Hunter 326 - Yanmar Engine Vibration - New mounts and maybe more??

[Breezy1]

Just purchased a 2003 Hunter 326 and I noticed at about 1800 RPM there is alot of banging and vibrating. Upon further investigation I uncoupled the prop shaft from the transmission and it is significantly out of alignment. So - it has been recommended that I replace the motor mounts and while I'm at it i should replace the stuffing box log, the cutlass bearing and possibly the shaft!! Yikes!

I'm all about doing things right but I don't care to waste money and time on un-necessary items.
Seeing if anyone has any recommendations - starting with the mounts - OEM or aftermarket and how do I know they are bad!
Thanks!

 

[Slipin Away]

start with cutlass bearing first. Worn out bearing will cause misalignment

 

[Ralph Johnstone]

So - it has been recommended that I replace the motor mounts and while I'm at it i should replace the stuffing box log, the cutlass bearing and possibly the shaft!! Yikes!

My first suggestion would be to stay away from the source of information which recommended all of these expensive repairs. My next suggestion would be to approach your problem in a constructive manner.

The vibration in your engine may well be due to the misalignment but the best way to test that is to correct what you say is a bad alignment.

First step is what caused the misalignment ? The motor moves the most. The shaft not so much so ignore that for now. While you are disconnected, does the shaft move vertically or horizontally ? What do your motor mounts look like ? Is it close to these clearances ?

Does your engine move around easily with the shaft disconnected ?

Upon further investigation I uncoupled the prop shaft from the transmission and it is significantly out of alignment.

Significantly doesn't cut it. What is the exact angular misalignment in 0.00X", any vertical or horizontal misalignment . What is the flange dia. of the shaft and xmission ?

Answer those questions and it means you're interested in solving your problem as opposed 50% of all enquiries we see here from people who want us to come over and fix their problem but don't disturb them in the process. We'll look further next time.

 

[Benny17441]

What is the engine, a 2GM-20F? Do not start replacing parts wholesale. I would have the prop cleaned and balanced. check the valves lash in the engine. Inspect the motor mounts for breakage and softness. ( to test mounts lift the engine up at the mounts with a pry bar, if the mount is broken it will separate and lift clear. If it is soft it will stretch and elongate.) Align the engine and shaft until the shaft is turning in a concentric fashion with minimum wobble. At this point you have not spent in new parts and you may determine whether there is adequate improvement or not. For a 20 year old boat a certain degree of vibration in the drive train is anticipated. If you are not satisfied and decide to replace parts, do the motor mounts first and realign, follow with the cutlass bearing , and leave the shaft replacement for last as a last resort.

 

[sail sfbay]

Also inspect the propeller............a damaged propeller can cause vibration due to vortex sheding........I know because I observed this on my new to me on my Hunter 46 during the sea trial and once I hauled the boat confirmed propeller had holes due to corrosion.

 

[Breezy1]

start with cutlass bearing first. Worn out bearing will cause misalignment

Good thought. It's really cold here in Michigan and I've got to get down to the marina and check all these things out, which is exactly why I figured I'd ask before I go wild making changes etc......

 

[Breezy1]

Ralph - Yes thank you for your advice. I do have to do more investigation and measurements. I'm a mechanical engineer, but experience is sometimes the best teacher! I've got some pictures and such but I'm going to do as you suggest and see if I can find the root cause of the problem and start there. It may be a combination or the true root cause may be causing other problems because it was overlooked or ignored for some time.

 

[Breezy1]

What is the engine, a 2GM-20F? Do not start replacing parts wholesale.

Hi Benny - Yes I'm going to check all of that out. It's worse than just an annoying vibration. I'll keep everyone posted when I do more investigation.

 

[Leeward Rail]

I'm going to do as you suggest and see if I can find the root cause of the problem and start there. It may be a combination or the true root cause may be causing other problems because it was overlooked or ignored for some time.

This reminds me of a recent post in an automotive forum. A vehicle had been in multiple shops with parts and labour thrown at it, that exceeded the value of the vehicle. All for a vibration when reaching a certain speed. The previous techs made assumptions without precise methodical diagnosis.

In the end, the original fault was found (cheap repair), along with an additional vibration inducing fault, due to "repairs" done to try "fix" the actual problem in the past.

 

[Breezy1]

Thanks to all of you. I think most importantly that I don't feel like I'm all alone when I go to tear into this! I really like this forum, even though I'm not so adept at responding efficiently! lol

 

[jssailem]

Welcome to mature boat ownership. You have a 20year old boat and already resolving “Stinks and shakes “. I’d say your on the right track.

As was identified above, don’t patch symptoms. Use them to identify the cause then correct the problem. Are you on the hard in this Michigan winter?

If so you have lots of freedom to inspect the parts of the propulsion system not given to those still afloat. Use it to your advantage.

Here is to hoping the problem is small like motor mounts.

What ever it is keep in mind the engine is auxiliary on a sailboat. It doesn’t need to be finely tuned like a race car, unless you want to spend money that way.

Sailing a boat can absorb gobs of money on the primary power source sails and the transmission method rigging. It is worth it to invest there.

 

[Ralph Johnstone]

It's really cold here in Michigan and I've got to get down to the marina and check all these things out,

I hope he didn't get to the marina and then freeze solid while checking out the engine .

 

[Breezy1]

Welcome to mature boat ownership. You have a 20year old boat and already resolving “Stinks and shakes “. I’d say your on the right track.

As was identified above, don’t patch symptoms. Use them to identify the cause then correct the problem. Are you on the hard in this Michigan winter?

Thanks for your post. Yes I'm on the hard so I can inspect all the underwater workings easily at this point.

 

[Breezy1]

I hope he didn't get to the marina and then freeze solid while checking out the engine .

I haven't gotten down there just yet, so I haven't frozen yet! lol I don't mind the cold but I'm not anxious to be working outside below freezing! I'm getting more anxious by the day. I need to put my plan and schedule together to get everything done in time to enjoy the summer.

 

[jssailem]

I need to put my plan and schedule together to get everything done in time to enjoy the summer.

I understand.
Prioritize the list of things to do.

1. Tasks the keep water out of the boat
2. Tasks that make the boat function
3. Things that would be fun to have but are not needed

Complete all of 1 then reshuffle and prioritize the remaining tasks into the last 2 categories for the time remaining.

As soon as you can take the boat out on the water. You’ll add more items to your lists and ignore some category 3 items till next winter. In the process you’ll have fun on your boat. Even if not “everything gets done”.

 

[Breezy1]

Priorities you've listed are very wise and definitely helpful. I find it is the time I've got to schedule, otherwise it will be mid summer and I'm still on the hard!!

 

[Ralph Johnstone]

I find it is the time I've got to schedule, otherwise it will be mid summer and I'm still on the hard!!

Remember that every job you estimate for time will be at least 5X as long with :

- forgotten tools
- can't source the material you need
- how the hell was this put together in the first place
- etc, etc, etc

You stated your original problem was the vibration @1800 RPM and this will involve mostly inside work. On your way into the boat, give the shaft a shake and see if the cutlass bearing is tight. If you have a 1500W heater, this can make the work tolerable. An Espar heater makes it a luxury. I think the vibration will be the longest project you will have.

 

[Breezy1]

Remember that every job you estimate for time will be at least 5X as long.....

Yea that's about right. It can be very frustrating especially with forgotten tools and short in materials. I do like the Idea of the heater for sure!!

 

[Ralph Johnstone]

If you don't mind, please share your finding as the mechanical end of these things always interests me.

 

[Breezy1]

If you don't mind, please share your finding as the mechanical end of these things always interests me.

Well I finally got down to the boat and started poking around. I disconnected the prop shaft from the trans expecting the engine to drop or do something and .......nothing. It seems well aligned. So it wasn't the smoking gun I was hoping to find.

My next step will be to remove the shaft and have it check for run-out and bend. Have the prop checked for equal pitch and balance. If I find nothing there, I'll go back to the mounts. I tried to inspect them with a flexible camera but it is really hard to see anything. Besides if I don't see any tears or whatever, I'm not sure how to tell if they are bad. Ughhhhhh. The joy of owning a boat! lol