Deciding between 380 gas (8.1 Horizon) and diesel (Cat 3126/350hp)

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Markw949

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Jul 14, 2020
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Hi - we are trying to decide whether to pay up a little ($20k more) for a 380 with diesels and a new installed bow thruster. Both are 2002 and roughly same hours 700. Would like to hear from any owners of 380's with diesels or gas and experiences - pros and cons. I know the diesels are heavier and boat may go slower, which isn't a big issue. Questions are differences in performance, maintenance, fuel costs etc.
Thanks
 
If you are anywhere besides a small lake, buy the diesel boat!

I nearly bought a 380 with Caterpillars when I balked and bought a 360 with 8.1 motors. If you plan on going places on your boat as opposed to just short hops to tiki bars or sandbars or just using it as a weekend waterfront condo, buy the diesel boat.

Did I mention I should have bought the diesel boat!!! :)
 
I looked into this a little bit when we were upgrading and came to the conclusion that it really breaks down like this, if you were going to run your boat 100 hours plus per year get the diesels. If you are not going to run 100+ hours get the gassers.

Our permanent mooring is in a town many travel to for vacation, we have the day boat, and of course obligations of life, we decided on the gas engines because we just do not travel enough to justify the diesel expense.

To me the above is what you need to calculate into your life, your goals for the boat, and where you Boat.
 
You don't mention where/how you boat, or the year boat you are considering. Generally though, a 380 is a great boat either way.

My favorite would be a 2003/2004 with either 8.1's or the 350 hp 3126's. With gas prices down, the case for the diesels makes for a longer payback period. If long distance cruising, diesels get you more range.

The bigger question is which boat is cleaner, better maintained and will take less to get brought up to your standards.
 
8.1's are likely the best engines that Mercury ever built. I absolutely love mine and have had zero issues with them in 400 personal hours of use (700 total
on engines) they push my 340 effortlessly no matter how heavily loaded, and I assume a 380 would be much the same. Heck they put these in 40+ foot SeaRay's too.

That all said, everything dtfeld mentioned are very important considerations as well. And my next boat will definitely have diesels no doubt about it. We do a lot of long distance cruising and fuel prices will return to normal eventually. Longevity with properly maintained diesels is also a factor. I'll probably sell the 340 before these engines get anywhere near a major rebuild (hopefully), but that is a consideration as diesels can go much longer than gassers if properly maintained.
 
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dtfeld said:
You don't mention where/how you boat, or the year boat you are considering. Generally though, a 380 is a great boat either way.

My favorite would be a 2003/2004 with either 8.1's or the 350 hp 3126's. With gas prices down, the case for the diesels makes for a longer payback period. If long distance cruising, diesels get you more range.

The bigger question is which boat is cleaner, better maintained and will take less to get brought up to your standards.
Click to expand...
 
Good point - home port is Warwick R.I. on Narragansett bay. We like to explore ports around the bay and of course Block Island, but also interested in venturing to the Vineyard, Nantucket and the Cape.

Both boats are in better than average shape, comparable in some areas one better than the other in some aspects. Pursuing both...

thanks for comments!
 
All else being equal...get the CAT's. There is a learning curve, but basic MX is pretty simple. Anodes, filters, oil, and trans fluids on schedule. All parts readily and affordable at the local CAT dealer.

If the 250 hour service (basically at the first oil change) was completed, then the next major tune up is at 2000 hrs (this is were the head rack and injectors are reset/timed). There is not a required 1000 hr service on CAT 3126's.

You'll be replacing the 8.1s before you do this service on the CAT.
 
You will retain that 20K investment with diesels when it's time to sell, but, when maintenance is due for real, that 20K will evaporate. Still, there's nothing like a helm saying "YESSIR" when it's time to do a maneuver.
I think it's more about how the boat feels about how you run it. I would never think of going the places I did in a 46 Post with my 370. It's 2 different events. They both have their moments, and for what we do with Beach House, gas is good. Especially now. Even my boat with the Cats is a "West Coast" runner. I'd take that one to Key West before the 370, except I would miss all the great improvements I've done to BH. My daily Dilemma. Pick one, go boating. See what the insurance difference is.
 
MonacoMike said:
I looked into this a little bit when we were upgrading and came to the conclusion that it really breaks down like this, if you were going to run your boat 100 hours plus per year get the diesels. If you are not going to run 100+ hours get the gassers.

Our permanent mooring is in a town many travel to for vacation, we have the day boat, and of course obligations of life, we decided on the gas engines because we just do not travel enough to justify the diesel expense.

To me the above is what you need to calculate into your life, your goals for the boat, and where you Boat.
Click to expand...

In another thread I was told I had to get over the fact that a 40+ foot cruiser looks better with an open array radar. I really like the cool factor.

I think there is a certain cool factor for having diesels. A lot of people I see that have diesels do not use their boat enough to warrant the expense. But they do get a very cool factor. LOL
 
380DA? No brainer - go diesel
Better market for resale
Better resale value
Better fuel economy
Safer to operate (no gasoline fumes)
Safer to be on (CO not the issue like it is for gasoline)
Diesel at 2200 RPM or Gas at 3800 RPM? Yup know that answer
Faster boat
Better handling boat for maneuvering
No ignition system
Usually easier and cheaper insurance (but insurance lately has been really screwed up)
And then that omnipotent diesel sound and feel - Ah Ah Ah.
Bragging rights and chicks love diesels....
and on and on......
 
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ttmott said:
380DA? No brainer - go diesel
Better market for resale
Better resale value
Better fuel economy
Safer to operate (no gasoline fumes)
Safer to be on (CO not the issue like it is for gasoline)
Diesel at 2200 RPM or Gas at 3800 RPM? Yup know that answer
Faster boat
Better handling boat for maneuvering
No ignition system
Usually easier and cheaper insurance (but insurance lately has been really screwed up)
And then that omnipotent diesel sound and feel - Ah Ah Ah.
Bragging rights and chicks love diesels....
and on and on......
Click to expand...

It’s only boat dollars! LOL
 
If you haven't yet decided on the diesels here is another reason. First my 8.1's are no longer made so if they go out your options are to rebuild the engine, buy a remanufactured engine or to repower to a newer model. Second issue is the cooling system, gas engines have a hybrid system where the the coolant for the engine block is closed but raw water flows through the manifold, the risers and out the exhaust. If your boat is in salt water, the manifolds, risers etc have to be replaced somewhere in the 6-10 yr region. I just replaced all of mine and it's roughly $1k per side or $2k per engine for parts only. It's probably $6-8k to have a dealer involved. I pretty sure the diesels are a closed water system and won't have this maintenance issue. Just a last comment that when I was looking, I saw a fair amount of older CAT diesels that had been rebuilt and I asked a CAT dealer who indicated there was a problem with a certain model. I don't know when Sea Ray changed but they went to Cummins on later models and from experience the Cummins is a better engine.
 
FWIW I had a 2001 420SC with Cat 3126TA for ten years, 2007-2017 and never had a moments trouble with them. Had Cat run the engine serial numbers to see if they were in the bad batch that had issues and nope. Never let us down a single time. Did 6500 miles over 13 months aboard doing the America’s Great Loop Cruise 2015-16 and loved every minute. Starboard engine developed a small water leak on the raw water pump so changed it out for new one and then continued our trip. Great Engine IMHO !
 
If you're doing any open water boating as it sounds like you will, Diesels all the way. A diesel boat handles rough seas much better maintaining steady power through the waves and fuel efficiency, safety and reliability all come with the package. You must maintain them properly with regular maintenance and they'll last forever.
 
Diesels!... you will recoup the extra investment at resell....just get a good price to start with
 
There were 2 problems with the 1994-1998 3116 and 3126 Caterpillar engines:

1. soft valve stems.....(occurred on both 3116TA and 3126TA engines) there the valve spring keeper would pop out of the recess on the valve stem. If the engine were at speed and producing power, this was a catastrophic failure that required an engine replacement, only those engines that failed at idle could be salvaged and rebuilt. Not all engines had the soft valves and there were no records of what valve when in what engine. This failure always happened @ 150 hours or less so if you are looking at engines with normal hours on them, you are well past the normal time of failure for the soft valve problem.

2. soft engine blocks.......(occurred only on 3126TA engines. -----NEVER on 3116's)----.

This defect occurred when the blocks were cast with improper metallurgy. The blocks wore prematurely allowing combustion gasses to escape by the piston resulting in excess blow-by and excessive oil consumption. Caterpillar either repaired of replaced all the engines they identified as having soft blocks. There was no record of what serial numbers had soft blocks until after the problem surfaced. Cat deemed that they had found all defective blocks by 1/1/05 and they no longer extend warranty coverage to repair or replace soft block engines after that date.

Therefore, there is no risk from these problems on Caterpillar 3116 engines. There is some risk, however minor, on 3126's. You can avoid the soft block risk by having the local Cat dealer do a blow-by test on any 3126 you are thinking of buying, This test will very quickly identify an engine that has crankcase gasses passing by the piston rings.

Caterpillar redesigned the 3126TA to make the 3126e and reduced the hp rating to 350hp and added electronic injector control. At the same time, they dropped the 3116 from the line mid-late 2002. All of the above problems were corrected in the 350hp 3126e, so there is no risk of soft valve stems or soft blocks with the 3126e which is seen in late 2002 or 2003 Sea Ray's using 350hp Cat engines.

The 3116 is a great engine and is very efficient and has an extremely low maintenance cost, lower than the 3126 because the 3116 after cooler is jacket cooled, where the 3126 is seawater cooled and needs more frequent aftercooler service.

Cummins makes good engines but their cooling system are a much higher maintenance design thanCaterpillar's


Frank
 
fwebster said:
There were 2 problems with the 1994-1998 3116 and 3126 Caterpillar engines:

1. soft valve stems.....(occurred on both 3116TA and 3126TA engines) there the valve spring keeper would pop out of the recess on the valve stem. If the engine were at speed and producing power, this was a catastrophic failure that required an engine replacement, only those engines that failed at idle could be salvaged and rebuilt. Not all engines had the soft valves and there were no records of what valve when in what engine. This failure always happened @ 150 hours or less so if you are looking at engines with normal hours on them, you are well past the normal time of failure for the soft valve problem.

2. soft engine blocks.......(occurred only on 3126TA engines. -----NEVER on 3116's)----.

This defect occurred when the blocks were cast with improper metallurgy. The blocks wore prematurely allowing combustion gasses to escape by the piston resulting in excess blow-by and excessive oil consumption. Caterpillar either repaired of replaced all the engines they identified as having soft blocks. There was no record of what serial numbers had soft blocks until after the problem surfaced. Cat deemed that they had found all defective blocks by 1/1/05 and they no longer extend warranty coverage to repair or replace soft block engines after that date.

Therefore, there is no risk from these problems on Caterpillar 3116 engines. There is some risk, however minor, on 3126's. You can avoid the soft block risk by having the local Cat dealer do a blow-by test on any 3126 you are thinking of buying, This test will very quickly identify an engine that has crankcase gasses passing by the piston rings.

Caterpillar redesigned the 3126TA to make the 3126e and reduced the hp rating to 350hp and added electronic injector control. At the same time, they dropped the 3116 from the line mid-late 2002. All of the above problems were corrected in the 350hp 3126e, so there is no risk of soft valve stems or soft blocks with the 3126e which is seen in late 2002 or 2003 Sea Ray's using 350hp Cat engines.

The 3116 is a great engine and is very efficient and has an extremely low maintenance cost, lower than the 3126 because the 3116 after cooler is jacket cooled, where the 3126 is seawater cooled and needs more frequent aftercooler service.

Cummins makes good engines but their cooling system are a much higher maintenance design thanCaterpillar's


Frank
Click to expand...
I believe there was also an issue with the cast stainless steel exhaust risers which were replaced on an as fail basis with bronze. I understand all have been replaced but always check.
Tom
 
Regardless, don't overlook the gears. The Hurth HSW800 V-drive gears have issues with the case strength at the countershaft bearings and have a sorid history of failure when that countershaft is used for forward propulsion as the Port gear does. So pay attention to the oil analysis on the gears.
 
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