60 PSI preliminary compression test. AQ120b

[MassillonBuckeye]

Hoping the gauge is broke or it wasn't sealed properly.. Going to try a different kit this afternoon weather permitting. Seems awfully low compared to everything I've seen trying to search for low compression issues here.. I freaked out after the first cylinder I tried so I didn't test the others. Partly because of the low reading, partly because I then couldn't remove the test device from the plug hole.. I ended up getting it out, but I don't think I like the design on that kit. I cannot torque the test past finger tight(twisting the hose). Has O-rings on it, so it may be sealing? http://www.autozone.com/autozone/accessories/OEM-Compression-Tester-Gauge-Set?itemIdentifier=424906
That is the kit.
I don't think I did the test quite right and not sure how that would impact readings. I didn't have the throttle open at all, engine was cold(45 deg F.) and I'm not sure if I had a good seal with the tool. Only cranked the engine about 3 times, on two different occasions and got similar results. Going to try again tonight with some 30w oil if I get low readings. I have some seafoam, so I can decarb, but it doesn't seem worth it on such a low reading. How much could it realistically increase with a decarb? 5-10 PSI?

I bought the boat right after Thanksgiving. We started it without much trouble and it ran in his driveway. Would the motor still run with a compression reading that low?

Any input is greatly appreciated.

 

[Don S]

Re: 60 PSI preliminary compression test. AQ120b

Check all 4 cylinders, not just one, you very well could have one bad cylinder, and the reading from one cylinder is not a reason to suspect a bad gauge.
You just screw the hose in the spark plug hole hand snug, not torqued.
Here is how you do a compression test.

View attachment 97_25.pdf

 

[MassillonBuckeye]

Re: 60 PSI preliminary compression test. AQ120b

Thank you Don. I stumbled across another of your posts with this document as well. I plan on a more thorough test this afternoon. I just had a bad feeling and was hoping for some encouraging words! LIE TO ME DON!! haha You guys are great.

 

[MassillonBuckeye]

Re: 60 PSI preliminary compression test. AQ120b

Well my "second opinion" went a little better than my first. All cylinders appear to be 146-150. Plugs looked decent although one closest to the front of the engine(cyl1?) was a bit blackened. Not necessarily oily, but it had burnt some oil somehow. The other plugs just looked fine, just a little brownish.
a). Concerns/fixes for the dark plug? I plan on doing a decarb/seafoam here as soon as I get the tank base welded(aluminum bracket broke) and put back in place.
Also:
b). There were a few small drops of water on the jacket opposite the electrode on cylinder #2, should I be concerned? I chalked it up to a bit of condensation. Weather has been really rainy here in Ohio with temps ranging from low 30s to 61 here over the past week n a half. Been meaning to post some pictures here, I'll try to do that shortly.
Also have a question about a battery terminals on one of my batteries. Came with the boat so unsure of history. Has charge and cranks. The positive terminal post is melted a bit. Looks like where he had a few things screwed onto the post, something was shorting and eating the top of the terminal right under connections. He had the bilge, blower, a radio and a fish finder wired to the battery posts, individually with circle connectors.
c).What happened, and is the battery still usable?

 

[86 century]

Re: 60 PSI preliminary compression test. AQ120b

Yes you can still use the battery as long as the case is still sound.

The melted terminal is most likely from a bad conection at some point.