Coork Johnson
Seaman Apprentice
- Joined
- Feb 20, 2001
- Messages
- 33
A mechanic (auto) friend has recommended that I do ring job on the cylinder with low compression, I just want this thing to last this season, and save my pennies for a new short block as a winter project. Is this a decent idea? He will do for me for next to nothing, exchange labor for stuff that I am good at (computer upgrade).<br /><br />Tested compression today Cylinder 1-3 140 LBS Cylinder 4 35lbs (dry)<br />Wet cylinder # 4 increased to 70 Lbs. <br /><br />Coork Johnson <br />Captain <br />Member # 780 <br /><br />posted March 24, 2002 12:55 AM <br />--------------------------------------------------------------------------------<br />OMC 3.0 L will not go above 2200 RPM, new plugs, new plug wires, new fuel filter, disconnected fuel line and fuel spurts high (no fuel pressure gage available). With out load engine revs normally.. Fuel is from late last year, but stabilizer was added. <br />--------------------------------------------------------------------------------<br />Posts: 26 | From: Greenville, NC USA | Registered: Feb 2001 | IP: Logged <br /><br />DieselWalt <br />Captain <br />Member # 7303 <br /><br />posted March 24, 2002 07:47 AM <br />--------------------------------------------------------------------------------<br />Do a compression check, and be sure the hull is clean and the boat isnt water logged. If it has points, be sure theyre okay. I assume it once ran fine with the prop that's on there. If all else checks out be sure the exhaust shutter isnt stuck shut. <br />--------------------------------------------------------------------------------<br />Posts: 16 | From: Colorado | Registered: Mar 2002 | IP: Logged <br /><br />Coork Johnson <br />Captain <br />Member # 780 <br /><br />posted March 24, 2002 01:19 PM <br />--------------------------------------------------------------------------------<br />Pulled plugs wires one at a time. Engine ran rough when all except # 4 is pulled. Engine runs the same when plug wire # 4 is on or off. Checked for spark on # 4 and has what appears to be a good spark. I will not have compression tester until Monday. Any Interim ideas? Could timing off cause this? <br />--------------------------------------------------------------------------------<br />Posts: 26 | From: Greenville, NC USA | Registered: Feb 2001 | IP: Logged <br /><br />Franki-ESL10072 <br />Captain <br />Member # 6574 <br /><br />posted March 24, 2002 02:09 PM <br />--------------------------------------------------------------------------------<br />If cyl 4 isn't firing, then it isn't likely to be a timing issue..<br />did you check the actual plug on that cyl?<br />if not, change it for another cyl and try again. see if the problem moves to the other cylinder.. I have seen that happen.<br /><br />Check the compression on that cylinder, pull the plug, and stick your finger in the plug hole while its turning over.. if it has a hole in the piston of something else that would cause total lack of function, there will be practically no compression at all.. if it blows past your finger hard, then its probably got enough to at least fire..<br />pull another plug out and use that to compare between the two for compression..<br /><br />its not terribly accurate, but it will tell you if there is a big difference between the two..<br /><br />rgds<br /><br />Frank<br /><br />--------------------<br />In theory,, practice and theory are the same, but in practice they <br />are different.<br />-- Larry McVoy<br /><br />--------------------------------------------------------------------------------<br />Posts: 198 | From: Perth Australia | Registered: Feb 2002 | IP: Logged <br /><br />Coork Johnson <br />Captain <br />Member # 780 <br /><br />posted March 24, 2002 03:46 PM <br />--------------------------------------------------------------------------------<br />Pulled plugs on #1 and # 4 and placed thumb over hole. I could not keep my thumb over the hole on cylinder in # 1, cylinder # 4, I could keep thumb over hole if I used all of my weight, (and I weigh over 200 lbs. and have been called a gorilla by my wife. BTW she normally posts on this site not me, she is churching today. I check earlier posts and noticed that she did not mention that we installed new manifolds last week. Prior to installing manifolds acceleration was erratic on several occasions (identical to current problem, but would clear up on it own, we thought that it was bad gas and once we burned out all of the winter storage gas problem would go away)). We found crack on bottom of manifold (small water leak) while troubleshooting, and that was why we replaced manifolds. <br />--------------------------------------------------------------------------------<br />Posts: 26 | From: Greenville, NC USA | Registered: Feb 2001 | IP: Logged <br /><br />hu g rections <br />First Mate <br />Member # 7031 <br /><br />posted March 24, 2002 08:08 PM <br />--------------------------------------------------------------------------------<br />did u change points & dist. cap? make sure the points are adj. properly. also replace dist. cap. it may have a hairline crack that u can't see. pull the cap & check condition of distributor. any rust build up on the rotor? moisture? <br />--------------------------------------------------------------------------------<br />Posts: 8 | From: brothel | Registered: Mar 2002 | IP: Logged <br /><br />screenbuzz <br />First Mate <br />Member # 7248 <br /><br />posted March 24, 2002 10:04 PM <br />--------------------------------------------------------------------------------<br />i'm not an expert but had a similar problem once with my boat not wanting to get on plane and rpms ran low .it happened right after having lower unit rebuilt. come to find out chokes were not fully opening at full throttle. thay were only opening up about a 1/4 of the way. adjusted throttle linkages, fixed problem boat then planed, rpms ran 5500/6000. <br />--------------------------------------------------------------------------------<br />Posts: 13 | From: louisiana | Registered: Mar 2002 | IP: Logged <br /><br />Coork Johnson <br />Captain <br />Member # 780 <br /><br />posted March 25, 2002 09:04 AM <br />--------------------------------------------------------------------------------<br />I have found reference to a leak down check in my Clymer manual, but no procedure for it. How do you perform? Also where to attach hose for vacuum gauge check to compare compression test results? <br />--------------------------------------------------------------------------------<br />Posts: 26 | From: Greenville, NC USA | Registered: Feb 2001 | IP: Logged <br />--------------------------------------------------------------------------------<br />Posts: 27 | From: Greenville, NC USA | Registered: Feb 2001 | IP: Logged <br /> <br />djohns19 <br />Captain <br />Member # 5471 <br /><br /> posted March 30, 2002 11:44 AM <br />--------------------------------------------------------------------------------<br />Cooork,<br /><br />OH NO! Not good. The engine has to come apart. I suspect broken ring(s) and/or piston.<br /><br />If it's any consolation, I've seen some good deals on 3.0L (long blocks) on e-bay lately.<br /><br />--------------------<br />"If they don't find you handsome-they should at least find you handy." Red/Green.<br /><br />--------------------------------------------------------------------------------<br />Posts: 894 | From: Arizona | Registered: Dec 2001 | IP: Logged <br /> <br />sony2001 <br />Captain <br />Member # 944 <br /><br /> posted March 30, 2002 05:43 PM <br />--------------------------------------------------------------------------------<br />Doesn't your wet test suggest a burnt valve more than a ring problem? Can you get away with a top overhaul only? <br />--------------------------------------------------------------------------------<br />Posts: 267 | From: Montreal,Quebec,Canada | Registered: Mar 2001 | IP: Logged <br /> <br />schematic <br />Captain <br />Member # 4724 <br /><br /> posted March 30, 2002 05:48 PM <br />--------------------------------------------------------------------------------<br />if a substantial improvement is noted on a wet test, it points to cylinder wall or ring issues. From 35 to 70 is substantial......(not good)<br /><br />--------------------<br />Take this with a grain of salt. Heck, I've never even seen your motor......so I'm only guessing.....