Replacing motor mounts, rotting stringer?

[mattman]

Hi folks,

I've been planning to replace my motor mounts due to excessive wear and vibration as of late. As expected I've hit all sorts of roadblocks along the way.

Engine: 1984 Westerbeke W21
Mounts: Bushings 1x DF-100 in front, 2x DF-22205-2 in rear
Photos: https://photos.app.goo.gl/K4NS3LnM21TYA84Q9

Problem 1: Supporting the engine

I'm a bit stuck on the best technique for supporting the engine. I don't own a bottle jack, but I have a scissor jack. I can place a wood block over the jack and try to support it via the oil pan, but the angle of the "bilge" that the jack will be supported by, and the weakness of the oil pan has me worried about this.

Another approach would be a basketball, inflated just enough so that I can loosen the bottom nuts.

I honestly can't find a great place to jack the engine up which is why I've been hung up here.

(Lifting from the top is not an option, the engine bay is completely enclosed.)

Problem 2: unable to get a socket around the port nut


So far I've been able to get 2 mounts loose, but I'm stuck on the 3rd. The engine seems to have rotated over the years and the now port side top nut is so close to the wall of the engine bracket that I cannot get a socket around it (photo here https://photos.app.goo.gl/KigMuCKufAzn1B3u6)

Once the engine is supported via Problem 1, and I've disconnected the transmission coupling, since I have new mounts I see two options:

Option 1: cut the bolt below the engine bracket and attempt to pry the top half of the bolt up and out through the engine bracket. Then I can unbolt the mount from the stringer and slide it out.

Option 2: loosen the bottom nut along with the other mounts and try to pry the engine into rotating just enough that I can get a socket around the top nut.

Any concerns with either approach?

Problem 3: How concerned should I be about the stringer condition?


Now, if you've seen the photos (here is a good one https://photos.app.goo.gl/qPYALRW4AWT1kZLj8) you'll see a crack along the stringer and the metal u-shaped support around it in pretty bad shape. Next time I'm at the boat I'll feel around the crack with a knife and try to assess if the wood is rotten, etc. But I only recently noticed this, and I'm a little unsure how alarmed I should be. I suppose it's possible that someone added that metal bracket around the stringer to prevent that crack from getting worse?

Problem 4: Putting the new mounts on

Assuming the I'm able to support the engine, get the old mounts off, and the stringer is fine, I'll want to do everything I can to make the new mounts as solid as possible.

Nyloc nuts: I plan to purchase Nyloc nuts (5/8"-18). Do folks who went nyloc on their mounts typically do nyloc above AND below the engine bracket?

Washers: Should I add washers above/below the engine bracket? Presumably 5/8" ID, and the biggest OD that will fit within the bracket? What thickness is ideal, or is this overkill?

Anti-seize: I've got anti-seize compound that I used for my glow plugs. Should I use that on the threads before reinstalling?

CRC Corrosion inhibitor: Can/should I use CRC on the new mounts once installed? Bushings says it's a synthetic rubber that resists oils, etc, but I'm worried about getting it on the rubber. Is there a better spray for this?

Alignment: I plan on doing rough alignment with the new mounts and waiting 2 days before doing fine alignment. Any other tips here?

As always many thanks in advance for any support here!

[model 10]

I cut the box end off a 15/16"wrench for a couple of nuts on my engine.
Pull the engine, those stringers look like ****. Lots of boats have engine installations that bad so don't feel too bad.