"Motor is a 1973 20" v4 Jo
"Motor is a 1973 20" v4 Johnson 115. I bought a new guage to check compression to evaluate replacing the motor that was on a recent boat purchase. I got 122, 135, 135, 148. I know the variance is not good, but the 135s and especially the 148 seems way too high. I did the test right after doing a decard with seafoam.
Have not done this before, so this was method; removed all plugs, advanced throttle to WOT, checked each cylinder with plugs out of all of them. Did not do any calibration on guage, just right out of the box.
For what it is worth, the motor has corrosion on the bolts to such a degree that I am not confident I have the ability to get the heads off without creating more problems than I solve."
"Motor is a 1973 20" v4 Johnson 115. I bought a new guage to check compression to evaluate replacing the motor that was on a recent boat purchase. I got 122, 135, 135, 148. I know the variance is not good, but the 135s and especially the 148 seems way too high. I did the test right after doing a decard with seafoam.
Have not done this before, so this was method; removed all plugs, advanced throttle to WOT, checked each cylinder with plugs out of all of them. Did not do any calibration on guage, just right out of the box.
For what it is worth, the motor has corrosion on the bolts to such a degree that I am not confident I have the ability to get the heads off without creating more problems than I solve."