engine mounts bad?

Ralph Johnstone · Mar 12, 2012

A Visual Inspection ..........................

.................. is probably your best test.

If none have had a fuel leak on them (as one of mine did) they should be solid and not need replacement. Replacement cost for one is a bit of a coronary at $278.26 four years ago

.

There's no maintenance schedule on them because if they're kept clean, they probably last forever.

My suggestion would be to visually inspect them in place and if they're solid, they're good to go.

Tom J · Mar 13, 2012

How is your prop shaft to engine alignment? Sometimes the engine mounts settle to the point that it is no longer possible to align the prop shaft coupling. Might be time to think about new engine mounts at that point.

walmsleyc · Mar 13, 2012

You can look for two basic issues when inspecting your mounts:

1) Unusual damage: rubber deteriorated, broken, detached, etc.
2) Normal wear and compression: Depending on you motor and and you mounts, you can measure that remaining space/gap between the top and bottom part of the mount (a diagram would help, but I don't have one!). I "think" that is must be >= 3/16" (for my 75 & 100 mounts for my 3GM30F).

Assuming no outright damage, check the remaining space under each mount. On my 1987 Legend 35, I assume the mounts are original, some of the mounts are at the very end of their lifespan. The rubber has compressed over the years, until 2 of my mount are at the limit. When I bought the boat, I have a feeling that it had not been aligned for years (ever?). I was totally unable to align the shaft because I had raised my mount to their limit on the front two mounts, and the shaft was still not aligned. I had to build shims to place under my front mounts to allow me enough adjustment range to get the shaft properly aligned. Even still, my engine was near the top of the mount bolts (which is undesirable).

I expect that I will replace the mount in the next few years.

Chris

JST123 · Mar 13, 2012

Simple test, gian access to be able to view your mounts. Start your engine and put it in gear to load up the drive train. apply as much power as you safely can assuming you are tied to the dock. Look at the mounts, you should be able to see the mounts moving with the engine look to see if any are moving more excessive than the others. I noticed last week end in a very heavy wind 25-35 kts an excessive vibration. I went back in and found one of my engine to mounts loose. Simple fix, tighten up then went back out and buried the rail!!

Ralph Johnstone · Mar 13, 2012

Jared1048 said:
How long of a fuel leak? What did it look like?

Looks fine to me but I dont know what im really looking for.

cheers
Jared

The fuel leak was very small ................ was coming from the lift pump, following the contours of the block, and settling on the mount. The mount was in a hard to see location so the leak had been going on for approximately three to four years.

What finally got me looking at the mount was another small leak ............. this time from the vacuum breaker mounted on the side of the block and releasing a very fine spray of sea water on to the mount. By the time I looked at it, the rubber was showing signs of becoming a little gummy on the surface.

I'm sure that this wasn't enough time to fully penetrate the rubber mount but it was a start. Also the steel housing was a rusty mess by then. I'm a little OCD about my engine so decided to replace the mount then and there rather than wait for it to completely fail a number of years down the road.

robertsapp · Mar 14, 2012

I think engine mounts are one of those items where we all follow the philosophy of "if it ain't broke, don't fix it." I've researched them in the past, and I've found various mentions of Yanmar directing that they be replaced every three, five, or ten years depending on where I looked. Our boat is just over sixteen years old, and I replaced all four mounts last month to the tune of almost $600. It made a major difference in the ability to align the engine. As in, before, it was impossible. Now, it lines right up. So I consider it money well spent.