Has Anyone Replaced Motor Mounts?

[Happy Place]

What does a collapsed/ failed motor mount look like? I am feeling some increased vibration throughout the boat at a few different RPM settings. I've inspected all 4 mounts and I see no cracking or visible damage of any kind to the rubber. The starboard side aft mount was missing it's locking nut and the main adjustment nut was loose. I've re-tightened it and ordered a new locking nut.....I'm hoping that's the reason for my vibration but even with it tightened, I get dripping from the shaft seal when the engine is running and it's in neutral.

I would be interested in hearing from anyone who has replaced their mounts.

 

[bruceshilah]

I don't know your boat model and maybe it doesn't matter. I have a 2007 R25 classic w/110 hp turbo yanmar. I believe best practice is changing mounts every 4-6 years. Unfortunately my experience has me thinking many owners prefer to maintain some things when the engine flops in the engine bay. I had a drip less shaft seal that couldn't stop leaking under higher rpms and a cutlass bearing wore out. Nobody could figure it out. I pulled my engine out of the boat to sand blast it from salt water being sprayed everywhere and 3 motor mounts dropped off by gravity and the 4th came off with 2 fingers. I bought oceanic stainless steel mounts from Florida that resist diesel fuel degradation. You will need to use lock tight or high strength lock tight to keep the nuts from loosening after fine tune adjustments within 0.08" of the shaft. It's an easy job, but can be tedious to get it perfect. All my problems of leaky dripless shaft seal immediately fixed for the next 300 hours and counting. The engine vibration greatly improved. I'm guessing if you don't know when the motor mounts were last changed assume they're original. The domino effect of wear and tear from not changing motor mounts can get expensive and time consuming. The OEM motor mounts I would not consider due to the mount being under the fuel filter/pump/lines. If your motor mounts look bad they are probably long gone long ago. I hope this helps. You can check out my YouTube videos if you want to see my motor mounts install overview at Inland and coastal boat life.

 

[sgeary]

Since one of the main adjustment nuts was loose, I recommend having your alignment checked before you contemplate motor mount replacement. The vibration you are describing can be caused by poor alignment. But, find a service tech who REALLY understands alignments. It is a bit of an art as well as a science. I once had a "certified Volvo tech" tell me my alignment was fine by simply looking at it, which told me he did not understand alignment at all. When I fired that guy and found a tech who really understands alignments, it turned out to be .045 off and the drive shaft shifted visibly when he remove the last bolt between the prop shaft and the engine. Also, a good alignment will reduce the frequency of tightening your packing gland for the correct drip rate.

 

[OverTime]

Since one of the main adjustment nuts was loose, I recommend having your alignment checked before you contemplate motor mount replacement. The vibration you are describing can be caused by poor alignment. But, find a service tech who REALLY understands alignments. It is a bit of an art as well as a science. I once had a "certified Volvo tech" tell me my alignment was fine by simply looking at it, which told me he did not understand alignment at all. When I fired that guy and found a tech who really understands alignments, it turned out to be .045 off and the drive shaft shifted visibly when he remove the last bolt between the prop shaft and the engine. Also, a good alignment will reduce the frequency of tightening your packing gland for the correct drip rate.

Not a bad idea and surprisingly easy if you have a decent surface gage and some feeler gages. Rotating the shaft is the toughest part. OTH, re-alignment, if necessary, is another matter.

 

[Happy Place]

I need to drive the boat about 1 hour to get to a marina. Am I okay doing this at low speed? If it might do damage, I could get SeaTow to move me....your thoughts?

BTW, I've been consulting Gemini AI on this and it tells me I could destroy the transmission bearings if I drive the boat to the marina...

 

[bruceshilah]

My boat had unknown hours but definitely a number of hours of use in terrible condition and neglect. I'm sure playing it safe is the best, but I'm doing over 300 hours after repairs with no transmission issues and hoping for another 1,000-3,000+ hours in the next few years. I would take it easy though for sure. It's ultimately up to you of course. I'm a gambling man I guess. My boat had a failed engine and transmission report during the purchase and it is doing very good so far.

 

[Happy Place]

I've just come from the boat and I think I've identified the source of the problem. The locking nut on the aft, starboard size mount was loose...I found that a few days ago. The 2" hex nut that raises and lowers the motor has worked it's way all the way down. The aft port side mount is raised up roughly 3/4" higher.

I'm going to count threads on the port side mount and adjust the starboard side adjusting nut to match it, then lock it down. It won't be perfect but it should get me safely to the marina where I can have it professionally aligned.