compression help?bought last week

[greg carr]

hi i have a 1979johnson115 v4 i did a compression test on a very cold moter and the results was 115 85 on one side and 125 125 is this good or bad? the boat seems to run good with lots of power it was about 40 outside and the boat had not been started that day?

 

[LubeDude]

Re: compression help?

Re: compression help?

Warm engine is better, but did you have all the plugs out at the time and a freshly charged battery? That 85# figure is low. You may find that if you do a Decarb that you just may get the compression up on that cylinder!

 

[JB]

Re: compression help?

Re: compression help?

Probably could use a decarb, Greg. If that doesn't even things up pull that head and look for a leaky head gasket.

 

[tashasdaddy]

Re: compression help?

Re: compression help?

agree with JB, i like this method.
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

 

[Bard1]

Re: compression help?

Re: compression help?

agree with JB, i like this method.
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

Q, is it a good idea to do this just to do this. I mean is this a good prevent of maintenance thing to do

 

[greg carr]

Re: compression help?

Re: compression help?

yes all plugs were out best way 2 do de carb?

 

[greg carr]

Re: compression help?

Re: compression help?

do you think this is major or maybe eazy 2 fix

 

[greg carr]

Re: compression help?

Re: compression help?

sould i not run the boat does this sound bad or just not good lol i know that sounds dumb

 

[splitshot]

Re: compression help?

Re: compression help?

Do the decarb as mentioned and then run it for a day or so and see if the compression on the weak cylinder comes back up...that will let you know if it fixes your compression problem