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Old 19-04-2020, 12:41   #76
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Re: How many hours is too many?

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Originally Posted by mvweebles View Post
Sounds like seeing if engine starts promptly when cold should be easy. Also, I was mistaken in one item: garden hose should NOT be hooked up to the intake of the water pump">raw water pump directly. As someone else mentioned, the intake should be put into a bucket, and the bucket filled with a garden hose. This will prevent back filling the exhaust and allowing water to enter the exhaust side.

I'm curious. How does a 1991 Catalina 30 that is laid up for over half the year accumulate 4000 engine hours? Cruised to the Bahamas a few years? Normally, boats like these do not have much noise insulation and this isn't a particularly smooth engine so it's not exactly something that would endear itself to long motoring. 4000 hours is equivalent to over two years of full time 8-hr/day work. Just seems like an unusually high number of hours on a boat like this given its laid up half the year.

Just curious. Not a huge deal.
And right there you hit it on the head. That's part of what started this whole conversation; the other part being how to evaluate an engine with those hours.

It's seen 6 months of sea water apparently. So, how does a boat that's never left the St Lawrence or Great Lakes from Toronto, have 4000 hours in 29 years? Motor up and down the St Lawrence a few times, charge an iPad, and nuke some popcorn while anchored in a secluded bay?

Especially, when you compare to other C30's in the same sailing area that have not even half of that, and are in some cases 5 years older. Maintenance unknown, but these are at least freshwater boats that presumably have the same usage profile.

There is one other boat on the US side that is more cash, but a few years newer, looks well maintained as well, 1/5th the hours. There is the trouble of importing though. Not insurmountable but another headache and closed borders to moving a boat I'm assuming at this time.

I've also been looking into other things the last few days, and I've uncovered the need for rigging replacement, more frequently than every 29 years... not sure if this applies to fresh water boats as strictly, but I also get the impression that newer is generally better, and paying more upfront for a better condition boat is a lot cheaper than fixing them.

There is also rebedding of chainplates I've discovered! LOL I'm happy for advice on rigging and rebedding with respect to evaluating condition as well. I probably should have started a thread title 'Help Peter Understand xyz'....

I'm learning, I'm learning...
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Old 19-04-2020, 13:36   #77
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Re: How many hours is too many?

Going back to the original question, who made the engine and how was it maintained.
Was it used for the correct duty cycle. I oiled on a tug, summers going to college, Twenty hours a day was the norm. I got paid an extra hour to have it up to temperature. Cold starts and running the hell out of one could be a killer. This was a big piece of iron, 12V567, so maybe more important with a small piece of iron?
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Old 19-04-2020, 14:50   #78
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Re: How many hours is too many?

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Going back to the original question, who made the engine and how was it maintained.
Was it used for the correct duty cycle. I oiled on a tug, summers going to college, Twenty hours a day was the norm. I got paid an extra hour to have it up to temperature. Cold starts and running the hell out of one could be a killer. This was a big piece of iron, 12V567, so maybe more important with a small piece of iron?
In OP, states M25, which is a Universal 20hp 3 cylinder. These engines do not have duty ratings the way that larger engines do. It was made for sailboats of this size and was quite ubiquitous during the 1970s through early 1990s when Yanmar dethroned Universal at the small end, and Perkins at the medium end (say, under 100 hp). They were a very popular replacement g and upgrade for Atomic 4 gas engines. Another post on this thread said Universal used Kubota power plants. I have no idea.
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Old 20-04-2020, 04:07   #79
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Re: How many hours is too many?

Internet search shows that the M25 is a marinized Kubota D850. So parts should be available perhaps.
To the point of 4000 hours, that’s 100 hours per season. I think breeze is spotty in Great Lakes? I put 100+ per season on my boat in 6 months per year part time cruising-
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Old 20-04-2020, 05:25   #80
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Re: How many hours is too many?

The reason for duty rating of an engine is to meet a specification of life limit, many decry the statement that light duty Marine Diesels are often manufactured with a 5 to 8 thousand hour life limit but it is most likely true.
An engine manufacturer who is given a contract to provide engines that meet certain specifications will very, very often meet the specs if it’s a higher than normal average life limit simply by taking a current production motor and turning the RPM and therefore the max power it can make down, engines that are operated under lower stress often live longer.

If there has been no requirement to provide an end to meet specs like that you often won’t find different duty ratings, cause there is no need, it’s not that that it’s not possible for that engine to have a longer life expectancy with lower limits, it’s just that it wasn’t required.
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Old 20-04-2020, 08:29   #81
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Re: How many hours is too many?

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Marine engines and generators have design ilfe of 5,000 hours.
Really? Where's this information from? Just sold a small tug that had a couple small generators the newest one had 23k and the older one was just over 30k. Once inspected and tested both were given the green light by Transport Canada. It's all about maintenance. There is no hard and fast rule and often it doesn't seem to matter what name is on it as most are owned by the same large makers on some level.
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Old 20-04-2020, 08:31   #82
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Re: How many hours is too many?

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A verry strange statement ,as a diesel machanic with over 50yrs in the marine trade ,a shipwrights boatbuilder ,trade trained qualified diesel fitter ,mechanic ,I am verry interested where this sweeping statement is based ,have seen small twin Volvo penta ,driving an irrigation pump,running like a clock at 24k hrs no electrics hand start ,also a air cooled lister 3 cyl gen set running for 9 yrs with verry little maintaince,and an 8l3 Gardner in an 80 ft trawler at 90k hrs still strong ,. Maybe some small turbo charged highly stressed poorly maintained engines will have a short life ,look after them and they will look after you .,i
👌👍. What they said.
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Old 20-04-2020, 14:59   #83
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Re: How many hours is too many?

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Internet search shows that the M25 is a marinized Kubota D850. So parts should be available perhaps.
To the point of 4000 hours, that’s 100 hours per season. I think breeze is spotty in Great Lakes? I put 100+ per season on my boat in 6 months per year part time cruising-
That's correct, it's a Kubota D850 and parts are readily available including a Manifold heat exchanger from Thermex. Alternatively, a rebuilt D850 is about $1700 but thats the industrial version so you'd have to either swap the marinization parts over or buy new. Also the D950 is the same block only bored out a bit. They're very gutsy engines being an over-square design. Most of the torque come on low in the rpm range.
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Old 20-04-2020, 15:21   #84
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Re: How many hours is too many?

I don’t know why you guys refuse to listen to what a design life limit is.

So what do you guys think a designer, designs to? The maximum life possible? Of course not, but they don’t often design for the cheapest to produce either, there has be something in between, so they do in fact have a design life, which allows a manufacturer to manufacture as cheaply as they can, but their engines still last long enough so that their reputation isn’t tarnished, usually, sometimes they get it wrong.
For example for my IO-540W1A5D aircraft engine, it was 2500 hours, but when I tore mine down at 2500 hours, all the “hard” parts met new specs, not serviceable specs, but the specs for a new part, so my engine could well have gone much, much longer than it’s design limit, because it was well maintained and operated conservatively.

Design life doesn’t mean how long something will last, it is how long it was designed to last under a specified mission profile.
Again, it’s a lot like tires, you can buy tires that are rated for 30,000, 40,000 miles etc. that doesn’t mean that is exactly how long they will last, a kid may wear out a set of 30,000 mile tires in less than 10,000 miles, where as Grandma may easily get 50,000 miles out of them, but they were designed on average to last for 30,000 miles, and I bet that on average, most do.
Engines are the same way.
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Old 20-04-2020, 15:29   #85
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Re: How many hours is too many?

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So:
1) First engine check is cold start.
2) Second check would be exhaust
3) Third check is blow by.
4) Fourth check is underway sea trial.
5) Finally, oil analysis.

The above is pretty reasonable to do. A compression test, which messes with someone else's engine, seems like a big ask. Can these test be run (other than sea trial) on the hard?
Oil analysis is good mostly for comparing to previous oil analysis. I did it a couple times boat buying years ago, but that's what they told me.
Once it's warmed up, check that exhaust color too.
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Old 20-04-2020, 15:52   #86
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Hours for a Mann diesel

Along the lines of how many hours, my son-in-law is looking at a sport fisherman with Mann 1550 engines and is trying to find out how many hours they can typically go before needing an overhaul. Information he has been able to find so far on their web site just indicates maintenance requirements for various procedures like oil changes, valve adjustments, etc up to 4000 hours but nothing beyond.

Any Mann experts around?
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Old 20-04-2020, 16:09   #87
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Re: How many hours is too many?

the only thing i know about MAN marine diesels less than abt 5000bhp is that there is only one N in MAN (Maschinenfabrik Augsburg-Nürnberg AG)

cheers,
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Old 20-04-2020, 17:08   #88
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Re: How many hours is too many?

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the only thing i know about MAN marine diesels less than abt 5000bhp is that there is only one N in MAN (Maschinenfabrik Augsburg-Nürnberg AG)

cheers,
I knew that.
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Old 20-04-2020, 17:09   #89
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Re: How many hours is too many?

I am certainly no Man expert, very far from it, but I’d agree with 4,000 hours being about it for any larger Sportfisherman, that is actually a big number, many don’t make that. It’s not that they are bad motors, very far from it, it’s that they are very often run very hard. IF you can find one that wasn’t run like it was stolen then that is of course different, but most are run hard
What is interesting is to see the life difference between a DD 671 without a turbo, and the same motor with a turbo.
It’s not the turbo that kills them, it’s the extra HP that the turbo makes that kills them
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Old 20-04-2020, 17:15   #90
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Re: How many hours is too many?

I ran into a nice couple on a 65’ Viking Sportfish in the Dry Tortuga’s a few years ago and helped their Pro Capt fix a problem, Huge Man Diesels, In an airconditioned engine room.
I asked them what the cruise speed and fuel burn was. Pretty sure it was 25 kts and I know 120 GPH.
So of course it was a much bigger boat than mine, but to go four times as fast meant that they burned more than 120 times as much fuel.
So I asked how much fuel do you carry, I forgot now but I thought about it after he told me and I said you can’t even get across the Gulf then. He asked what I meant, I said you can’t even go from Clearwater to Panama City.
He said of course we can, we just go 8 to 10 kts and we can.

On edit, I think they may have been MTU’s
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