compression question

[reefrunner7]

Just had my 85 johnson v4 compression tested 130,110 100 100 it still runs nice but mechanic says he can hear a knock and gave me total doom and gloom. What would you guys think? am I just trying to get an engine sold to me?

 

[tashasdaddy]

Re: compression question

i would do a decarb, and go from there.

 

[jbjennings]

Re: compression question

I would do my own compression test, or at least see the gauge while it's being tested if I didn't trust the mechanic. Do you hear the knock?
If the compression #'s are correct, and there is a knock, the motor very easily could be on it's last legs.
JBJ

 

[kenmyfam]

Re: compression question

Agree. Re-test it yourself and do the decarb as suggested. Then check compression again.

 

[reefrunner7]

Re: compression question

motor hadn't been run in over 1 year, originally started it up and wanted to overheat, pulled thermostats out and thoroughly flushed it for about 15 minutes, the small air release holes in the gaskets were totally blocked I made them bigger and wire brushed the inside of the thermostat housing's out. Now it no longer overheats and I frankly hear nothing except the motor running and it runs even. Seems like the more I run it the better it gets is that possible? Are there any grease ports on the 85 johnson motor that can be greased?

 

[reefrunner7]

Re: compression question

1985 120 johnson that is

 

[Rick.]

Re: compression question

Seems like the more I run it the better it gets is that possible?
Very possible. DO a decarb like TD suggested. Your rings may be stuck a little and a decarb will clean up the cylinders and rings. By running it more, you doing the same thing but a decarb will do it quicker and better. Best of luck. Rick.

 

[jpwade_bsu]

Re: compression question

mechanic says he can hear a knock

youtube on how to measure/check rod knock

http://www.youtube.com/watch?v=bgfgbpvOFrQ