Changing Engine Mounts - Difficult? - Expensive?

[Dave]

Hello All

Took the family out for a cruise yesterday. It was a beautiful day. The water was smooth (for a change). So for the first time since picking up the boat in November, I ran her at WOT.

She ran at 4900 rpm and averaged 41 mph (via GPS) on two reciprocal runs. The engine was very smooth and sounded great. Temp and oil pressure looked perfect. I am extremely happy with the performance.

Upon returning to the pier and checking the engine compartment, I discovered rust flakes laying around the two forward engine mounts. From previous inspection, I knew the mounts were corroded, but I believed them to be solid with plenty of life left in them. Now after seeing little piles of rust around each mount following the vibration/torque of a full throttle run, I am not so sure. I can only imagine a broken engine mount while underway would lead to very expensive damage.

So the questions on my mind this morning are:


How difficult and expensive is it to change the forward engine mounts?

How ugly can the mounts be and still reliably secure the engine in place?

Is there any way to test the mounts to re-assure myself they are doing there job?


Thanks for any info or past experiences that anyone can pass on.

Mercruiser 5.0 MPI w/Alpha One

[seapuppy]

that's really hard to say when to replace the mount...what you may have is slight surface rust...cleaning it off and repainting might just end the rust flakes......
.it isn't hard to replace if you have the tools..something to lift the engine off it's mount.(note ..don't use a jack..they tend to push thru the fiberglass.)..so a hoist would be recommended....then just 4 bolts holding it to the engine and a couple holding it to the transom....hope this helps.....

[Dave]

The corrosion on the mounts isn't pretty. I have had them on the list of things to be changed since picking the boat up. I kind of had them in the back of my mind for next spring (spring of '09) or something. But now I am thinking it may be better to change them sooner rather than later. If for nothing else than peace of mind.

Doesn't the outdrive have to be removed before lifting the engine at all? Or does the coupler flex? Isn't a realignment, with the outdrive removed, in order after putting new engine mounts in?

While I am deciding what to do, I'll go ahead and take a wire brush to them and get all the loose scale cleaned off. Maybe they aren't as bad as I think they might be and I'll be able to save whats left of them.

Thanks for the help

[seapuppy]

the best way would be to remove the drive and lift the engine...then replace the mounts...yes..after you replace everything..an engine alignment should be done to make sure you don't have any flexing with the drive shaft ..u-joints and coupler...those couplers aren't cheap...so...be careful with those...after it's aligned..reinstall the drive...should be ok then..but I agree about the wire brush....that will tell you how badly the mounts are rusted....it may just be surface rust and chipping paint...let us know how it goes...

[Dave]

The mechanic checked the engine mounts while doing the annual service. He said they are fine for now. He cleaned them up and coated them with lubricant/corrosion block to try and slow down the rust.

I feel better to know they still have some life in them.