Engine To Shaft Alignment Question for a 28.5

[Tom]

My 1987 Hunter 28.5 seems to need a better engine alignment. The prop shaft shakes and vibrates to much and allows sea water to enter to fast through the stuffing box.The shaft was replaced about a year ago with a stainless steel type. Any ideas on how to perform an alignment? The coupling is not a flex type.

 

[Ed Allen]

with care

it really is not to bad to do if you can get to all the bolts. remove the cupling bolts.slide the shaft aft untill the cupling faces are clear of each other. as carefully as you can try to center the shaft by moving it side to side and top to bottom. remember the shaft is a bit heavy and will want to lay in the bottom of the tube that runs thur the hull. when you find the middle put a small block or shim under the shaft to hold it as close to center as possible. a notch in a block of 2x4 works ok. then slowly move the shaft back together. the engine side must slide into the other piece of the coupling perfecly straight. when the faces come together use a feeler gage to measre the clearance top and bottom and on the port and starboard side of the cupling face. All sides should have about 5 thousands clearance. if one side is tight the opposite is probably loose. you you then have to move the engine to line up with this spot. if you bump or move the shaft. start over. when you get it so it is perfect on all four sides rotate the shaft and check it again. Repeat untill both faces are perfectly square to each other. You may have to raise or lower the engine or move it from side to side to get it in the right spot. then snug the bolts and check it again.The better you get it the less vibration and wear you will have. Takes a lot of patients to do it. but rewards are ususlly worth it.hope this helps.

 

[S. Sauer]

Engine Mounts

Remember to have two large crescent wrenches to loosen the engine mount bolts and in effect 'move' the front or back of the engine as you tighten or loosen the bolts and then rotate the engine side flange and check with the feeler guage between the flanges. I believe the www.yanmarhelp.com site may have a detailed write-up of the proceedure. Also check the attachment of the engine mount bases themselves where they are screwed into the boat stringers to make sure they are not stripped out or loose from the vibration.