I've got what I think is a bad engine vibration with my C34. I've assumed that the problem is that it needs new engine mounts. However, this weekend, I got a little more serious about the new mount project and spent some time looking it over. I'm starting to question whether the mounts are the problem.
The vibration is the same whether it's in or out of gear, so I don't see how it could be alignment. I'm starting to think that the engine may be in a bind.
If you try and move the engine, it's almost like it's bolted directly to the stringers. When the engine is running, it hardly moves at all on the mounts. It could be that the mounts are so far gone that they have not give to them. Or it could be that it's bound up on the mounts.
Any advice would be appreciated.
Jack
Jack : You have the original engine mounts!! That port side forward mount is probably shot from oil while changing the filter. I'd change all of the mounts and you'll have a NEW engine!!
A thought
New mounts would likely be a good place to start. As the rubber ages, it hardens and collapses which effectively gives you no isolation from the hull.
Quote from: Ron Hill on March 31, 2025, 01:33:31 PMJack : You have the original engine mounts!! That port side forward mount is probably shot from oil while changing the filter. I'd change all of the mounts and you'll have a NEW engine!!
A thought
Sounds good.
It seems like in most of the pictures on this site, the mounts look bad when they are shot. These mounts look fine. No evidence of rust or oil, but they are quite old.
If you can believe the Hobbs meter, and I think you can, the engine only has around 500 hours on it. I can see where the mounts could be bad just from age and supporting the engine for 37 years. But again, they look just fine.
I can't see any harm in replacing the mounts, they are fully depreciated.
Thanks for the replies.
Jack
Jack
You'd need to observe / video the mounts with the engine vibrating to get a fair picture of what's going on. If there is no movement in the mounts' rubber then the vibration is being transferred directly to the stringers.
Jack : Those mounts are 37 years old. I change out my original mounts back in about 1997/8?. It was the BEST mod that I have ever made to my C34 - It was like I had a new engine, it ran so smoothly!!
You holding out for 50 years before you change the mounts???
A few thoughts
Quote from: Ron Hill on April 03, 2025, 02:09:51 PMJack : Those mounts are 37 years old. I change out my original mounts back in about 1997/8?. It was the BEST mod that I have ever made to my C34 - It was like I had a new engine, it ran so smoothly!!
You holding out for 50 years before you change the mounts???
A few thoughts
Ron
I'm not holding out, I'm perfectly willing to replace them. I've got the receipts to show how much love I've lavished on my boat.
It just seems to me that the problem might be that the engine is bound up on the mounts, not the mounts themselves. I've found lots of posts on this forum where old mounts seem to be Ok if not great. I have not found anyone who has my symptoms; the engine does not move at all.
I could see where old mounts might become too soft or where they might become hard and not let the engine move enough. The fact that my engine won't move on the mounts at all seems like a mechanical bind. I'm fairly certain something is going on beyond the mounts being old.
Having said that, replacing the mounts and a fresh alignment will almost surely fix the problem. That's what I'm going to do.
Thanks for the replies; I'll report back.
To throw another perspective into the mix: my boat is a 1990 with just 750 hours on the engine and the motor mounts are working fine. So, my takeaway—-year built, while something to consider, doesn't always determine the lifecycle of boat engine parts.
Quotereplacing the mounts and a fresh alignment will almost surely fix the problem. That's what I'm going to do.QuoteThink that's sound thinking. Also consider a new cutlas bearing at this point. I don't think that a good alignment is possible without one.
Jim
QuoteTo throw another perspective into the mix: my boat is a 1990 with just 750 hours on the engine and the motor mounts are working fine. So, my takeaway—-year built, while something to consider, doesn't always determine the lifecycle of boat engine parts.
It's been my experience that rubber parts can get old just sitting on a shelf. I just googled tire exploration, and the recommendation is 6 years, that's shelf life.
Just my 2 cents,
Jim
I get it with tires, as there are liability/safety issues involved. Engine mount/vibration, not so much. But it could be? I would be rich today if my wife didn't zealously throw away everything in our house that had reached its manufacture's "best if used by" or "expiration" dates printed on the packaging. ;-)
I've decided to replace the engine mounts and I'd like to get it done before the sailing season gets into full swing.
I thought picking the mounts would be easy: Vetus K50s on the front and K75s on the back. However, now that I've done a little more research, I find that some people are not happy with that setup.
https://c34.org/bbs/index.php/topic,1344.15.html
The complaint is that some get serious vibration at low RPM.
Does anyone have any insight into what's considered the "best" setup? A lot of the comments about problems with the Vetus mounts are old. Perhaps there is something better out there in 2025.
Any advice would be appreciated.
Jack
Jack : Many years ago I replaced all of my original engine mounts with Vetus K50s. I found out that the K50s were a bit too soft so I changed out the REAR mounts to K75s! That solved the problem. I didn't change out all to K75s for $$ reasons and suspected that the K50s in the rear were the problem!! Which they were!!
I'd recommend that your change to all K75s and you'll be OK!!
A few thoughts
Quote from: Ron Hill on April 09, 2025, 02:57:47 PMJack : Many years ago I replaced all of my original engine mounts with Vetus K50s. I found out that the K50s were a bit too soft so I changed out the REAR mounts to K75s! That solved the problem. I didn't change out all to K75s for $$ reasons and suspected that the K50s in the rear were the problem!! Which they were!!
I'd recommend that your change to all K75s and you'll be OK!!
A few thoughts
Ron
Thanks for that advice. That's what I'm probably going to do.
What do you you think of simply going back with the factory mounts? They are expensive from Catalina Direct, but if they work the best then that still makes sense.
Thanks
Jack
Quote from: Carbon on April 10, 2025, 12:11:42 PMThey are expensive from Catalina Direct, but if they work the best then that still makes sense.
First of all, never buy DF isolators from CD. Buy them direct.
Second, where did you hear that "they work the best"??
Folks change them out FOR A REASON. It would be simple to replace same with same one.
Don't overthink this. K75s all around!
Jack : I can't overstate how pleased I was when I change out from the OEM mounts. It had gotten to the point that in a long motor I would stand on a rubber cushion to prevent the "buzz" that was being transmitted to my feet.
I've had dockmasters and marina owners ask (when I told them to throw off the bow lines) "aren't you going to start your engine"?? It was already running !!
A few thoughts
Quote from: KWKloeber on April 10, 2025, 02:18:21 PMSecond, where did you hear that "they work the best"??
Don't overthink this. K75s all around!
I didn't say "they work the best", I asked "
if they work the best".
Logic would say that when these boats were new they must have had reasonable engine vibration. Otherwise Catalina would have done something different because it would have affected sales. Presumably stock engine mounts would put it back to like new levels which are probably pretty good.
My other boat has a Yanmar 30Hp 3YM engine on stock Yanmar mounts. It's very smooth at idle and at motoring RPM. My experience in Yanmar world is that the stock mounts work well, I've never considered upgrading them to something better.
If the current consensus among C34 gurus is that Vetus K75 mounts work best, then that's an easy decision. They are not very expensive and in stock at Defender.
I do have a quote request out to a company called Oceanic Innovations. They make engine mounts, mostly for Yanmar, that have stainless and urethane construction. They don't stock mounts that will fit the M-25XP, but they have made them in the past. It would be a special order item, delivery might be a problem.
Urethane is unaffected by oil & diesel. Stainless obviously beats mild steel for rust. I'd like to see that quote. But, I've been waiting nearly a week for the quote, not sure it's ever going to come.
https://oceanicinnovations.store/collections/frontpage?gad_source=1
Jack
The original mounts do not provide the same isolation that the vetus ones do. I suspect you would not notice the same improvement in sound transmission to the hull if you did the stock mounts vs the vetus.
The Yanmar mounts (especially when coupled to a sail drive) are particularly good at isolating vibrations. I suspect they spent more engineering resources to this part of their marinization vs Universal.
Jack
Gotcha. Now I understand what you meant, but that was a statement not a question, i.e., no "?", there.
The key issue with the OEM or other isolators is a leaky seawater pump that conveniently runs right onto that forward one. If there's diesel and else getting to mine I have more of problem! I'd expect a custom fab to be super costly, but I hope you get a quote so we know.
As far as the factory and OEM mounts, the fact is that Frank, like any production boat builder, cost was key and also remember supply chain availability. One could say similar things about the Univesal's wiring, exploding alt mount, and other shortcomings -- or Catalina's own harness, the infamous Catalina port list and "off-plumb" keels, etc. They did not seem to affect sales, only complaints long afterward. Like 20 years later.
-Ken
Quote from: Carbon on April 11, 2025, 08:41:14 AMQuote from: KWKloeber on April 10, 2025, 02:18:21 PMSecond, where did you hear that "they work the best"??
Don't overthink this. K75s all around!
I didn't say "they work the best", I asked "if they work the best".
Logic would say that when these boats were new they must have had reasonable engine vibration. Otherwise Catalina would have done something different because it would have affected sales. Presumably stock engine mounts would put it back to like new levels which are probably pretty good.
My other boat has a Yanmar 30Hp 3YM engine on stock Yanmar mounts. It's very smooth at idle and at motoring RPM. My experience in Yanmar world is that the stock mounts work well, I've never considered upgrading them to something better.
If the current consensus among C34 gurus is that Vetus K75 mounts work best, then that's an easy decision. They are not very expensive and in stock at Defender.
I do have a quote request out to a company called Oceanic Innovations. They make engine mounts, mostly for Yanmar, that have stainless and urethane construction. They don't stock mounts that will fit the M-25XP, but they have made them in the past. It would be a special order item, delivery might be a problem.
Urethane is unaffected by oil & diesel. Stainless obviously beats mild steel for rust. I'd like to see that quote. But, I've been waiting nearly a week for the quote, not sure it's ever going to come.
https://oceanicinnovations.store/collections/frontpage?gad_source=1
Jack
Guys : The engine mounts come with the engine!! No boat builder is going to put different engine mounts on a new engine and discard the ones that came with the engine.
Ken you forgot the port side forward mount is below the Oil filter. Unless you take EXTREME CARE changing the filter - there will be old engine oil on that mount - which will Kill it!!
A few thoughts
Thaanks Ron
I forgot about the isolators being delivered by Universal. I'm not sure that in those years, K50s and K75s were even made. Do you know?
On the drips, I wasn't including things that are under OUR control. Sure, I could spray diesel onto all of them if I was careless about changing a fuel hose. I'm thinking that most? owners will be conscientious about not destroying isolators.
Quote from: Ron Hill on April 11, 2025, 03:04:35 PMGuys : The engine mounts come with the engine!! No boat builder is going to put different engine mounts on a new engine and discard the ones that came with the engine.
Ken you forgot the port side forward mount is below the Oil filter. Unless you take extreme care changing the filter - there will be old engine oil on that mount - which will Kill it!!
A few thoughts
I changed out Eximius' Mounts with K75's around 2016, in 2024 Vibrations returned in 2024 so I replaced them again.
Didn't solve the issue, actually it was worse.
Had a mechanic check it out and he figured it was the Damper Plate. I replaced that and the vibrations / noise dramatically reduced. The old damper plate was shot, the springs were intact but were no longer providing any decent physical connection from the Flywheel to the Gearbox input.
I had never heard of a 'damper plate' prior to this.
Paul
Hi Paul, what manufacturer and part number did you use for the replacement? How many hours do you have on your M25XP? Thanks.
Jon : Look in the Mainsheet tech notes. When I changed to a Hurth 100 on the old M25XP I also changed to a new damper plate. I believe I mentioned the Model Number and the source.
A thought