I just ran did a compression test on my 62' 40 hp evinrude. Model # 35531. I understand it is supposed to be even in both and around 90 psi. I had 46 and 48. I used the pull starter, would this make a difference?
Does it have electric start? If so, try that. Pretty hard to pull a 40hp motor and get representative compression. At least they are about the same both cylinders.
I tell yah, I couldn't get more than 70 psi on my '62 28hp. It's a hard pull, and I almost tipped it over the stand, LOL!
They say it's easier to pull when it's on a boat. I haven't tried that yet though.
Well, I hooked up battery and got it to 58 and 60. I am going to try putting some pb blaster or mystery oil in the cylinders and let it soak for awhile before I go any further into the head. which one would you use, pb blaster or mystery oil?
Having said all that a lot of testers will vary with their results. Try it on something else like your car to see if it is just a low reading tester unless you have got better results with the same tester previously.
