Re: 2000 5.7 GS Low Compression
I agree with Jerry, why bother with a leak down? He already squirted oil in the cylinder, it made no difference. It has 90 psi at cranking speed which shows some compression so if he did a running compression test I bet it would come up to 120 or so. If it had a hole in the piston that would be obvious. Since all the other cylinders seem okay we can assume for the time being that the valves are probably okay. That leaves rings which fits.
Mr. 300sflyer doesn't describe any driveability complaints although I assume that is why he did a compression test in the first place. He also doesn't say if there is any smoke or what the spark plug looked like on that cylinder. Now the only reason I like to have that information is that sometimes we can make a diagnosis right through these little screens we all are staring at. With a fouled plug and white-blue smoke its rings and it's time for that motor to come to Jesus. I like Jesus he's a pretty good nut buster who worked for me years ago. Yes, I am that old. No seriously, I know it makes guys feel like they're doing something to pull heads since it's not all that difficult and for some guys (me included) it's kinda fun. If you want to pull the head, by all means yank that puppy and send pics. Then arrange for the engine (s) to be pulled and replaced with a couple of sweet strokers. Getcher self a couple sets of props the next pitch up and then skip the next two boating seasons because you can't afford gas for your kid's Geo let alone the boat since you just blew 10K on motors and props. Seriously though I kid. Yes, I seriously kid you. Hey thats original, "I am seriously kidding" Wow I should write for Leno or Letterman. Anyway if one engine is showing a bad cylinder keep in mind both of them have the same amount of hours and perhaps it be engine replacement time. If it were my boat, and boy I kinda wish it were that's a real sweet cruiser, I would definitely start looking into twin strokers. I don't think that will allow you to move up in pitch but the extra torque and hp should be noticeable. Strokers don't cost all that much more than stock 350's but you'll have to find a builder that knows what they're doing.
Well I'm busy spending your money here so it's all easier said than done, but do let us know what ya find. FYI I had a bad ring in the #5 hole in my 350 for a couple of years, it dropped from 140 to 75 cranking compression over the seasons and was puffing smoke a bit. It actually ran pretty good and I pulled skiiers and toys around plenty like that. I noticed the power loss, and you probably do to because of the difference in throttle settings between the two engines. I really think you'll be pulling a motor so may as well get started if you want to use the boat next season. I hope you show I'm wrong and I'm wrong a lot such as thinking I'd bounce back from three torn rotator cuffs and be back cage fighting by now but noooooooo "You're an old man now!" they all say heck with them I can kick butt with one arm tied behind my back or in a sling anyway since I'm still building motors with one arm. Of course that's just the pain meds talkin and I've just wasted 6 minutes of ya'lls time you'll never get back.
