new compression numbers

boomtime

Cadet
Joined
May 7, 2008
Messages
24
well i cleaned some seaweed out of my intake today and then took a test run with good results. motor is runnin good.

so i got back to my dock 20 minutes later and remembered that i wanted to do another more accurate compression test with the advice you guys gave me before. as in take all the plugs out and test a warmed up motor so the rings are sealing.

5 revolutions or so about 3 solid seconds of cranking per test:
100 - 103 - 103 - 119

i also noticed 1 of the plugs looked fine, 1 looked like it had rust caked on it that i scratched off with my fingernail and the other 2 had this white stuff caked on that i also was able to scratch off and those 2 were on the same bank.

i know white means lean normally but this almost seemed like corrosion to me that could be wiped off, same with the rust colored buildup on the other plug.
 

tashasdaddy

Honorary Moderator Emeritus
Joined
Nov 11, 2005
Messages
51,019
Re: new compression numbers

if water was getting in it would look steam cleaned. you definately need to do a decarb, and see if you can get the 3 cylinders compression up.
 

tashasdaddy

Honorary Moderator Emeritus
Joined
Nov 11, 2005
Messages
51,019
Re: new compression numbers

Decarb, take a can of seafoam put 3/4 of it in the gas tank, with only 1 gallon of premixed gas. put the rest in a spray bottle. start the engine, and let it come up to temperature. then remove plugs, and them some real good shot of seafoam into the cylinders, replace plugs, let sit 15 minutes. restart, and spray the rest of the seafoam into the carbs, so the the motor almost stalls, wait and repeat until the seafoam is gone.then take for a wide open spin. then put in new plugs, ad premixed gas to the tank, and take it for a wide open throttle spin. it is going to smoke like a house on fire, during this process.

afterwards compression.recheck
 

boomtime

Cadet
Joined
May 7, 2008
Messages
24
Re: new compression numbers

should i be taking note of how the engine performs during this process or it doesnt matter? also should it run like poop or good during this process from your experience?
lmao @ house on fire.
 

tashasdaddy

Honorary Moderator Emeritus
Joined
Nov 11, 2005
Messages
51,019
Re: new compression numbers

idle is fine, for the warm up, and to use up the spray sequence. then take it out and run the poop out of it. also don't do it on the clean driveway. it will look like the motor had diarrhea. which is what you want. ever feel kinda sluggish and stuffed up. a little laxative, will usually take care of it. this is the same thing for your motor.
 

boomtime

Cadet
Joined
May 7, 2008
Messages
24
Re: new compression numbers

well the boat is gonna be in the water that isnt a problem right?
 

tashasdaddy

Honorary Moderator Emeritus
Joined
Nov 11, 2005
Messages
51,019
Re: new compression numbers

no, just don't do it in the marina, the neighbors won't like the scum on their hulls, and the smoke.
 
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