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1957 18hp Fastwin powerhead take 2

S

shinola

Contributing Member
I've found another potential powerhead for use on my 57 Fastwin. It's local and I have the opportunity to check it out before buying. It's advertised as a freshwater only motor with 120 PSI per cylinder. I have a couple of questions:

1. I'll verify the compression, but haven't done this on an old outboard like this before. What's the procedure? Do I lubricate the rings before checking? If so, with what? Any particular advice on how to perform the test with the powerhead off the lower unit? What's good enough compression?

2. What else should I verify? I've read other threads on the board describing a "leak test" to verify rings are not frozen to the piston (?) Any other inspections you would recommend?

Thanks!
 
it is difficult to do if not held down somehow and a flywheel installed so you can rope it over. A spritz of WD-40 is OK, but a blast of thick oil is cheating. Not a thorough test, but remove the intake bypass covers for a non-invasive visual check for stuck rings, rust, etc.
 
I posted pictures of the powerhead I got off of ebay a few weeks back that was in poor shape. Several folks commented on the pistons, skirts, and cylinders appearance. Would anyone have a good example of a "good condition" piston, rings, cylinders, etc to use for comparison?

And how do you verify rings are not stuck? Is it just visual?

I also think I should pop off the head and get a good look at the cylinder walls and the water jacket. Any downside to doing that?
 
I bet I could mount it to the 3 studs on my lower bracket to hold it for the compression test. Anyone every spin one with a drill for compression test?
 
shinola said:
I posted pictures of the powerhead I got off of ebay a few weeks back that was in poor shape. Several folks commented on the pistons, skirts, and cylinders appearance. Would anyone have a good example of a "good condition" piston, rings, cylinders, etc to use for comparison?

And how do you verify rings are not stuck? Is it just visual?

I also think I should pop off the head and get a good look at the cylinder walls and the water jacket. Any downside to doing that?
Click to expand...

With the port covers removed, you can poke the rings with a screwdriver or similar tool to see if they spring in & out. Also look for excessive carbon, scoring, rust, whatever. As for pulling the head, that's between you and the seller. Personally, I probably wouldn't allow it. If you don't buy it, he is stuck with a powerhead that at the least needs a new head gasket, and possibly some busted off head bolts. After all, it is a very old motor.
 
Step 1: Compression check.

So I performed the check. Here's the results: Top cylinder 125psi, Bottom cylinder 110 psi.

So in reading, it seems the desired results are over 100psi with less than 10% difference between the cylinders for old 2 strokes.

I fail the 10% difference. What would happen if I buy this and fire it up?

thanks...
 
It will run.-----May not run as well as it could.----One of those 22 cubic inch motors ( 57 or a 76 model ) in good condition will idle so nice that you might not want to shut it off.---Not sure where this 10% difference comes from.------Motors are now made in an environment where all the parts are the same.----So remove those bypass covers to have a peek at the rings / pistons.
 
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Thanks racer. I've watched enough youtube videos to be dying to get this thing running. I'll still open up the intake side to get a look at the rings and pistons.
 
Step 2: Bypass covers off for piston/ring inspection:

Top cylinder: Top 2 rings are free to spring in/out and have no appearance of rust. Bottom ring (skirt end) either is stuck or has suck little motion it's hard to perceive. I think I got it to move a small amount, but I'm not sure. Skirt end of piston has some scoring marks. The intake port is very dirty and the bypass cover shows signs of rust I think.

Bottom cylinder: All 3 rings move freely, but the bottom ring (skirt end) is black in appearance. The intake port appears a little cleaner, but still kinda dirty.

Bypass covers: In picture, the one modified for pulse pump was on the top cylinder. It shows some signs of corrosion.
 
Once again.------I would take that engine apart for a complete inspection.-----It takes longer that 1 HR to really understand these old power heads and what happens to them over 60 years !!!
 
That motor has had water in the cylinders/crankcase. Fatal to the bearings if they are affected. It MIGHT be repairable, no way to know without taking it apart. But at this point, I don't give it much hope. It would have to be mighty cheap for me to spend my money on it.
 
Agreed. Water got in and possibly through the intake side...either way, bearings are susceptible. If rust or pitting is present, then it's likely a no fixer. Why can't people put these parts someplace dry? I have so many motors here destroyed from improper storage.....and it wasn't me. Even outside....in an old van, they last for years.
 
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