Shaft alignment on buzzards bay

[Ereiss]

I'm getting a high pitched squeak when under way(not at even elevated idle) and I can see some vibration in the shaft when this occurs. Any recommendations on someone in the Marion, ma area to take a look at it and adjust as necessary? Thinks it's beyond my pay grade.

Thanks

[GeoffSchultz]

Ed,

It's probably not beyond your pay grade. Once you've done it once...or many times in my case...it's quite easy.

What you need to do is:

• Get yourself a set of feeler gauges
• Remove the bolts from the transmission flange
• Split the flange so that the two pieces come apart. This may be easier said than done.
• Push them back together leaving a very small gap and make sure that they go back together smoothly and don't bind due to rust/whatever. If there is rust, clean it up.
• Rotate the shaft to see if there's one angle where it binds.
  • If it binds, think of this as a V which is rotating and at one angle the V will be closed and 180 degrees from there it'll be open
  • Determine where it's closed and think about how the engine will need to be moved to equalize the gaps. For example, if it binds on the port side, then the rear of the engine either needs to move towards the port or the forward end of the engine needs to move to starboard. Likewise for up and down. It gets more complex on non-90 degree angles, but you get the picture.
  • If you need to move L or R, loosen the engine mount bolts on both sets of either the front or the back engine mounts which attach it to the stringer and shake the engine to move it sideways.
  • If you need to move up or down, loosen the bolt from the motor mount which goes to the engine flange and then use the adjusting nut to raise or lower the engine.
  • Repeat until it doesn't bind
• Now take your feeler gauge and find the thickest one that will fit into the gap between the flanges
• Move the feeler gauge around to determine where it binds.
• Keep repeating the above adjustment procedure until the gap is within .002 to .005" of being parallel
• Tighten down all of the bolts and take it for a test run

-- Geoff

[Ereiss]

Geoff, thank you so much. A clarification, when you are in the "rotate and bind" stage I assume you have the bolts together(loosely?). Best way to separate the flange pieces? How much space do you create to allow for removing rust between?

Again, thanks.

[GeoffSchultz]

Geoff, thank you so much. A clarification, when you are in the "rotate and bind" stage I assume you have the bolts together(loosely?). Best way to separate the flange pieces? How much space do you create to allow for removing rust between?.

1. The bolts are completely out or they can be in. The engine is out of line with the prop shaft, so its generating the "V". Just rotate both flanges together.
2. Separating the flanges may be the hard part. It was for me. I'd dry a brass mallet (Harbor Freight) to break the two apart and then try to pull them apart. If they don't want to separate, try a screw driver or a chisel to drive them apart. Be careful not to damage the flanges too much as it will make measuring the gap difficult. Your shop may have a sliding hammer to separate them, but getting enough space to do this between the flange and the stuffing box may be difficult.
3. I separate them by inches so that I can get in there and clean them up so that they rotate cleanly. Expect to spend a lot of time on your back in uncomfortable positions.
4. Push them back together so that one surface is touching/almost touching. When you're done, you'll have them within .004-.010" apart most likely with a differential of .002-.005"

-- Geoff

[rds]

Sorry I, do not mean to highjack this thread, just sort of related question.
How hot stuffing box is supposed to be ? Can engine misalignment cause stuffing box to heat ?
I've changed flax packing in my stuffing box. Flax I bought is something like braided cotton threads saturated with graphite based lubricant or something like that , specs says: 266 F deg. max temp. I checked the engine's alignment roughly, shaft strait and did not bind or wobble and rotated freely, not over tighten.. so I launched my boat last Friday. I checked the box shortly after and noticed that stuffing box was really hot, I could not hold my hand on it . I opened it about half turn more ..made 2 hours motoring to another marina like that. What temp is considered to be normal ? how sensitive this thing is ? ( I mean scored shafts stories ) b.t.w. I noticed that clearance between the hole in stuffing box and shaft is really small so in theory if shaft is not straight , scored or wobbles then it can touch the box and cause that sound / heating.

[THATBOATGUY]

To RDS

You should have the packing nut loose enough to allow a slow drip while motoring along. Any tighter than that is too tight.

Also, it's often futile to do engine alignment on the hard. Our boats are plastic and they do bend a bit when out of the water. I recommend not doing alignment until the boat has been floating for a few days. Some folks (including Nigel Calder) recommend going so far as to go with half full tanks to simulate an average loading!

George

[Ereiss]

Well, decided to have the yard do the alignment with me watching and helping (calling it a tuition payment). The shaft was .009 out of line, got it back to .002. Can now rev up to 3k withou any of those squeaks showing up. A very satisfying day. Thank you all for your advice and help. Watching someone do it makes it clear how straight forward a process it is.

[GeoffSchultz]

Glad to hear it. How many hours did it take? Any issues getting the flange apart?

-- Geoff

[Ereiss]

Flange came right apart, guess because work had been done 2-3 years ago. Total time for the alignment was less that 3 hours given then back and forth on the adjustments. He found that the bolts attaching the engine mounts to the stringers were not very tight, which probably was the problem. Also found that I was spitting oil out of a bad bonnet (head cover to you and me) gasket and there is a crack on the tube coming out of the breather tube (part on order). Can't tell you how pleased I am to have the engine (knock on wood) running smoothly without fear of pushing the rpms up to 3k when needed.

Geoff, your directions were perfect, if I had the time and knew how simple it was I could do it, but, as I said, seeing someone do it makes for a small boat tuition payment happily made.