Looking for insight as to squeal under engine power

[Baysider]

Thanks Stu.  I'm learning little by little. That's why I'm asking the C34 community for suggestions as to what to check.  I agree that when you live with your boat you have better insight than someone who is a generalist, and I have sufficient mechanical experience that I'm not a "sit back and let someone else do all the thinking" guy, but there's also something to be said to bring in a mechanic who has the tools and experience to work on solutions.  Thanks for your advice!

[waughoo]

A quick search for prop sing showed a number of results.  This is one that had a bunch of explanations I found useful.

https://downeastboatforum.com/threads/prop-sing-phenomenon.32602/

[Stu Jackson]

Thanks Stu.  I'm learning little by little. That's why I'm asking the C34 community for suggestions as to what to check.  I agree that when you live with your boat you have better insight than someone who is a generalist, and I have sufficient mechanical experience that I'm not a "sit back and let someone else do all the thinking" guy, but there's also something to be said to bring in a mechanic who has the tools and experience to work on solutions.  Thanks for your advice!

You're right, we all started somewhere and none of was born a diesel mechanic.    What I learned in the last 25 years with this boat were a couple or a few things:

1.   We didn't have to actually be a diesel mechanic to service our engines.  I was SO scared of an inboard engine I put off buying one for 10 years!  Once I did, and with the help of this website, which was only in its infancy back then in the late 90s, I realized I was hopefully never going to have to crack the beast open and work on the guts, but that I could learn servicing and how to listen for anomalies - like you have. 

2.   In my mind, the phrase "diesel mechanic" has become an oxymoron.  In all my travels, I found it hard to find someone who'd actually had a good experience with one.  No one likes your engine as much as you do.  It's like folks who before they buy a boat go to a diesel class - my response has always been: "The ONLY diesel engine you should care about is the ONE in YOUR boat.  If you don't know that yet because you haven't bought a boat, you might well be wasting your time.  If you study a Yanmar in a Max Boring Class but you end up with a Universal, there are going to be significant differences of the things you will see and need to work on, and that class will be worthless in that regard."  In my 18 years in SF I learned of one, only one.  And in five years here in western Canada, also only one.

3.  Re: mechanics - the "2000 rpm" statement is what set me off about your "mechanic."  If you have dock neighbors and/or friends who recommended him, at least you got a referral, but I would do the "trust but verify" with this fella.

And yes, as time goes by, you learn more and more.  And I know that the respondents on this forum and the information on the rest of our website will be more than pleased to help you along.

Good luck, keep us posted.

[Baysider]

Thanks Alex. A very informative string on prop sing! I'll look into it.

And thanks Stu, but I hadn't said my mechanic felt the 2000 rpm speed was where the engine wanted to run, I said it was the POs and that the surveyor didn't find fault with that.  If I remember correctly, my mechanic told me I should be able to run comfortably at 85% of max engine speed.  That would put a comfortable engine speed at about 2700.

[Ron Hill]

Bay : Your mechanic was correct about the cruising RPM of a M25XP engine.  I always run at about 2600 rpm.

Stu is correct in that if you get a chance to take a diesel engine course I'd advise it.  If you can get it for a Universal engine all the better.  I was lucky to take a 6 hr. Universal M25 engine course way back in 1989 for $25!! One of the best things that I've ever done!! I had been an aircraft maintenance officer, but knew little to NOTHING about a diesel engine.  When I bought the boat the Catalina mechanic had just gotten out of the Army and had a good 3 year experience.  When he found out that I had retired with over 30 years I was able to really pick his brain during commissioning. 

Once in 1990 I hired a "diesel mechanic" to adjust the valves on my M25XP.  After only a few minutes I determined that I knew more about adjusting valves then he did - so I fired him.  I had a VW Bug convertible and adjusted those valves upside down on my back!! All you have to do is read the Universal owners manual and realize that you turn the engine (with the drive belt) while someone else (looking thru the inspection port on the fly wheel) when the cylinder is at top dead center. 

You may not want to get into that kind of detail, but diesel engines are really simple because they do not have an ignition system!!   You'll probably NEVER have to adjust the timing on your diesel.  The factory did that and it just does not tend to change - like a gasoline engine.  Diesels just need clean air and CLEAN fuel to start and keep on running!!

If your 3 bladed 9X15 prop is a Catalina issue sailor prop, there shouldn't be a problem with "singing"!!

Good luck in your quest to find that noise.  Like I said try a long shank screwdriver or a stethoscope (that's what mechanics do!!)

A few thoughts   

[Stu Jackson]

...

And thanks Stu, but I hadn't said my mechanic felt the 2000 rpm speed was where the engine wanted to run, I said it was the POs and that the surveyor didn't find fault with that.  If I remember correctly, my mechanic told me I should be able to run comfortably at 85% of max engine speed.  That would put a comfortable engine speed at about 2700.

Thanks, I went back a re-read that post.  If you do, too, you may see where confusion could arise as to who said what.  It seemed to me that the "mechanic" agreed with the limit, regardless of who may have said it.  Really doesn't matter, does it? 

And yes, I think all of us agree that ~2700 is good.