetone mix was mixed 1 to 1 ratio.

We always used "Marvel Mystery Oil". Used to put a t-spoon in cylinders of equipment being stored for the winter or the summer. Removed the plug and rotated the engine several times to coat the cylinder and rings. We always did this on 2 stroke motors.

When we had a stuck ring or my grand father ran into one in his engine shop, he used the same product and similar steps to what Cray mentioned.

If I were you, I would go ahead and pull the head to inspect it since the motor is so old plus visually inspecting it will help in diagnosing any problems. I bet a new head gasket can be had for pretty cheap for that motor.