1978 hunter 30 ysb 12

[H-30 newbie]

Ok so i bought a h-30 got the ysb 12 running but it has a ridiculous amount of vibration under way makes me think the clearance is off it shouldnt be this rough can anyone tell me what the clearance with the feeler gauge is and I've read you make adjustments to the motor mount to adjust clearance?
I'm diving into this today and would really like to do this by the technical specs.i can take pics or whatever any help would be greatly appreciated.

 

[cagreen75]

First you must be aware that if you have a mechanical seal (mostly known as a PSS seal) be aware the if you do this with the boat in the water the seal may leak prompting an immediate haul out to keep your boat from sinking. I don’t know about your boat but I think most have a coupler on the transmission shaft that attaches to the propeller shaft via a second coupler. If you loosen the bolts in the coupler and the bolt that locks the coupler to the propeller shaft you should be able to slide the propeller shaft coupler back just enough to get a feeler gauge between the coupler faces. The bolt that locks the coupler on the propeller shaft should be re-tighten. You would then find a feeler gauge that fits at the 12 o’clock position. It does not matter what size the feeler gauge is. Without turning the shaft check the clearance at 12 o’clock and 6 o’clock. The clearance should be the same. Repeat that procedure at 3 o’clock and 9 o’clock. If any of those clearances are different the engine is out of alignment.
I would suggest that if you find differences in the clearances that you hire an experienced marine mechanic to adjust the alignment as it is very complicated and difficult to get the engine properly aligned. This is due to the four engine mounting points. The engine must be set so that when you tighten each bolt the feeler gauge clearances do not change. If that happens your engine mounts can be either compressed or pulled apart. Another thing to look at would be buildup on the prop or worn zincs that may be causing an out of balance issue. The cutlass bearing should also be checked for wear. If all those things check out ok then you may need to check the engine compression. Uneven compression can under load cause the engine itself to vibrate.

 

[H-30 newbie]

Thank you i found the coupler shaft but it was the rear mounts were almost off tightened them and she's so much smoother now.

 

[cagreen75]

That good news. You are indeed lucky to find a simple solution as the other things that can cause vibration can sometimes be difficult to track down. Happy sailing!