Compression Problem
Printed From: CorrectCraftFan.com
Category: Repairs and Maintenance
Forum Name: Engine Repair
Forum Discription: Engine problems and solutions
URL: http://www.CorrectCraftFan.com/forum/forum_posts.asp?TID=31425
Printed Date: October-08-2024 at 7:19pm
Topic: Compression Problem
Posted By: Little Lucky Boy
Subject: Compression Problem
Date Posted: September-03-2013 at 2:43pm
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I am the proud second owner of an all original, complete, 1963 American Skier. Starts and runs at idle and low speed but no power. Dry compression is between 135 and 155 lbs. except one cylinder which is 60 lbs. With about an ounce of oil sprayed into the cylinders, the compression is ~155 in all but bad one which goes up only to 80 lbs. Two questions: 1. Does this sound like it could be primarily a valve issue either due to very poor adjustment (are they adjustable) or rings or both? The only thing that was ever done to the engine was a valve job by original owner some time (?) ago. 2. Does anyone have a shop that they could recommend in the central Mass area (Lunenburg is where I live)? Thank you Carl |
Replies:
Posted By: phatsat67
Date Posted: September-03-2013 at 2:50pm
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Sounds like a valve because the pressure didn't change that much with oil in that cylinder. If you are feeling really froggy take the exhaust manifold and carb off the boat. Get an insert that lets you put compressed air in said cylinder. Listen for leaks in the intake or the exhaust port of the cylinder. Easy way to isolate valve problems. When I assembly a new engine generally most machine shops won't lap valves. They will leak until they have been opened and closed a few times. For fast start up I use this method and smack the valves with a soft rubber hammer a few times until they seat and stop leaking. This makes the first start up instant with no fan fair of backfires and such. ------------- |
Posted By: Little Lucky Boy
Date Posted: September-03-2013 at 3:30pm
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Thank you for your quick response oh Grand Poobah. Out of curiousity, why can't I run that test without any disassembly? Wouldn't I still hear it at exhaust pipe and or carb? In either case, how do I make do I make sure that both valves are supposed to be closed at that time? Is there any hope it is a valve adjustment, after all, I am a very Lucky Boy:-) Carl |
Posted By: phatsat67
Date Posted: September-03-2013 at 4:16pm
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Ha there are a lot larger Poobahs here than me! The easiest way to check if the valves are closed on any other cylinder than the number one is to remove the valve cover and check if both of the rockers are up. ------------- |
Posted By: Gary S
Date Posted: September-03-2013 at 4:41pm
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Welcome Carl. Great little fun boats,is yours a Grey Marine 4 cylinder? I had the use of a 64 for 2 summers.I don't know how handy you are or if you have an air compressor but a leakdown tester would tell you alot and http://www.motorcycleproject.com/motorcycle/text/Leakdown.html" rel="nofollow - here are the plans to make one if you felt so inclined. Zach is on the money with the oil and compression,it must be the valves. When it comes to larger poobahs,Quinner says size doesn't matter  ------------- http://www.correctcraftfan.com/diaries/details.asp?ID=1711&sort=&pagenum=1&yrstart=1966&yrend=1970" rel="nofollow - 69 Mustang HM SS 95 Nautique Super Sport |
Posted By: Little Lucky Boy
Date Posted: September-03-2013 at 10:40pm
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Thanks both. Taking off the valve cover an looking at the valve position is great idea. The engine is a V6 with Universal Saber on air cleaner. Don't know anything more about it. Does anyone? |
Posted By: dochockey
Date Posted: September-04-2013 at 9:06am
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Welcome Carl we need to see some pictures of that boat ! ------------- 1989 Teal Ski Nautique 1967 Mustang Harris Float Sunfish |
Posted By: JoeinNY
Date Posted: September-04-2013 at 10:00am
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its a buick engine, if its the sabre then its a 198 cu in 130 hp engine, if its the super saber that bumps you up to 225 cu in and 155 hp. Good running engines.. talked about on this forum a few times. If you have specific questions start asking.. if you want general info I recommend the google... ------------- http://www.correctcraftfan.com/diaries/details.asp?ID=1477 - 1983 Ski Nautique 2001 1967 Mustang 302 "Decoy" http://www.youtube.com/watch?v=cO5MkcBXBBs - Holeshot Video |
Posted By: 8122pbrainard
Date Posted: September-04-2013 at 8:29pm
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Carl, Knowing what engine you have will help. That will tell us if you have solid or hydraulic lifters. ------------- /diaries/details.asp?ID=1622" rel="nofollow - 54 Atom /diaries/details.asp?ID=2179" rel="nofollow - 77 Tique 64 X55 Dunphy Keep it original, Pete < |