Alignment after engine mount replacement

[smokey73]

I am replacing my Yanmar 4JH2E motor mounts and have a question.

I have taken all the bolts/nuts off for the transmission to shaft flange. It was separated about 1 year ago and the bolts came of easily. There is no apparent rust at the flanges. I have a PSS dripless seal.

I know I need to get a little space between the flange surfaces to allow movement/measuring the clearance. I can't seem to get the flanges to separate and move the shaft back a little. I don't know if it is because there is some kind of 'binding at the flange faces or if the spring force on the PSS diaphragm is holding the shaft forward. Any thoughts?

If anyone has had this problem or just know how to get the space so I can continue?

 

[dLj]

I am replacing my Yanmar 4JH2E motor mounts and have a question.

I have taken all the bolts/nuts off for the transmission to shaft flange. It was separated about 1 year ago and the bolts came of easily. There is no apparent rust at the flanges. I have a PSS dripless seal.

I know I need to get a little space between the flange surfaces to allow movement/measuring the clearance. I can't seem to get the flanges to separate and move the shaft back a little. I don't know if it is because there is some kind of 'binding at the flange faces or if the spring force on the PSS diaphragm is holding the shaft forward. Any thoughts?

If anyone has had this problem or just know how to get the space so I can continue?

Is the boat in the water or on land?

dj

 

[jssailem]

I suspect it is the PSS spring forcing the shaft towards the transmission coupling. If you can release the PSS collar on the shaft. Then slide the shaft back through the collar and PSS. That should open up the space at the coupler. If you are in the water, then releasing the collar will allow water to enter at the collar as the PSS graphite donut will not be compressed against the collar. Be sure your bilge pump is working. A rag wrapped about the PSS may help to stop the water from spraying in your face. Any compression of the PSS to stem the water will force the shaft up against the coupler transmission interface. You might have a diver stuff a plastic bag in the shaft log around the shaft to reduce the water flow. Your pump should be able to keep you afloat.

 

[marcham]

Don't forget to use new set screws if you release the PSS collar...

 

[Jan_H]

I'd try to tap a penknife blade in between the flanges to see if they separate, before you loosen the PSS collar. If they do, you could insert a 20 thou ring shim at one of the bolt hole locations, and use that as your reference to measure the space between the flanges.
Jan

 

[smokey73]

The boat is in the water. As @jssailem noted, I suspected it was the compression of the PSS diaphragm that was pushing the shaft forward. Since everything I read says the final alignment should be done with the boat in the water, I can't be the only person who is faced with this? Hoping someone who has done this alignment waterborne with a PSS shaft seal can chime in with the technique.

 

[smokey73]

Another interesting question.
With a PSS there is no restraining action like there is when you have a standard packing gland. The underlying assumption in aligning the transmission output flange to the shaft flange is that the shaft is already "in line" by being restrained by the shaft packing gland and the shaft cutlass bearing. In the case of a PSS, there is no restraining in the radial direction so the only thing holding the shaft in alignment is the cutlass bearing and that is not very long. I can imagine the shaft could be slightly out of line and pressing on the cutlass bearing.

Everything seemed to be in line before I started this so I made a "jig" out of wood that would position the shaft both vertically and horizontally as a starting point for when the shaft is aligned since I did not have any unusual vibration or noise at any rpm before I started this project.

Still, surely somebody with a PSS has aligned their engine and shaft while in the water. How do I assure the shaft is in alignment before I align the output flange to the shaft flange or is it wise to assume the shaft is aligned based only on the restraint provided by the shaft cutlass bearing?