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Another 1957 (1958) Evinrude 18 powerhead review

S

shinola

Contributing Member
You guys are always helpful (and often brutally honest) and it's helped me learn alot. Here is another 18 powerhead. I picked this up at the AOMCI swap meet a few weeks back and just got around to checking it out. I bought the full motor as a parts motor, very cheap, and really only expecting to get lower unit castings out of it. But I cracked open the powerhead and found some promising things.

1. Compression check before I popped off the head showed 135 on top, and 130 on bottom. This is the highest compression I've found, and this is my 3rd candidate powerhead.
2. Rings all pass the spring test, no visible corrosion anywhere inside the combustion chamber or crank case (only opened the bypass covers)
3. Exhaust side had the least carbon buildup of any I've seen yet, not sure if this means anything, but it was nice to see, less cleaning if this becomes a candidate.
4. Piston skirts are cleaner than any I've seen yet.
5. Cylinder walls look good to my untrained eye.

So some pictures:

Bypass covers.
 
I would still take it all apart for inspection / cleaning.-----Looks like a winner to me.--------Since all the bolts came out I doubt it saw a lot of salt.-----Not properly stored maybe.
 
$65 for the whole motor. Only missing the carb, flywheel, and prop, but I have all of those. Now I'll have to rebuild it as a 58 instead of the 57. The cowling has 1 good medallian and the front plate which is different from the 57. I like the darker colors anyway for the 58.

Now I suddenly have a lot of work in front of me, but it's going to be fun...
 
Any tricks or tips on how to safely clean the water jacket? Also, I'd rather not split the crank case open, if I remove the carburetor manifold and leaf plate, will I get enough visibility into the crankcase for inspection / cleaning?
 
I like Racers advice. This motor should be completely dismantled. The water jacket needs to be physically cleaned out. The case should be opened up, crank seals replaced. Needs to be cleaned of oxidation, assembled with all fasteners cleaned, then LIGHTLY coated with nickel anti-seize. Needs repainted with a zinc chromate primer, then topcoat. Personally I would then epoxy clear coat. Loctite 518, 515, or equivalent, LIGHTLY spread on case halves mating surface. Remember the case half alignment dowels are directional, do not try to push them out the wrong direction. We really want to keep Racer for his guidance.....he's been doing this a long long time.
 
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I had a 305CID Volvo/Penta engine (Small Block Chevy basically) with a water jacket that looked like that. The jacket came clean with a power washer. I quickly dried the block with a towel and compressed air then sprayed it with WD-40 to prevent flash rust.
 
My fear is with the little experience I have I'll do more harm than good. But I want to do this right, so I'll be tearing down as suggested. I do have the first powerhead I bought that appeared to be higher hours. Perhaps tearing that one down first will save me some learning on this good one.


Thanks again for the advice. I'll start a new post once I get started to document the project.
 
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