Mainship Preferred Diesel- Catapillar or Yanmar?

Hello all,,,,

So as I am doing my research, I have seen a few listing where it is mentioned that "this Mainship 390 has the preferred Caterpillar 3126 Diesel"

Should I set that as a "got to have" on my list?

Jeff

jefndeb said:

Hello all,,,,

So as I am doing my research, I have seen a few listing where it is mentioned that "this Mainship 390 has the preferred Caterpillar 3126 Diesel"

Should I set that as a "got to have" on my list?

Jeff

Click to expand...

I can't help you in any way on this particular question... but when we get the answer to it, we can then move on to which is the best anchor...???

The single 390's were powered with Cat, Yanmar or Cummins.

I would take any of them in the right boat, but I am partial to Yanmar

I have a lot of personal experience with the Yanmar 6LY and know about the Cummins from reading about it here and on boatdiesel. Both are solid engines. I don't know much about the Cat but I suspect it is a solid engine as well.


As noted above, all of these engines would be very suitable and the choice should be more based on the condition of the boat and its price.


David

I have read criticism of Cat 3116 and 3126. You could try online searching.

I'm not much of a fan of either Cat or Yanmar, many boats where I am have John Deere, either the 6068 6.8L or the 6090 9.0L. Deere dealers are everywhere.

Cummins first, then Yanmar, don't touch Cat, the Cats have poor resale.

jefndeb said:

So as I am doing my research, I have seen a few listing where it is mentioned that "this Mainship 390 has the preferred Caterpillar 3126 Diesel"

Should I set that as a "got to have" on my list?

Click to expand...

I would suspect this could be a broker-induced preference... where whatever engine in the boat a broker is about to list suddenly becomes "the preferred" (whatever).

-Chris

Thanks much...so as far as hours go,..... what would be considered low. medium or high...or is that another question that is really objectionable....
Thanks

The early cats of 3116 3126 vintage had serious head and valve issues. They were usually replaced or rebuilt by Cat under warranty and owners were happy with them afterwards. Unfortunate in the boat world reputation once soiled never recovers.

In answer to the OP question Cummins would be my hands down choice.

Magic has 3116’s. We have logged 4,915 hours without a single repair. They are fuel efficient and very smooth running. The problematical engines had blocks built in France and they failed in the first 500 hours. The serial number will tell where the block was built. BTW, CAT repaired or replaced the defective engines. If you like the boat I would not hesitate.

hmason said:

Magic has 3116’s. We have logged 4,915 hours without a single repair. They are fuel efficient and very smooth running. The problematical engines had blocks built in France and they failed in the first 500 hours. The serial number will tell where the block was built. BTW, CAT repaired or replaced the defective engines. If you like the boat I would not hesitate.

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The 3116 and 3216 should run the Cat recommended oil, for a reason I don't recall. In any case, a Cat or Cummins is likely to run quite a bit longer than the higher turning, much lighter weight Yanmar.

Engine condition and potential longevity are not determined by engine hours alone! Little used (or not used) can be worse than having higher hours. Maintenance, or the lack thereof, can greatly influence costs (and problems) for the new owner. "Marine age" (more of a concern for boats used in salt water) often is much more of an issue than engine hours. I know another NT owner who has well over 9000 hours on his Cummins, and it is still running well and showing no signs of impending issues. However, the engine has been well maintained!
Look for detailed maintenance records. At least those can give an idea of what was done and how often. Beware of boats with no records. I always wonder what they may be trying to hide and, how did they keep track of what needed to be done and when without records??? My memory is pretty good, but no where near that good!
I personally like Cummins for many of the reasons stated above, and because parts are readily available, they have a good reputation (not perfect however), and most mechanics are comfortable working on them.

I once worked a short while (as a temp) for an ME with a excellent pedigree (an early job after college was for the big shots at Alamogordo, NM in the late 1940's), whose resume included engine development at Caterpillar. Never forgot one offhand comment while testing a small Mitsubishi motor, "absolutely nobody builds better engines than Caterpillar".

Before purchasing ensure that replacement parts are available for the engine make in question. If I had followed that advice, I would never have purchased a boat with VOLVO engines.

jefndeb said:

Hello all,,,,

So as I am doing my research, I have seen a few listing where it is mentioned that "this Mainship 390 has the preferred Caterpillar 3126 Diesel"

Should I set that as a "got to have" on my list?

Jeff

Click to expand...

Jeff, that is just broker speak.

He is not suggesting that the Cat is preferred for that specific boat, or that the builder prefers to put Cats in them (which they may or may not do). He is suggesting that people prefer Cats generally.

Which of course is just so much bunkum. People have engine preferences across the spectrum based on many variations of needs and wants.

The original owners of Sonas (hull #1) ordered two Luggers (LP668Ts), which is a very unusual set up. They obviously had very specific to them considerations. Hull #2, Nagari, has twin CAT 3126B Engines.

So simply ignore the use of "preferred."

As a 15 year Caterpillar employee...I can say I've never been in a meeting where we decided to build a product that wasn't the absolute best in the market. I've been involved in several competitor tear downs and every time we identified something on the other machine that would cost less...we chose to keep our "over" built part. From the number of hose clips to the thickness of the sheet metal in the engine enclosures and everything in between. Have we missed in the past...yes. But you'll not find a better warranty or better dealer network worldwide for a Marine engine.

https://www.cat.com/en_US/support/protect-your-investment.html

Are the other manufacturers listed above good choices? Yes. Are they the cheapest...maybe. Are they the best...probably not.

Carry on,

Sidney
(I'm not in sales nor do I work for a dealer or directly in the Marine Division. I am however invested heavily in CAT stock.) Thanks.

jefndeb said:

Should I set that as a "got to have" on my list?

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I wouldn't! Since 1995 I have had Perkins, Cummins, Detroits, Cats & Yanmars. My favorite has been Cummins. They are easier for an owner to maintain. (IMHO) While searching about 5 years ago for my favorite boat (OA 42 Sedan) with specific attributes, (hard top, side by side births in the guest cabin, no down helm, etc,) the only one I could find after 3&1/2years of looking had Yanmars! Knowing absolutely nothing about Yanmars, I turned to an old broker/captain friend of mine for his advice. He said "Walt, I know you love Cummins but I believe the Yanmar is a better engine!" I bought the boat & I absolutely love the Yanmars!

Conclusion: If you've found the exact boat of your dreams, research the engines and go for it! All engines have had some bad press, justified or not.

For the Mainship, I rank the engines in the following:
Yanmar
Cummins
Cat

As a disclaimer, I've only owned Yanmar, but they are well made, bullet proof and easy to maintain. And I have a top notch dealer/distributer locally whose generous with good info as well as parts, etc.

I have a LOT of friends with the Cummins in their Mainships, and I could rank it as an equal to the Yanmar. I think you could flip a coin and be happy with either.

I've had friends with Cats, but in different boats, and no big issues there either..... and certainly not a distant third, but very close to the others.

Would agree with the comments that it probably makes more of a difference with the way the engine has been maintained, not the brand.

However, Volvo does seem to have issues. I've had a few with issues and friends with issues and occasionally had some friends that were grounded for months because they couldn't get parts (and they were expensive).

"Are the other manufacturers listed above good choices? Yes. Are they the cheapest...maybe. Are they the best...probably not."

The lowest cost of new Volvo engines for an OEM, is how they get stuck in boats, ,

Thank you all for the advice. I think we are leaning towards an early model Mainship 400 with a single Yanmar/Cat...We looked at a 1998 350/390 last weekend and I was surprised to see it aluminum railing which had corrosion, gelcoat was still in good shape though.... This would bug me pretty bad..Seems the 400 has Stainless steal which would be the norm...I am learning still but the wife is on-board as well!!!

There was a stretch of time when Cat was having difficulties with the 3116's. Engines grenading between 500-1000 hours. It didn't impact all model years.

If you have a Cat 3116 that is over 1,000 hours, you're more than likely fine.

Caterpillar 3116/3126 Soft French Block Issues

jefndeb said:

Hello all,,,,

So as I am doing my research, I have seen a few listing where it is mentioned that "this Mainship 390 has the preferred Caterpillar 3126 Diesel"

Should I set that as a "got to have" on my list?

Jeff

Click to expand...

I think this is mostly a creative seller's 'marketing hook', and it's B.S. If anything, this probably stems from all of the trouble Mainship had with the infamous Caterpillar "soft block" issues that --began-- with the 3116, and the mistaken notion that this was somehow 'fixed' with the 3126. It was not. While SOME 3126 engines were built with the newer blocks, most were not.

Background: At the beginning, most (if not all) of the Mainship 350/390 singles had Cat 3116 (and later, 3126) engines. The story Jim Krueger of Mainship told me was that there were a large number of 3116/3126 engine blocks manufactured in France that were incorrectly alloyed and hence the cast iron was 'soft', which was a particularly big problem in marine applications due to the usage profile being very different from that of a truck or construction vehicle. These engines were 'failing reliably' within the first couple thousand hours.

After a long fight, finally Caterpillar approved a 'silent' warranty campaign where these blocks could be replaced by Caterpillar. In the end, the Caterpillar 3116/3126 engines gained a well deserved reputation for early-life failures. An unknown number of these engine block were replaced, leaving an unknown number of them still out there.

If you go to David Pascoe's website, you will find that this was a well-known issue by 1999. After 2002, the 'Caterpillar Problem' had gotten so bad that AFAIK, there were no more 390s getting Caterpillar engines and the only choices were Yanmar or Cummins. I myself have never heard of a 2002 or newer model that was delivered with a Caterpillar.


Also, if you want more details go here: https://boatdiesel.com/Forums/Powertrain/Caterpillar-3126-Series/ForumSearch/soft-block.cfm


Over the last many years since I looked into this issue and spoke with Krueger directly, I have heard many Caterpillar afficionados claim that "all of these blocks were eventually replaced under warranty". I know this is not true because when I looked at six different MS390s in 2012-2013, I found two "low hours" boats with Cats that had the french-block engine stamping designation.

Bottom line, unless a seller can PROVE that a Cat 3116/3126 does NOT have a French block, then you should steer clear.

In my experience, the only 'preferred' engines for MS350/390 single-engine models have been the Yanmars and the Cummins. If you can find a broker who will pull a "sold boats" report from Yachtworld, you will find (as I did) that there is generally a 15-20% price 'break' for MS390s with Caterpillar engines versus the 'preferred' Yanmar and Cummins examples.

That doesn't mean you should automatically walk away from a Cat 3126, but you should expect to pay less and you need to be very careful doing your research to make sure you are not getting a soft French block.

The biggest problem (for me) was that Caterpillar never PUBLICLY acknowledged the problem. This leaves buyers in the used market not really knowing whether the boat they are buying is a 'lemon' or not.

So, any Mainship 350/390 with any Cat 3116/3126 is definitely a BUYER BEWARE situation.

You will learn much more on this topic if you do a google search on 'caterpillar 3126 french block soft'.

As you can see everyone has an option, as one suggested, search, I liked boatdiesel dot com for this, become a member and just read the archives, with enough reading you can see trends etc. For Cummins I would also look at Tony Athens Seaborn website, he has alot of good articles on the subject, pay special attention to "marine age".
Read read and read some more and the picture will clear up for you. Good luck in your search!

As I understand it, VOLVO has cornered the market by allowing the boat builders to not pay for the engines until the boat is sold. You would think with all the new VOLVO powered boat, they would have a chain of dedicated VOLVO dealers, but this is not the case.

Stainless steel rails on MS390

jefndeb said:

...looked at a 1998 350/390 last weekend and I was surprised to see it aluminum railing...Seems the 400 has Stainless steal which would be the norm...

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Don't be confused. Many 400/40/430 have aluminum rails. Mainship used the aluminum railings on --ALL-- of the models built through mid-2002.

For the 2003 model year, all Mainships (including the 390) were upgraded to stainless steel railings.

The stainless steel railings on our 2003 390 are some of the nicest, beefyest and well built railings I have seen on any boat. They are made of a fatter 1-1/4 inch stainless vs. the 1" rails used on virtually every other boat in this class. The stancion bases are massive and at least twice as thick as standard 'trawler class' construction.

The aluminum railings on the 2002-and-older Mainships were a simple (and in many ways, sensible) cost trade-off. They were excellent at doing their job (and also 'beefy' at 1-1/4"), but they did require regular maintenence (waxing).

In the end, there were a long list of things that Mainship 'fixed' for the 2003 model year, including the railings, that caused us to eliminate the older models from consideration.

We found that this is reflected in the price, as the 2003 and newer Mainships seem to have retained more value than the older models.

My personal preference would be Cummins.

Let me offer a few more of my "cents" on this topic:


Here is a quote from a post by Tony Athens made on his sbmar.com forum a few days ago:


"The 6LYA is a very good engine, and IMO, is as good as a 370 Diamond in many ways, but it is not forgiving, nor can it be “fixed” cost effectively when it’s abused to where it needs a rebuild."


The 6LYA reference is to the American assembled Yanmar 6LYA 370 hp engine offered in many Mainship 390s, 34Ts and 40s. The 370 Diamond refers to the Cummins 6BTA 370 hp engine. I can't really explain his comment about The Yanmar not being forgiving and can't be fixed effectively. Maybe the the former is due to its light weight that reacts quickly to loss of R/W flow and the latter is due to parts prices. It does have replaceable cylinder liners.


Here are some objective differences that I know of personally:


Pluses for the Yanmar: Compact and relatively light, better designed after cooler- doesn't corrode as much as the Cummins, Johnson R/W pump is solid.


Negatives for the Yanmar: Aluminum exhaust manifold- requires special antifreeze but no other problems if you use it, single 1/2" alternator belt- limits use of HO alternators.


Pluses for the Cummins: More cubes than the Yanmar, heavy bottom end that rarely wears out or fails, serpentine belt allows higher alternator power (although idler has been problematic), cast iron exhaust manifold.


Negatives for the Cummins: Poorly designed after cooler leads to excessive corrosion which requires regular servicing, Sherwood R/W pump fails early- Seaboard has a better one available, replacing R/W pump often requires raising the engine, heavier and taller than the Yanmar.


I have nothing to add about the Cat.


David

Urban legends (again)?

Delfin said:

...= run quite a bit longer than the higher turning, much lighter weight Yanmar.

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Never heard this before, so I checked...and it's apparently an urban myth (what we used to call an 'old wives' tale).

1) The 5.1 litre Yanmar 370hp 6LYA in our MS390 weighs 1,168 lbs. The 5.9 litre Cummins 370hp 6BTA "Diamond" engines in our 4788 weigh 1,140lbs.


So, since the Yanmar is actually a smaller displacement engine than the Cummins, and the Yanmar is actually --heavier-- therefore one should presume beefier construction on a "lbs-per-displacement" basis. These engines are virtually identical (with a slight edge to Yanmar) on a 'lbs-per-horsepower' basis. In any case, I don't think either of these is valid basis to trash an engine for 'theoretical longevity', but in any case, the notion of a "much lighter weight" Yanmar" is totally false.

2) The 5.1 litre 6LYA is rated for 370hp at 3,3000, the 5.9 litre Cummins is rated for 370hp at 3,000 rpm. Two takeaways here -- first, the rpm difference is nearly meaningless. Second, as we've learned over the last 40 years, smaller displacement engines running at faster RPMs to achieve similar horsepower result in --greater-- reliability, because they develop less torque for any given horsepower. This reduces the load on bearings, piston rings and everything else in the engine. Combine this with the incredible advances in engine oils, metal alloys and precision machining and it's easy to see why new, faster-spinning engines are more reliable, not less.

Sorry...I don't mean to contradict so flatly, but if we are going to trash a particular brand of engine, I expect we all want to get our facts straight first.

I own both the Yanmar and the Cummins. Both great engines. Slightly less troubles with the Yanmar...

Again, Yanmar myths?

djmarchand said:

"...Maybe the the former is due to its light weight that reacts quickly to loss of R/W flow and the latter is due to parts prices. It does have replaceable cylinder liners."


David

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I presently own both the Yanmar 6LYA-STP and the Cummins 6BTA "Diamond". The Yanmar is 5.1 litres and weighs 1,169lbs. The Cummins is 5.9 litres and weighs 1,140 lbs. These are from the factory spec sheets. Yanmar specifies the weight as "dry", the Cummins sheet doesn't say wet or dry. Either way, the Yanmar is HEAVIER.



I would love to know where this myth about the Yanmar engines being 'light' came from???.


Tony Athens (whom I have hired in the past and worked with personally) is truly a wonderful resource, but he is a Cummins factory guy (even though he no longer works for Cummins). Certainly he is knowledgable across all brands, but I don't think his opinions on Yanmar serviceability are the definitive last word.