Why do people replace diesel engines in a sailboat?

[Chotu]

Another thread got me to thinking. Why is it that people decide to re-power?

Assuming you have a working engine, a diesel engine, what is the point?

I see a lot of people pull out older engines and put in a brand new one. I’m thinking of ones like an old Perkins. Sure, they look old. And they probably don’t get as great fuel efficiency as the new ones. But why replace them if they are still running?

[geoffr]

We replaced our old yanmar 3GMD for the following reasons:

• GMD was raw water cooled and would cost more to overhaul than new
• YM30AE gave us more HP (29 vs 22)
• Quieter Engine
• Possibly better fuel economy (but I doubt it)

[john61ct]

Yes, I doubt many just doing it for the fun of it.

[svspirited]

Expense of overhaul and parts is a big driver. My Westerbeke had a full overhaul done to it after getting back flooded and blowing a piston. It was time for an overhaul anyway so the previous owner did it right and replaced everything that would typically wear out, new cylinder sleeves, injectors, water pump">raw water pump, heat exchangers, and a few other bits and the total bill was around $13,000. If it wasn't an insurance claim he would have put in a new engine for about $7,000 more. That same engine, circa 2002 vintage, is becoming increasingly expensive to buy parts for when you can actually find them. My next will likely be a Beta Marine, Kubota tractor engine with parts that you can actually purchase through tractor supply houses for a fraction of the cost of the "marine" grade parts and their support will tell you what the Kubota part numbers are, Westerbeke is all sneaky about saying what the equivalent Isuzu part is and charges 3-4 times the Isuzu cost. The only truly marine components for most diesel engines are the cooling and exhaust components.

[gmakhs]

If it works and you replace it is just waste of money.... From the other hand there people replacing perfect working diesel with doubtfull electric.....
My engine is a volvo.penta md5b dated 1984 if it break and I am in Greece I will refurbish it (cost around 600 euro ) if I am somewhere else in the world.maybe replace with outboard or electric whatever is cheaper .

[Sailmonkey]

I’ve seen replacement engines done by people with zero mechanical aptitude. Their thinking is if the engine is new they won’t need to worry about it.

I’ve also done replacements for engines that were otherwise OK, but lack of maintenance meant they were nearing the need for some major work. The age of these engines makes the cash expenditure for old/obsolete parts uneconomical.

[Teknishn]

I have been considering re-powering. Here's why: I have a Yanmar 1GM which is 6.5 HP. As a full time liveaboard and coastal cruiser I have kept up on the maintenance/repairs and the engine runs great. However, one of the complaints about the older Hunter 27's is that they were under-powered, which I've found to be true when fighting ICW currents, tidal flow, storms, etc. Have changed props as well to no real great effect. Great engine for getting to-and-from a dock, but not enough "umph" for cruising. I have room in my engine compartment to install a Yanmar 2GM20 (20 HP) with only minor modifications (lengthening the engine bed plates and moving my companionway steps forward 4.5-inches). No need to change the gearbox, electrical harness or engine controls. Additionally, parts for the 1GM have become harder to find. More pro's than con's in my case.

[rbk]

-lack of available parts
-cracked/warped head/block or other major component with no available replacements
-lack of qualified mechanics/failed rebuilds
-cost to rebuild with chance that rebuild goes bad (see above)
-cost for new is near equal with full rebuild
-neglected engine
-owner unable to do the work, farming out to qualified help $$$
-just plain worn out

But I agree that most are replaced prematurely for the wrong reasons.

[Squanderbucks]

I suppose for many of the same reasons they buy new to replace anything they own. I get the feeling from your post that you consider the engine an after thought and not something that is really something your care about other than when you may occasionally need it to get you through a specific spot.

Others may not feel quite the same as they may rely on theirs for a greater portion of their cruising and is of greater importance to their piece of mind.

As a side note as a member viewing and posting for a few years I see many posts that fall into two broad camps - those who are checklist and frequent maintenance people who try to do things by the book and the second camp that don't believe in working on or fixing anything until it quits running.

Diesels like anything wear out ( from use or disuse) and keeping them running is a matter of time and money assuming parts are available. If parts are available and you can do all the work yourself the rebuilds may be a good option. However when that is out of the experience, comfort level or just no desire to do the work then the labor to remove, rebuild and reinstall is a factor that must be weighed. sometimes replacement is the most cost effective.

[Captain Puget]

I replaced a Perkins that ran, but needed a rebuild of engine and transmission with a Beta. Reasoning:

- cost was about 10% more
- should last as long as I own the boat
- quieter
- larger alternator
- much easier to service myself
- warranties

[stormalong]

My reason was that the old one (Perkins 4-108) was leaking oil from the main seal due to blowby and it needed a rebuild. Rebuilds are a crapshoot. You will not know the actual cost until it is apart and finding the right rebuilder is tricky. Many mechanics claim skills they do not have. If you need a new crankshaft the rebuild cost could exceed the cost of a new engine. That engine is a 1940's design with some improvements. Also going into my decision was that my boat was underpowered.

After looking at a lot of engines I chose a marinized Kubota tractor engine. I made a list of all the things I didn't like about the Perkins and visited the marinizer at the factory. We discussed what I wanted and they gave me a price. They delivered what I wanted, sixteen years and over 4000 hours later I still have the boat and I am still happy with the decision.

[moseriw]

Originally Posted by Chotu

Another thread got me to thinking. Why is it that people decide to re-power?

Assuming you have a working engine, a diesel engine, what is the point?

I see a lot of people pull out older engines and put in a brand new one. I’m thinking of ones like an old Perkins. Sure, they look old. And they probably don’t get as great fuel efficiency as the new ones. But why replace them if they are still running?

SIMPLE: they are stupid.

Nothing can be better than an old tractor engine with big displacement and low rpms without scrap like turbos.

And it it worth to refurbish the engine even if it costs more than a new engine that works on 3000 rpm +++ instead of 1600 to 1800 rpm.

Assuming the same quality than the elder engines (which it is NOT) lifetime is cutted in half.

Nowadays the pray a lifetime of 8000 hrs. at max. Mine is a 1981 built and is as good as new. I asume 25.000 hrs. ++

The important thing! Change oil once a year in autumn - before the cold season.

[Ken Z]

rust.....cost of overhaul vs new.

[Sojourner]

Just had our 1991 perkins rebuilt instead of replaced. There are still issues, but working thru them. Simplicity is beauty when you are trying to be self reliant...

[Sail Away 3]

Originally Posted by Chotu

Another thread got me to thinking. Why is it that people decide to re-power?

Assuming you have a working engine, a diesel engine, what is the point?

I see a lot of people pull out older engines and put in a brand new one. I’m thinking of ones like an old Perkins. Sure, they look old. And they probably don’t get as great fuel efficiency as the new ones. But why replace them if they are still running?

In my case the cost to rebuild upper and lower end with associated gaskets with Volvo parts was close to the cost of a new Yanmar. I liked my Volvo but now with over 1000 hours on the new engine I like it just as much. Ken on Sail Away 3