Replacing Engine Mounts: Take One


Click image for a larger view

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.


Click image for a larger view

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.


Click image for a larger view

Click image for a larger view

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.


Click image for a larger view

Click image for a larger view

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.


Click image for a larger view

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.


Click image for a larger view

Click image for a larger view

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.


Click image for a larger view

Click image for a larger view

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.


Click image for a larger view

Click image for a larger view


Click image for a larger view

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.


Click image for a larger view

Click image for a larger view

Below, you can see the newly-installed starboard, front mount.

Click image for a larger view

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.


Click image for a larger view

Click image for a larger view

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.


Click image for a larger view

Click image for a larger view

 


If your comment doesn't show up right away, send us email and we'll dredge it out of the spam filter.


4 comments on “Replacing Engine Mounts: Take One
  1. Rod Sumner says:

    Jsmes:

    If I understand this narrative correctly you had the foresight to take photos of the engine mounts when you took delivery of Dirona – is this correct?

    • Hey Rod. I wish I could claim it was foresight to have taken pictures of the engine leaving the distributor and then again when it came back from the yard in the boat to document engine mount (or other) changes but the truth is it was a combination of 1) me taking a picture of everything that I find interesting which happened to include the engine leaving the Cascade Engine, and 2) Jennifer being creative enough to start comparing pictures from different times to see why the mounts started off thick and seemed to “get thin” early on. We got lucky in having pictures, jennifer noticing it, and the general manager of Poly Flex being customer focused enough to answer questions from a customer in the US and help figure out what happened.

      Unfortunately, on this task, I took a half day job and skillfully converted it to a couple of days of work :-).

Leave a Reply

Your email address will not be published. Required fields are marked *