30 HP Yanmar: Repower v. Rebuild?
 

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

30 HP Yanmar: Repower v. Rebuild?
 

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

30 HP Yanmar: Repower v. Rebuild?
 

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

30 HP Yanmar: Repower v. Rebuild?
 

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

30 HP Yanmar: Repower v. Rebuild?
 

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

30 HP Yanmar: Repower v. Rebuild?
 

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

30 HP Yanmar: Repower v. Rebuild?
 

"NE Sailboat" wrote in message
news:reush.9981$pb7.5843@trndny09...
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?


I have the 2QM15 and it still runs and starts well. But, if it failed I
would have the same decision to make.

I think that I would seriously think about installing a new fresh water
cooled engine with heat exchanger. My concern after 27 years would be with
corrosion of the block, and it is difficult to determine this. Maybe there
is a way once the engine has been torn down?

I think that if I was younger (your age), I might consider doing the rebuild
myself, but maybe not. These engines do have cylinder so no need for
reboring or oversize pistons etc.sleeves.

I would think that I would pay $10k for a new engine if a rebuild cost $6k.
But, if the rebuild could be done for say $3k, I would go that way. As a
comparison, I had a complete rebuild done on a used block on my old diesel
car - a 5 cyl MB 300D. It cost me C$7k which at the time was about US$5k and
this included removing the old engine and also installing a rebuilt turbo.
$6k for a 2 or 3 cyl Yanmar rebuild sounds like a lot!

30 HP Yanmar: Repower v. Rebuild?
 

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

30 HP Yanmar: Repower v. Rebuild?
 

Bob wrote:
....
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.


That sounds like a lot - I have a friend that replaced a tired 3GM
with a new 3YM and he claimed it was well under $5K. The footprint
was almost identical, I think there were a few changes for the
plumbing, but the job was done in a day. He didn't need a
transmission, and there was 100% access so YMMV. You should shop
around a bit before listening to one quote.

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????

30 HP Yanmar: Repower v. Rebuild?
 

Bob wrote:

The problem was the $6000 he quoted for the rebuild.
Thats a lot of money for a 30 yo motor.


Reluctant Bob


Geez, Tbat $6K should just about pay for a new
3YM30, and I'd bet the footprint is nearly
identical. You wouldn't have to rebuild the
stringers, but you might have to have custom
"vibration" mounts built to hit the bolt holes.

I'm in a similar situation except that I've got a
1983 3HM Yanmar sitting in the Irwin. It was
supposedly "overhauled" just before I bought the
boat, but overhauled can mean a lot of different
things depending on who is saying it. Right now,
it starts and runs great, so I'm going to let it
keep running, but I've already marked it down in
my mind as suspect for long voyages.

Have you gotten quotes on a new 3YM30? I'd also
think about going to fresh water cooling if I were
you.

Don W.