Overhaul engine now or wait for symptoms?

[Geek_Guy]

Tetra,

I purchased a 1987 a few years ago with nearly the same engine. I was and still am a little nervous.

I had a Yanmar tech come to the boat before I bought it. He started and determined that it and the transmission were at least usable. That only cost 200 dollars. Then I had him come back and check back through it, change the fluids, etc. He said he'd go to the Bahamas tomorrow on it.

I think the important thing to understand is that these engines aren't throw aways like we are used to with a car. They run and run and run. Even after 28 years they are often fully serviceable and dependable.

[Geek_Guy]

AND I have many great reasons for buying the 27 year old boat. I love the style of it. The price is way down there. It's comfortable and usable. We love upgrading and fixing it up. It makes it feel like our boat.

It is not just a hull. Most everything worked and it was immediately functional.

[UNCIVILIZED]

Originally Posted by sailorchic34

Having personally rebuilt my 3gm30F three years ago, parts where not that bad, cost wise. About $700 for rings, bearings, major gaskets, and one piston. I though the parts were fairly reasonable. Well the engine mounts were $150, which was spendy. But most parts are not too bad. Yes a Coolant pump or starter can be big bucks if new, but much less so having it rebuilt in a shop.

Now what is a pain, at least in California, is you must buy the parts from the local yanmar dealer, which may be a several hour drive away. Then they have to order the parts from the Georgia warehouse which is shipped to the distributor in Socal and then to the local guys. So I ended paying two shipping bills which is a pain (Come on Yanmar, its 2016, not 1950).

Of course if you have a marine engine guy rebuild an engine, it would be way too much. Matter of fact, one of the local yanmar shops said they had never removed a crankshaft (needs a special tool) which means most just repower for $10k ish.

I did the rebuild for $1200 including $300 for the machine shop and $80 for the special tool to be fabricated. This in 2013. I have a simple set of tools, used a oil filter wrench for a ring compressor, type of set.

A simple engine to work on, even if your blonde. Though I should clarify that I am an engineer and have a knack fix'n things

Impressive! Both your $ saving skills, & your tool wizardry. BTW, what exactly did you do during your rebuild? As that term can encompass quite a lot of things. And did you do the work in an engine shop which has all of the necessary tools, measuring & calibration devices, etc.? Also, how tough was it for you to get the engine (& transmission?) out of the boat? Given that as often as not, it's easier to cut out the cockpit floor for this part, & then re-glass it in place, once the engine's back in the boat.
I'm curious too, as to why it needed rebuilding?

Seeing planned obsolescence being circumvented surely gives me a smile. No joke. As I hate the concept. And especially when manufacturers, including Yanmar, purposefully cheapen their products so that they'll wear out quicker, & folks will be forced to buy new ones.
Especially when they switch over to more complex, non user servicable, parts. Such as the electronics on their newer engines, that regulate the engine's operation, in lieu of the older mechanical setups. Which just happen to be easier to fix, especially when you're leagues from the nearest FedEx hub.

[captlloyd]

Originally Posted by sailorchic34

If it starts easy, it's probably fine. The Yanmar 3gm's are fairly well built engines and will last a long time with proper care. Odd's are it has somewhere around 2500 hours, give or take 2000 hours. They should easily do 8-10K hours, if properly cared for.

Things I would check and or do..
1. External oil line in front of starter, behind alternator. They are prone to rust out infront of the starter, a known issue. If it looks at all rusty replace it. Yanmar has a copper replacement for $60 ish. Get extra crush washers as it can be tricky to replace without donating a crush washer or three to the bilge.

2. Change raw water impeller and check clean discharge elbow of carbon and mineral buildup. Most boats for sale, sit a long time and the raw water impeller tends to break in the first 10 hours of ownership.



3. Change belts, hoses and fluids. New hose clamps too


Easy check, with the engine idling, one at a time, pull each cylinders decompresson lever for a second or two and listen to the noise it makes, then close it. If the noise is equal across all cylinders then odds are the engine is working well with no head of valve issues. If the noise does not change as much, that cylinder may have an issue.

If the engine starts easy, compression is good. BTW a 3gm in cool climates can be hard to start. Need to set the throttle 1/3-1/2 open to start when cold and then set it back to idle once it's running. The 3GM's are straight compression engines without glowplugs.

What she said.

[Squanderbucks]

"Seems this thread pretty much covers the gamut of personality types: Preventive People" and those who "Run it till It Breaks and then Fix it".
I'm one of those who goes with the Preventive Group. Things seem to break the most when and where you need them the most. You can never stop it all but some things are pretty predictable, impellers, belts, hoses, etc. When getting a boat or engine that has some time on it and a questionable service record I would consider replacing anything rubber before any serious use (trips).
Change fluids, hoses, belts, clean air cleaners, all at bear minimums.

[sailorchic34]

Originally Posted by UNCIVILIZED

Impressive! Both your $ saving skills, & your tool wizardry. BTW, what exactly did you do during your rebuild? As that term can encompass quite a lot of things. And did you do the work in an engine shop which has all of the necessary tools, measuring & calibration devices, etc.? Also, how tough was it for you to get the engine (& transmission?) out of the boat? Given that as often as not, it's easier to cut out the cockpit floor for this part, & then re-glass it in place, once the engine's back in the boat.
I'm curious too, as to why it needed rebuilding?

The 1994 gm engines had a bad run of pistons and the ring lands would break which would cause all the rings to break. This is what happened to me. Of course I ran it for almost a year like that so the cylinder wall was scored badly too. Though it only cost about $100 more for machining a new sleeve into the block

Disconnection all the hoses, wiring, etc and removing the engine took a week. I used my main sheet blocks and boom vang blocks to hoist the engine (I had a few guys do the heavy lifting. We pulled it into the cabin and then up and out. Took 30 minutes to get it out. I have a v-drive so the engine had to come out into the cabin to get the prop shaft out of the transmission lower unit.

Engine was disassembled down to bare block. Disassembly took 2 days, well really a week as I had to have the special socket to remove the inner crank nut made.

Machine shop took 5 days from drop off to pick up. They bored and installed a sleeve and did a light honing to the other two holes. Assembly took 2 days and I spent another day or two cleaning the engine bay and replacing some hoses.

This happened at 1100 hours. Engine ran fine until it started to use more and more oil (up to a quart in 12 hours) and had high blowby. It also got harder and harder to start. At that time there was no measurable wear in the rings or bores of the other two holes or bearings. The old rings measured within new ring tolerances. Though I installed new rings and big end bearings. I did not touch the head as that was fine. I also did not touch the crankshaft bearings as the front and back needed additional special tools and they measured as new.

The engine now has 500 hours on it in 3 years time and still runs like a top. All assembly was done in the cockpit on two 2x6's across the cockpit. I had a small tool bag of tools and had a friend give me a MAC torque wrench. I built it myself, though I had the service manual.

NOTE: I did not touch the injection pump or injectors. The injection pump does need a spotlessly clean work bench.

All together it took a month from start to finish. Parts were $700 including two $150 engine mounts. It was a lot of work, but I saved tons of money I did not have.

You can read about my summer of discontent here: http://www.cruisersforum.com/forums/...ar-107705.html

[CdS2 Roland]

Hello,
You could mesure compression and do an oil analyze.

[lockie]

Leaving aside the engine for a moment, I strongly support grantmc's analysis.

Even if you can supply all the labour yourself, and have the skills, and do not lose income as a result of all this boat-time, the cost of parts and materials will add up at a frightening rate. Your estimated manhours will also obey the yachting axiom of doubling or tripling.

Before I bought mine, I considered two final boats of the same type and age. One was in great shape, well equipped and fully functional. The cheaper one was minimally equipped and had several items not functional. I added up the retail cost of required materials and added it to the asking price, and it far exceeded the price of the good one. The owner pretty much laughed when I told him what he'd have to drop his price to make it worth my while. So I bought the good one, which meant I could sail on day 1, and am very pleased at my decision.

Don't buy a project, unless you have the experience to accurately (ie pessimistically) cost it time and dollar-wise.

Back to the engine, my 2GM is nudging 2K hours at 30 years old. It starts and runs beautifully. I make a point of always running it for at least 20 minutes (usually much more) to minimise internal condensation etc.

Cheers, Graeme

[Cheechako]

Doing a repair, like Sailorchic did and rebuilding for "peace of mind" are two different things. If you are in the peace of mind camp, then you need to go beyond what SC did. Replace the injector pump etc. Then it gets more expensive.

[boatbod]

The GM series engines are generally very reliable. That said, I'd recommend a compression test; ideally you want all the cylinders fairly evenly matched and over 400psi. Once compression drops much below 400 they get hard to start particularly when cold.

I've also seen 3GM's suffer rod damage due to water backup from the muffler through the valves. Sometimes the bend it's slight enough that the engine still runs, but bad enough to fail a crush test and be a bear to start.

[grantmc]

Originally Posted by Cheechako

... It may be better if you do decide to rebuild to just replace it with a Beta at the cost of Yanmar parts...

On the face of it, this seems such good advice. But what about the fit and the other boat systems the engine needs?

I replaced a Yanmar with another brand of engine (not a Beta). Going down that route presents a number of extra problems. And costs. The engine bed needs rebuilding, engine mounts will need replacing (4 x $150). The front two mounts in my boat also needed some engineering due to the setup of the alternator. The fitting to the prop shaft will present itself as a problem. The different engine loom (dashboard) means a whole heap of wiring work. Probably any gauges you have need to be replaced (perhaps glassed in water ingress). If you’re going to replace the motor it’s pointless using the old transmission.

So now you have your motor sitting in the engine bay. But that’s only the start, it needs to have fuel. Is the old diesel tank going to supply nice clean diesel or is it pretty rusty? You’re spending thousands on a new engine, why not spend a few more hundred on a nice shiny fuel tank, plus replace the filter and all hoses. Let’s say $500
I would also replace the raw water intake, filter system and hoses with something more modern. Ideally that would also include the thru hull. (oh and what’s the point of only replacing one thru hull?) But another $300.
Back to the new Beta. The old throttle/gear selector (morse controls) for the Yanmar and cabling wont fit the Beta. Another $500 plus fitting.
Exhaust will need replacing as it’s all old. Plus different exhaust pressures between the two motors. Another $500.

So this was the point I was at with my boat. I had a running engine and transmission, with fuel, water, controls, etc. Wildly over budget and suddenly I realised the two motors rotated in opposite directions. My old Yanmar was setup for a left hand prop and the new motor was setup for a right hand. And when it comes to props you can spend as much as you want. A basic prop was $1,100. I could have spent 3 times that for a folding prop.

The fitting cost was about 9K. Even if I’d replaced like for like, the old services supplying the new engine still needed replacement.

And I’ll share one other fact. Before I did the replacement a couple of years prior I had had the old Yanmar rebuilt. But as many have discovered, new rings, pistons, sleeves, bearings, injector, etc etc doesn’t turn a 30+ year old motor into a new engine. It doesn’t correct the failures of previous owners repeatedly forgetting to turn the water on, or running the old girl at max revs for hours, or worse, only using the motor to get in and out of the marina and/or not having oil changes etc done appropriately.

And my story is the same story of most who repower a boat. And a postscript would be that if I made the decision to replace a motor today I would be looking very hard at an electric motor. And that’s because electric doesn’t need fuel, water or exhaust systems. Nor does it need oil changes or other expensive maintenance. And for 99% of people they’re perfect for getting in/out of the marina. For the 3-4 weeks a year when I travel away, I’d take a little cheap genset.

[captlloyd]

Originally Posted by grantmc

On the face of it, this seems such good advice. But what about the fit and the other boat systems the engine needs?

I replaced a Yanmar with another brand of engine (not a Beta). Going down that route presents a number of extra problems. And costs. The engine bed needs rebuilding, engine mounts will need replacing (4 x $150). The front two mounts in my boat also needed some engineering due to the setup of the alternator. The fitting to the prop shaft will present itself as a problem. The different engine loom (dashboard) means a whole heap of wiring work. Probably any gauges you have need to be replaced (perhaps glassed in water ingress). If you’re going to replace the motor it’s pointless using the old transmission.

So now you have your motor sitting in the engine bay. But that’s only the start, it needs to have fuel. Is the old diesel tank going to supply nice clean diesel or is it pretty rusty? You’re spending thousands on a new engine, why not spend a few more hundred on a nice shiny fuel tank, plus replace the filter and all hoses. Let’s say $500
I would also replace the raw water intake, filter system and hoses with something more modern. Ideally that would also include the thru hull. (oh and what’s the point of only replacing one thru hull?) But another $300.
Back to the new Beta. The old throttle/gear selector (morse controls) for the Yanmar and cabling wont fit the Beta. Another $500 plus fitting.
Exhaust will need replacing as it’s all old. Plus different exhaust pressures between the two motors. Another $500.

So this was the point I was at with my boat. I had a running engine and transmission, with fuel, water, controls, etc. Wildly over budget and suddenly I realised the two motors rotated in opposite directions. My old Yanmar was setup for a left hand prop and the new motor was setup for a right hand. And when it comes to props you can spend as much as you want. A basic prop was $1,100. I could have spent 3 times that for a folding prop.

The fitting cost was about 9K. Even if I’d replaced like for like, the old services supplying the new engine still needed replacement.

And I’ll share one other fact. Before I did the replacement a couple of years prior I had had the old Yanmar rebuilt. But as many have discovered, new rings, pistons, sleeves, bearings, injector, etc etc doesn’t turn a 30+ year old motor into a new engine. It doesn’t correct the failures of previous owners repeatedly forgetting to turn the water on, or running the old girl at max revs for hours, or worse, only using the motor to get in and out of the marina and/or not having oil changes etc done appropriately.

And my story is the same story of most who repower a boat. And a postscript would be that if I made the decision to replace a motor today I would be looking very hard at an electric motor. And that’s because electric doesn’t need fuel, water or exhaust systems. Nor does it need oil changes or other expensive maintenance. And for 99% of people they’re perfect for getting in/out of the marina. For the 3-4 weeks a year when I travel away, I’d take a little cheap genset.

A lot of the issues you bring up are going to be there exist either way. To me a persons ability to do most of their own work is a deciding factor,

[grantmc]

Originally Posted by captlloyd

A lot of the issues you bring up are going to be there exist either way. To me a person’s ability to do most of their own work is a deciding factor,

Popcorn I quite agree, but the OP made this statement at the end of their post:

Originally Posted by Tetra

..I've never owned a diesel-powered boat and I'm on the learning curve here. Thoughts?

So I was just pointing out that there’s much more needed to make a boat go under motor than just the motor itself. And I responded to the ‘replace the Yanmar with a Beta’ post as if that were easy peasy and heaps cheaper than a rebuilt or new Yanmar. From the OP’s statements I don’t think he/she appreciates the facts.
Also all that other stuff costs money, even if you can do it yourself, Yanmar don’t make their parts available free of charge. Quite the opposite, they charge seemingly ridiculously expensive prices for many parts, and the older the motor, it seems the more of a premium they add. Presumably their strategy is to incentivise sales of new motors.
Sailorchic, for instance, made a useful point about special Yanmar (read very expensive) tools being needed for some jobs.
And I also inferred from the OP that he/she is no more skilled at engineering/electrics etc than the average person you might meat on any street corner. I may be completely wrong, and certainly such skills can be learned, but the learning curve can be steep, and the mistakes make going up expensive.

[sailorchic34]

I should note that I could overhaul a 3gm for $1200, including new hoses, special tool (made not purchased). OK and lots of free Blonde labor. Even if I had rebuilt the injector pump and installed three new injectors, it would have been under $2000 for parts / service. A new engine is $8k-$10K and still needs to be installed.

Many with money will repower. Those with limited funds rebuild.

On the other hand a repower does increase the boats worth more then a rebuild.

[RedHerring]

I'd rather pay 10-15k extra, even 20k extra for a similar size/vintage boat that has been repowered in the last decade and has up to date rigging and sails. It'll cost less money and MUCH less time and frustration.

Unless you enjoy turning nuts while awkwardly suspended upside down in a dark dusty closet more than you enjoy sailing, of course.