1978 115 Compression got worse

deerhuntre

Petty Officer 2nd Class
Joined
Apr 26, 2007
Messages
186
Top cylinder had 50 psi . The other five have 125 psi. Started the decarbon process and actually only made it through the first 15 minutes, then rest, then about five minutes of the next session and ran through the 3/4 gallon of fuel. There was TONS of white/light-grayish smoke. Serious mosquito abatement, except that it's in the 50's here. :eek:

So, after I ran out of fuel I figured I'd do the compression test. Now I'm getting maybe 20 psi in the top cylinder.

I had the transfer cover off last week and the top piston looks fine on that side. The rings: The top ring didn't move when pressed with a screwdriver. The middle ring springs back just fine. The bottom ring also did not move at all when pressing with a screwdriver.

I'm thinking about refilling my 3 gallon tank with 2 1/4 gallons of gas, three cans of Sea Foam, plus the 2 cycle oil, thereby tripling the recipe. Then I'd perform the full de-carbon process again, but this time I should make it through the three fifteen minute sessions. Then I'll check the compression. The reason I'm thinking this still may help is there was still so much thick smoke when I had run out of fuel that it seems there's likely still lots of carbon build-up inside.

Do you agree/disagree? Any chance in the world it could be carboned up enough to freeze the two rings? I just don't see any other signs of overheating. This is a new-to-me motor.

What else can I provide that would be helpful for advice?
 

cell

Petty Officer 1st Class
Joined
Apr 16, 2009
Messages
208
Re: 1978 115 Compression got worse

I always thought you get better results from doing the cylinder soak,and then running under a load in a lake with the leftover in the fuel tank.
 

deerhuntre

Petty Officer 2nd Class
Joined
Apr 26, 2007
Messages
186
Re: 1978 115 Compression got worse

So I should tilt the motor up as much as I can, make sure the piston is close to TDC so the seafoam doesn't leak out the intake/exhaust, and then fill with Sea Foam overnight or for a few days?

Then go to the lake and run the concoction in the decarb tank in the prescribed increments?

Please confirm this is what you are suggesting. I'll fill the piston this morning before I leave for work.

I wonder if Kano Kroil Penetrating Oil is better or just the sea foam?
 

cell

Petty Officer 1st Class
Joined
Apr 16, 2009
Messages
208
Re: 1978 115 Compression got worse

When I did mine I tilted it all the way.If runs in the engines it ok.Then I just funneled the sea foam in the cylinders.Left it over night,and did it again.Then I took another can and dumped it in the fuel tank.Started it to warm it up then drove out to the launch,and ran it on the water.I never did check my compression(I had good compression before)afterwards....it sounded like it ran better,and after 3 fuel tanks later it still sounds/runs good.
 

daveswaves

Ensign
Joined
Mar 22, 2002
Messages
901
Re: 1978 115 Compression got worse

I had the transfer cover off last week and the top piston looks fine on that side. The rings: The top ring didn't move when pressed with a screwdriver. The middle ring springs back just fine. The bottom ring also did not move at all when pressing with a screwdriver.

The top ring is still stuck, try the seafoam in the top cyl again and let it soak. Seafoam in the tank again and take it for a run on the lake, running in a bucket or on muffs does not load the engine up enough for the rings to pop free.
 

deerhuntre

Petty Officer 2nd Class
Joined
Apr 26, 2007
Messages
186
Re: 1978 115 Compression got worse

Well, its been soaking since this morning and I've poured more into the cylinder and it's going to soak overnight. I may even let it sit until Sunday morning and take it to the lake then. I hope they do pop free!!
 

deerhuntre

Petty Officer 2nd Class
Joined
Apr 26, 2007
Messages
186
Re: 1978 115 Compression got worse

Good news!! I went to the lake and performed the decarbon process and when I got home I checked the compression: 100 psi!!

The only problem, and I think/hope its ok, is when cranking the starter with the compression gauge installed, the engine started. I quickly shut it off, but it wasn't connected to water. Granted, I just got back from the lake and the motor ran for a few seconds at idle, so I hope I didn't ruin my new impeller that I just installed last week!!

Anyhow, I continued to get lots of smoke each time I ran after the 15 minute rest period until running out of concoction, so I'll probably perform the soak/decarbon process again soon.

I did peek at the piston thru the spark plug hole and it looks A LOT cleaner!!
 
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