In Boston we noticed that our forward engine mounts were starting to deteriorate. We purchased replacements but expected the current ones to last for months yet.
While in Newfoundland, they suddenly started deteriorating badly and over two weeks the isolation material just crumbled away in a pile around the mount. One morning we picked up a fair bit of vibration in the drive line. Measuring the rear-mounts, we could see that the engine had settled 0.250″ as the front mounts had crumbled away.
We knew we needed to change the mounts fairly urgently and realign the drive line, but we aim to never to have to stop for mechanical issues and to be able to fix these things when we have spare time. However, the vibration that showed up this day was bad enough that something needed to be done to avoid other problems. Having noticed that the front mounts had settled a 0.250″ when measured against the rear mounts, we did a quick-and-dirty adjustment and just raised the front mounts by that 0.250″. An engine alignment involved adjustments to an accuracy of a couple of thousandths of an inch. Amazingly, this temporary procedure worked so well the vibration was nearly eliminated.
Over the course of the subsequent week, the mounts continued to crumble and as we arrived into Bras d’Or Lakes from Newfoundland the vibration was again setting in. We decided to replace the isolation material in all the engine mounts since we had the parts on hand from Boston.
We carry a five-ton hydraulic jack on board, but space under the engine is tight and we couldn’t find a location to place the jack in order to lift the entire front of the engine. We instead placed the jack first at one forward corner to replace that mount insert, then at the other forward corner to replace it.
In the two pictures below, James has jacked up the starboard, forward engine corner and is removing the bolts securing the mounting pad to the hull.
With the engine corner raised, we were able to tip and slide the engine mount out from the engine support bracket. In the second picture below you can see that only a small portion of the yellow bottom insert remains.
All that remained of the top mount insert was a thin ring. The third picture below compares the remains on the left to a new piece on the right.
In the two pictures below, James is fitting the new top and bottom mount core inserts to the mount base before re-installing the base.
Below, you can see the newly-installed starboard, front mount.
We then transferred the jack over to the port side and repeated the process. The mount cores on this side were in just as rough shape as the starboard ones. Each mount filled a dustbin with debris. The yellow dust from the bottom core piece was sticky and ground into the non skid, so we had to scrub the engine room floors after the job was complete.
We ran into two problems on this job. The first was that it was not possible to lift the engine up enough to remove the rear mounts without completely removing the prop shaft and potentially the exhaust. The second problem is the mount isolation material we’re installing appear to be thicker then what was previously on the boat. On the left below is what the port front mount looked like leaving Cascade Engine (the Pacific Northwest Region John Deere distributor) and on the right is how it looked when delivered from the yard. The final install in the picture above looks like the original mounts at Cascade rather than what was ultimately delivered.
So we want to check-in with the mount manufacturer to ensure we have the right parts and to come up with a way to more easily replace the rear mounts. We did just a quick-and-dirty alignment as it actually works fairly well, and a full alignment would take us a few hours. Since we’re only halfway done, we won’t bother to do the full alignment until we can complete the rest of the job.
See Replacing Engine Mounts: Take Two for the second part of this job.