Vibration Issue
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=47414
Printed Date: April-28-2024 at 3:07pm
Topic: Vibration Issue
Posted By: bfootr
Subject: Vibration Issue
Date Posted: May-05-2019 at 3:37pm
| Hi- I’ve taken my newly acquired 89 SN on it’s third test drive. Boat has less than 300 hours on the gauge and had been not been driven in 5-6 years when I purchased it. Most of the issues have been corrected (there were MANY) however it still has a somewhat significant vibration mainly between 1500-3000 rpm. It’s got a newly reconditioned propeller and a new ARE shaft. Shaft coupler is within the 3000th of an inch tolerance to the trans flange (checked twice). Both coupler and shaft are fully seated and were lapped fitted. Strut bearing seems fine with no slop. Engine mounts seem to be okay best I can tell. Bolts/brackets supporting engine to stringers seem fine (bolts will bite when loosened and retightened). Engine seems to run smoothly and carb and timing have been adjusted. Not sure if vibration is due to engine, mounts, shaft, propeller, strut bearing or something else. Any thoughts out there on things I should check? Thanks is advance! |
Replies:
Posted By: 8122pbrainard
Date Posted: May-05-2019 at 3:52pm
|
William, Reconditioned props have been know to cause problems. Take it back to the prop shaop and have them check it. Also, did you lap both the coupling and prop onto their tapers on the new shaft? Is the prop seated on the taper and not riding up on the key? ------------- /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 < |
Posted By: bfootr
Date Posted: May-05-2019 at 4:53pm
| Yes, I lapped both coupling and shaft. Also, test fitted prop to shaft without key and marked location with a sharpie to ensure same location once reinstalled with key. Checked key to ensure it wasn’t riding up. Propeller was sent off to “Proper Pitch” for reconditioning and before/after specs were sent back with prop. |
Posted By: 8122pbrainard
Date Posted: May-05-2019 at 5:45pm
|
Besides actually getting the dial indicator out to check the new shaft, the only other thing I can think of is the damper plate. Do you know if it's original? Others may have some ideas so give them some time to respond. ------------- /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 < |
Posted By: MrMcD
Date Posted: May-05-2019 at 7:21pm
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Does it vibrate in neutral? That would narrow down your search. Next I would put on the Dial Indicator Pete mentioned and verify your prop shaft is rotating with no run out at the prop mount.. When on the trailer can you rotate the prop by hand with very little drag? Might need a little soapy water sprayed on the shaft if your strut has a rubber cutlass bearing. Properly aligned you will have little drag. Hope it is something minor. ------------- |
Posted By: bfootr
Date Posted: May-05-2019 at 7:54pm
| Not sure exactly what a damper plate is but it appears most parts are original. Is there a way to check the damper plate? |
Posted By: bfootr
Date Posted: May-05-2019 at 7:57pm
| Does not vibrate in neutral and prop does rotate smoothly with little drag when manually rotated from trailer. It has rubber cutlass bearings. I’ll check the run out on the shaft and post back. Thanks. |
Posted By: SNobsessed
Date Posted: May-05-2019 at 8:05pm
|
Maybe you could check spark plugs, compression, etc. Could be a weak cyl. Also check timing advance. ------------- “Beer is proof that God loves us and wants us to be happy.” Ben Franklin |
Posted By: bfootr
Date Posted: May-05-2019 at 9:33pm
| Spark plugs and wires are new and plugs gapped. I’ll remove all and check compression. Thanks. |
Posted By: 8122pbrainard
Date Posted: May-05-2019 at 9:34pm
Regrettably there isn't an easy way to check the damper plate. The plate is mounted on the flywheel and is basically the connection to the transmission. It's spring loaded to isolate engine vibrations. here's what a typical one looks like:  ------------- /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 < |
bfootr wrote:Posted By: gun-driver
Date Posted: May-05-2019 at 10:57pm
| Sounds to me like you may have crossed a plug wire or as said earlier you have a dead cylinder. |
Posted By: bfootr
Date Posted: May-06-2019 at 12:44am
| I’ve checked and double-checked the wiring. Also, verified that each spark plug was firing. I’ll need to check to see if compression is off in one or more cylinders. Will post back what I find out. Thanks for the suggestions. |
Posted By: bfootr
Date Posted: May-06-2019 at 12:49am
| Checked it again tonight and I will say that there is some drag when rotating the prop by hand. Smooth but some drag - In other words, it won’t spin freely. Not sure what is normal. |
Posted By: 8122pbrainard
Date Posted: May-06-2019 at 8:02am
|
The shaft isn't going to spin freely. Even with the cutlass lubricated, there's still drag from the shaft packing. Is the drag consistent through the 360 degrees? I'm wondering if what you are hearing is just harmonics. All boats will do it at certain RPM's. I would describe it more of a buzz than a vibration. ------------- /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 < |
Posted By: bfootr
Date Posted: May-06-2019 at 8:08am
| Yes, it’s a consistent drag and it’s definitely a vibration as it shakes the ski mirror a good bit. Going to test drive it again today and will update. |
Posted By: 8122pbrainard
Date Posted: May-06-2019 at 10:49am
The mirror vibration is pretty common due to harmonics at certain RPM's. Report back after the drive today. ------------- /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 < |
Posted By: bfootr
Date Posted: May-06-2019 at 6:09pm
| Vibration is still there. Really evident between 700 - 2500 rpm. Seems to go away at higher speeds. Engine seems to be running smooth with no misses. Going to check both compression on every cylinder and run-out on the shaft at the taper. Will post back what I find. |
Posted By: MrMcD
Date Posted: May-06-2019 at 10:01pm
|
Do you have an extra prop you can test with, maybe a friend with a spare you can use. A magnetic mount dial indicator will tell the story on your prop shaft if you test it with the prop off and test very close to the end of the shaft near the prop mount. It is a little hard to find a place that is close but does not have the slot for the key. Since the prop comes off the measure might be a good time to run a test prop. You will get it figured out. It is just parts and one is currently not in good shape. Mark ------------- |
Posted By: bfootr
Date Posted: May-07-2019 at 12:32am
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Thanks. I’ll have to see if I can borrow another prop somewhere. I did check the run-out on the new ARE shaft this evening and it’s good....Less than .002”. Going to check compression in the next day or so to see if a cylinder is dead? She’s running great just the annoying vibration. |
Posted By: bfootr
Date Posted: May-08-2019 at 11:11am
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Checked compression today... Cylinders 1-4 all show 135 psi Cylinders 5,6, and 8 show 130 Cylinder 7 the lowest at 125 Compression seems to be much better than when I first checked it soon after we unseized the engine. Are these numbers within specs? Any concerns with these? Thanks so much.... it’s great to be able to leverage the expertise found on this forum! 
|
Posted By: phatsat67
Date Posted: May-08-2019 at 11:36am
| Numbers sound just fine. |
Posted By: MrMcD
Date Posted: May-08-2019 at 3:42pm
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Compression numbers within 10% of each other is considered normal. ------------- |
Posted By: SNobsessed
Date Posted: May-08-2019 at 7:14pm
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Others will know, but I am wondering if the seized/unsiezed engine has something to do with vibration. ------------- “Beer is proof that God loves us and wants us to be happy.” Ben Franklin |
Posted By: gun-driver
Date Posted: May-08-2019 at 8:15pm
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How hard was it to get free? How did you do it? |
Posted By: bfootr
Date Posted: May-08-2019 at 10:23pm
|
Crankshaft wouldn’t turn manually with a socket/ratchet so I took out all of the spark plugs and squirted a mixture of acetone and ATF in the cylinders and in the intake. Let it soak for a few days and I was finally able to manually turn the crankshaft. It was evident that rust and debris was blocking the pistons (valves too I believe). Boat had not been cranked for several years. Thankfully, it appears that the block and manifolds had been drained. Here’s what I’ve replaced to date to get the engine running: - Starter and Starter Solenoid - Fuel Pump - Change to electronic ignition with new coil (which allowed bypass of resistor) - Carburetor (rebuilt) - Alternator - Impeller - Spark Plugs (Autolite 24 w/.035 gap) and Wires - Changed the oil twice to ensure most the engine crud was gone. Using Mobile One 20w-50 Full Synthetic and Mobile One filter - New Trans Fluid She’s running great now - Just got to figure out why the vibration. |
Posted By: KENO
Date Posted: May-08-2019 at 10:39pm
Whether I'm in a boat or a car/truck that mirror is always one of the best indications of a vibration issue in the drivetrain. So............don't accept it as normal and keep after finding it. You wouldn't be the first guy that had a rebuilt prop that has vibrations associated with it. |
Posted By: bfootr
Date Posted: May-08-2019 at 11:25pm
| Thanks. Im leaning towards the issue being the rebuilt prop as well. Checked and double-checked most everything else! |
Posted By: MrMcD
Date Posted: May-09-2019 at 1:45am
|
It does not vibrate in neutral. That may mean the engine is fine but running the boat in the water puts a lot of load on the engine and may make an issue show up. When the prop shaft was being installed did you get the coupling dialed in so the coupling and prop shaft are mated and with less than .003 clearance at all parts in the rotation. Also rotate the prop shaft while the coupling at the tranny does not turn and make sure the measurements stay the same as you rotate, I would check after a 90, 180, 270 rotation just to make sure the coupling is square to the prop shaft. Isolate your problem to find and repair it. It may still be a bad prop repair, it has happened. Also possible someone dropped your prop after the repair and tweaked your blades. Mark ------------- |
Posted By: bfootr
Date Posted: May-09-2019 at 9:40am
| Thanks Mark - I’ve checked the coupler and trans flange twice just to make sure. I’m going to check it one more time rotating it as you suggested. If it’s within specs, going to assume it’s the prop. Appreciate the suggestions! |