Engine vibration

[gabosifat]

Hi All,

Just wondering if anyone has any ideas on the engine vibration we're getting. I've noticed it a bit more over the past few months. It cycles on and off on with a regular rhythm. It lasts maybe 3 seconds, goes away for 3 seconds and then comes back for another 3. I do notice it happens more when the boat rolls from side to side. I just pulled the boat, did the bottom & replaced the zincs thinking the zincs might have corroded in a way that would throw the shaft off balance. The cutlass bearing was tight with no play & the shaft spins easily by hand with the engine in neutral. I haven't checked the the engine alignment or the motor mounts yet - that's my next task.

The boat is an E35/3 with a Universal M35A 30hp with a 15 inch three blade Maxprop. The boat cruises easily 6.4 knots at 2200 to 2300 RPM.

Would appreciate any suggestions.

Thanks to all who respond,

Steve Gabbott
E35/3 "Silent Dancer"
Vancouver

 

[Sean Engle]

I would start by going over the side and checking the zincs to ensure that they've not become loose somehow...

//sse

 

[gabosifat]

Hi Sean,

Good advice, but I only just plunked the boat in the water yesterday with new zincs (hammered and tightened properly).

Thanks
Steve

 

[escapade]

Shake/rattle & vibes

Definitely check alignment and that the motormounts are tight. If it seems to get worse as the boat heels would indicate that the motor is shifting (loose motor mounts) and/or misaligned. Remove the four (4) bolts that hold the flange to the trans and slip a strip of Sears (Victoria's Secret, whatever!) catalog paper between each ear and the flange. Push the shaft back up snug and pull on each piece of paper. They should all have the same amount of "drag" as you pull them out. Also, the shaft should line up perfectly with the engine. In other words you should just slide it against trans flange without having to push/pull it around to get it to engage. The motor mounts are adjustable both up & down and side to side. The bolts should be tightin the hull as well as on the motor. Adjust the motor until you satisfy all the above conditions. Will probably take an hour or more and lots of "engineering fluid". It's a good ides to put epoxy on the threads of the lag bolts that hold the mounts to the hull. It allows them to hold much better and seals the stringer from moisture.
If this doesn't help then you must check that the prop is tight on the shaft and balanced and/or replace the motor mounts($40.00 ea. from Marinedieseldirect.com). Checking the prop means a haulout.
Hope this helps.
Have fun & sail fast
Bud E34 "Escapade"

 

[ted_reshetiloff]

Bud I love the Victoria's Secret catalog idea! Dont want to think what the admiral will say when she finds pieces in the bilge though...

 

[pick]

I'm having some problems with the lag bolts holding the engine mounts becoming loose. Putting epoxy on the treads seems like a good idea, but what if I want to adust them in the future is it possible to loosen them?

Mike Pick
E32-3

 

[Loren Beach]

thread "trick"

Put some wax on the threads of any fastening that you want to later remove from being bedded into wet epoxy...

Loren

 

[newgringo]

Our 1986 E32-3 with a M25 Universal does the same thin when the boat is rolling. I "suspect" the engine is moving in the mounts from side to side causing shaft misalignent stress but sure do not know. Will be very interested on what you find.

 

[Glyn Judson]

Engine noise, bad motor mount.

Jerry, Jean, Steve and all, I too had that problem way back when I'd just gotten the boat and didn't knbow any better than to check the mounts. Mine also only vibrated noisily when the boat dipped to port when under power. Sure enough the aft, port mount on my Yanmar 3GMF engine was bad. I replaced that one mount and left the others alone. Almost 12 years later the engine is still snug and tight. Glyn Judson, E31 hull #55, Marina del Rey CA

 

[newgringo]

Glyn - Really good info to know. I think I'll put new engine mounts on my list to do when I pull the transmission etc this winter. Probably 20 years old. Winter coming soon enuf too!