Let the debate begin........

Repower for the 21st century
Or
Rebuild a 1979 Yanmar 3QM30H (raw water cooled)?

Lets assume the engine is DOA and must be either replaced or rebuilt.
My first experience with replacing an engine was attempting to shovel a
huge Cadillac engine into a Nova. Boys will be boys. Lesson learned:
Lots of adjusting and cutting. But hopefully those who have actually
repowered a 34'-41' keel boat learned a few lessons from their
choice.

This is not a troll. I seek your advice with the greatest sincerity. So
be brutal or humble or descriptive adn I'll gleen what I can.

After reading my latest issue of Boats & Harbors I wish I had a 6-71.
Either way it would be cheaper than my little 27 hp Yanmar. Go figure.

Cordially,
Bob

My thought .. the engine fits the stringers, and therefore it would be easy
to take out and put back in.

So,, why not just get the engine rebuilt.

Can't you take it out, bring it to a rebuild place, get it all done over
with new this and new that .. then bring it back and put right back where it
came from?


"Bob" wrote in message
ups.com...
Let the debate begin........

Repower for the 21st century
Or
Rebuild a 1979 Yanmar 3QM30H (raw water cooled)?

Lets assume the engine is DOA and must be either replaced or rebuilt.
My first experience with replacing an engine was attempting to shovel a
huge Cadillac engine into a Nova. Boys will be boys. Lesson learned:
Lots of adjusting and cutting. But hopefully those who have actually
repowered a 34'-41' keel boat learned a few lessons from their
choice.

This is not a troll. I seek your advice with the greatest sincerity. So
be brutal or humble or descriptive adn I'll gleen what I can.

After reading my latest issue of Boats & Harbors I wish I had a 6-71.
Either way it would be cheaper than my little 27 hp Yanmar. Go figure.

Cordially,
Bob

NE Sailboat wrote:
My thought .. the engine fits the stringers, and therefore it would be easy
to take out and put back in.

So,, why not just get the engine rebuilt.

Can't you take it out, bring it to a rebuild place, get it all done over
with new this and new that .. then bring it back and put right back where it
came from?

Yes, that was my thought too. But there are some folks that say
"upgrade" to more modern model. ANd then mention part availibility
problems on 30 year old models. But when I went to my local tractor
dealer they didnt blink an eye when I asked for a rebuild quote on a
marine qm yanmar. The problem was the $6000 he quoted for the rebuild.
Thats a lot of money for a 30 yo motor.

But when I think of trying to modify an existing space for a diffrent
engine I start having flashbacks of a cutting torch and endless detail
modifications. I really like the idea of an exact foot print...... easy
out easy in. But????

Reluctant Bob

How old are you?

If this is a sailboat engine, there is a good chance you won't still be
sailing by the time it needs another part after a complete rebuild.

--
Roger Long

Roger Long wrote:
How old are you?

If this is a sailboat engine, there is a good chance you won't still be
sailing by the time it needs another part after a complete rebuild.

--
Roger Long

Damn good point Roger.
Im 53. The boat, built in 1979, & 3QM are 26 yo.
So if it lasted 26 the first time I really should not need to worry
about the second rebuild...............?
Bob

I'm 56 and my 1980 Yanmar 2QM20 runs as well as I would expect a brand new
engine to run.

I'm not expecting to rebuild it either.

--
Roger Long

Bob wrote:

But there are some folks that say "upgrade" to more modern model.

Modern isn't always better. I don't know what is going on with small marine
diesels now but I fear my recent experience with aircraft maintenance may be
relevant to boats. If anyone has data to add on these points, I'd
appreciate hearing it.

In aviation, things that used to last for hundreds of hours a couple decades
ago began failing very rapidly about a decade ago. This applies to vital
engine parts like valve lifters and camshafts as well as flight instruments.

The reasons are all the globalization issues. A turn coordinator used to be
built in a place where someone who had been assembling them for 20 years
knew that if one part swung back and forth just a certain way when trial
assembled, it was good to continue. Otherwise the parts needed some
tweaking. The company gets bought by someone who thinks they can make a
profit by increasing effeciency so they fire everyone and hire younger
people who will work for less. All they know is that part A goes into part
B and they have to assemble 20% more than the old crew did or they'll be
looking for a job.

There is a specification and a procedure for heat treating valve lifter
faces. Somebody, or a crew who has been doing it for a long time, knows
something like the fact that letting the kiln cool down with the parts in it
instead of just taking them out is the difference between parts that fail
prematurely and those last. This never makes it into the specification
because it's just the way they've always done it. The company gets sold and
the production is moved to China where they follow the specifications to the
letter but the parts still start failing half way to overhaul time.

A lot of things like engines were designed to be built by artisans who cared
and understood them and have not made the transition to modern times
gracefully. A thouroughly modern engine built on a thouroughly modern
production line with the advantages of computer machining, etc. may be
better. Automotive engines certainly are. I'm not sure that something like
a small marine diesel is better simply because it's a newer model.

If I were replacing an engine in an aircraft and strapping my butt behind
it, I would prefer an engine overhauled by a good overhauler who looked at,
evaluated, and adjusted, each part individually than a brand new one from an
assembly line. I'm not sure this hold true for boats but my first
inclination if I had your engine would be to go for the overhaul.

--
Roger Long

"Roger Long" wrote in news:45b281b7$0$28089
:

All they know is that part A goes into part
B and they have to assemble 20% more than the old crew did or they'll be
looking for a job.


It's the reason Mercedes Benz no longer produces the finest automobiles in
Stuttgart, but builds a piece of SUV crap in Arkansas with the company
logon on it.

They are no longer listed on "The finest cars in the world" lists.....

Don't think so? Search google for lemon MB SUV models....Man those owners
are ****ED!

Larry - 1973 220D....simple, efficient, no electronics or computers.
--
Democracy is when two wolves and a sheep vote on who's for dinner.
Liberty is when the sheep has his own gun.

When I took over the management and maintenance of the 172 I used to fly,
the original turn coordinator installed in the panel in 1976 was still in
the plane. By the time I stopped flying five years later, we had put two
new ones in. Same design from the same company. Workmanship is as important
as design.

Much of the resdesign you talk about is intended to make workmanship less
important in the quality of the final product. It certainly does that. No
matter how good or bad the workmanship is, the product is still a piece of
crap!

--
Roger Long

Roger Long wrote:
Bob wrote:
But there are some folks that say "upgrade" to more modern model.

Modern isn't always better.
Roger Long

Hi, good point.
I had a conversation with a shop manager at my local GM (car) dealer.
My 1994 car toasted a
heater blower switch and had it replaced in 2000. It failed after 2 ½
years. I put in another one and it failed after 3 years. Each was
genuine GM parts from my genuine GM dealer.

The shop manager explained to me that engineers use computers now and
design more efficiently (insert wise crack here). These efficient
designs reduce the once common and expensive practice of over building
parts that contained wasted potential and added to unwanted weight and
increased costs. My response was, and reduced unit reliability! No
response from the shop manager.

I like to keep things simple. A rebuild and easy replacement sounds a
lot les frustrating than hoping for a similar foot print and all the
potential adapting. My motor lives under the sink in the middle of my
galley. I aint got but an inch any way around for clearance. Great for
engine access when I pull all the covers but I imagine a bear to make
something different fit.

But scheesh... when I sell the boat in 20 years who is going to buy a
boat with a 50 year old motor obviously with at leaser one rebuild?!?!

**** that statement is dumb, who is going to buy a 50 year old boat!?!?
Bob