hotfoot5

We are looking to upgrade to a smaller twin diesel sportfish or express in the near future and I am learning and researching different aspects of these boats. I keep reading information on diesel engines and what the expected maintenance costs are, and I am totally blown away at the figures that I see. Are people really paying 10-15 for engine maintenance? I understand that when turbos etc go bad, they can be pricey to repair, but not 15k.

I have owned and ran diesel trucks and equipment for years and thousands of hours, and other than the odd expensive repair, they are nothing like what I am seeing quoted for marine diesel engine repairs.

I understand that the labor costs can be higher, but why is the 1000 hour service so crazy, nothing on the heavy equipment or diesel trucks is anywhere near as in depth or expensive.

Besides the typical " Break Out Another Thousand" answer, why is the maintenance on these engines so much more in depth?

Pineapple Express

You need to get specific about the exact models of engines you're looking at. An 800hp MAN is gonna be different that a 12V71 Detroit or 350hp CAT or Cummins

hotfoot5

I should have specified. Were looking at boats 36-42 feet with Cat 3208s, 3126s, smaller Cummins and Yanmars and possibly Detroits..

mystery

1,000 hour services can easily be $10k per engine depending on the engine

If you do everything yourself you will save

I spent nearly $1,000-1,500 per year in just parts for my diesels for normal filters and fluids.

hotfoot5

Thanks for the reply. This is exactly what I am talking about, as I want to know why the cost is 10k for maintainence a year on a marine diesel engine. What makes it so expensive? On my diesel pickup truck, I bet Ive spent $400 this year on fluids and filters and the engine has over 4000 hours on it with all recommended services performed. Never, have I spent anywhere near that on a diesel engine, and outside of premium labor, I dont know why there is such a huge cost to maintain these engines.

mystery

read the maintenance schedule.

Esuomm1

10-15 is for the guy who tells the mechanic do whatever you need to and then the mechanic does half of what he says and charges 2x as much.

Of course it can depend on hours but for the avg 100/200 hour a yr boater, nothing close to that cost.

Pineapple Express

Also, think about the duty cycle of these engines. The Cummins in your 3500 has a way easier duty cycle compared to the same engine in a boat where you might be operating at 65% load for extended periods of time

Aliboy

It really is very engine dependent, and what you can do yourself. I reengined my sporty with a pair of 5.9l 6 cyl electronic Ivecos 16 years and 5000 hrs ago. I do my own wrench turning and haven't spent $1000 on either engine outside oil, filters, anodes, and impellers. i'm about to replace engine mounts on both engines and pull the coolers for another clean. May get the injectors recalibrated as well. A few gaskets and fluids but my own labor. Probably going to cost a bit under $1500 per engine. Oil changes are 600hrs, but i do them at 500 or more often sometimes. Oil, filters, anodes, impellers come to about $400 per side and takes me about 2 hours per engine to do the changes. Coolant change every few years but it isn't a big cost at that frequency. Total per year with my own labour including all routine maintenance less than $1000 per year. At some point i will doubtless have to look at turbo rebuilds, pump rebuilds, and some new senders etc but the blocks appear to be good for 10,000 to 15,000 hrs at my rating so by rebuild time i estimate the cost might be around $1500 per year plus my time, but i am only talking about averaging less than a couple of days per of wrench turning. I couldn't power the boat with outboards at the same cost per hour, let alone fuel costs.

I've run and maintained quite a lot of diesel boats with 3208's, 6BT's, 6LP's, D3's, D6's, D254's, 12V71's, and KAD32's. The above Iveco example is as good as i think it gets for costs. The others all varied and the way they are installed and run can make a huge difference in your costs. Learning your own basic maintenance is not difficult and will save a lot of money. Calling a mechanic everytime something small needs checking gets expensive. One really key thing if using a mechanic is to get someone knowledgeable to check how good maintenance access is. A simple 30 min job can take a day if access is poor. i've worked on boats where a 1000hr service was faster if you pulled the engines and reinstalled them rather than trying to work on them in place. I've seen installations where some maintenance access was so bsd that certain things didn't get maintained until they broke.

Gali

This. Normal annual maintenance for diesels in the mid 30's is nowhere near 10-15k. There are too many people here who probably tell their mechanics do everything you need to do and they do everything known to man, and charge extravagantly for it. You're not replacing turbos, after coolers, impellers, etc every year this is not anywhere near a normal replacement item. THT likes to poop on diesels and put outboards on a pedestal. And your "1000 hour service" is nothing crazy. For the average boater its a 10-15 year interval to hit 1000 hours. You'll probably touch these items sooner. Cleaning out the aftercoolers, potential raw water pump rebuild? (For reference SBMAR sells their "upgraded" pump for $750 brand new) Valve adjustment? General hoses, filters, etc... If you check out the guys at SBMAR you can do alot of these things proactively with a couple of hours of your own labor. Rather than all in one big dump. If anyone is paying 15k per year in annual maintenance cost in a mid 30's twin diesel they are getting ripped off. Must be nice to have that much and not care to toss it away

fireisland1

In another thread an owner paid almost $2000.00 for a Cummins electric fuel pump { part only } . I buy them for $320.00. Diesel can be another word for bend over. You must shop. Either learn to do basic maintenance or pay for someone to teach you. Average annual maintenance for my Cummins is about $500.00 . I travel about 2000 miles a year. I do all work myself.

mystery

I guess if you have a Volvo you are screwed. Not much shopping around you can do.

HGR

I would recommend looking in to a boat that has a common engine with easy access to parts and service to keep the costs down. We have 2x 6BT's in ours and they're super cheap to maintain and easy to work on. Being proactive helps as well because you can schedule it and generally see other maintenance items while you're in there that are much easier to fix at the marina then at sea, hoses and clamps are a good example. Get a copy of the factory maintenance program and apply that to the hours you think you will put on the boat in a basic excel sheet, it's a good way to compare brand to brand maintenance regimes.

mymojo

Have had diesels for the last 20 years. (1) Yanmar 6LP, a pair of Cat 3116's, pair of Volvo TAMD 41A's and now for the last 9 years a Volvo KAMD42p. Average recreational boat 60-100 hours a season in the NE. Never in any of those years have I spent anywhere close to 10k. I do basic maintenance myself, fluids, impellors. Most expensive year for me was injector service for 12 injectors @ $125 a piece IIRC and a pair of heat exchangers for the TAMD 41's which were hard to source for the then 2o year old Volvos and $2k apiece to buy and install. So for that one season I was into the boat for about $6k plus normal expenses. My current boat has a single Volvo KAMD42 and I run maybe $1k/year if that but know that there will be some expenses coming down the road since the engine now is 25 years old.

offshorebri

I have had diesels for 30 years now. NOT 1 single year did I spend 10,000 for maintenance. Actually much less than half of that. Most years it was a few hundred for oil, and zincs...

I have had....
Detroit 8.2
yanmar 4LHA
volvo tamd41
yanmar 6lp
volvo tamp75

my very good friend had
cat 3116, 2 sets in 30 years he also never spent 10 grand on maintenance

rwsrws

I have Yanmar 6LP x2 in a repower I did in 2006.

These are NOT common rail

These have ZERO electronic circuit boards

Do all normal PROACTIVE maintenance myself

Flush engines after every use.

Other than normal maintenance the only items that have failed is one starter solenoid and one hose (that I should have replaced)

15 years of use

Overall for me it's either diesel inboards or gas outboards - nothing in between makes any real sense

Have Northern Lights diesel genny

For me diesel safety & reliabiliy is everything

RWS

Slimshady04

All the above responses are pretty accurate and they come from some knowledgeable owners. Salt water was not mentioned though.
Like you I also have lots of heavy equipment and diesel boats. The salt water running thru the motor and some salt in the air are what increase maintenance. All the heat exchangers, air coolers ect. They need attention periodically because of the salt and minerals in the water. This is not an issue in your dozer or excavator unless she went for a swim!!😂
Also a small oil leak on 5000hr excavator is acceptable, that's not ok on $3million sportfish.

rwsrws

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All very good and valid points

However some of these matters CAN be mitigated:

a fresh water flushing system used after each use can reduce the cooler issue.

Coolers will be found on both gas and diesel inboards that flush makes a big difference

RE: salt air/salt water spray - Diesels of the vintage prior to the addition of electronic injectors will have less electronics than a gas engine.

This was one of the factors in my own making the jump from the 454 gas Crusaders to the Yanmar diesels

Hope all of this helps

RWS

LI32

A 36-42' boat with 300-400 hp, which is what you are looking for and sounds like a big cruiser like a SeaRay, will be very expensive to keep running as it will be seriously under powered and thus overloaded. Most properly powered 36' boats would be running 450-600 hp per engine and at 42' you are looking at 650-1,000 hp per side.
With the engines you have identified, you are looking at well used boats, so often times the 5 year (1,000 hour) service will include lots of things that are both labor intensive and pricey: after cooler servicing, hose and belt replacements, seawater pump rebuild or replacement, thermostats, heat exchanger core cleaning, fuel system timing and valve lash adjusting, plus the usual oil, air and fuel filters, zincs and replacing anything else that is worn.
If you have a CAT/Cummins/MAN mechanic do the work you are looking at 2 full days for a team of two or about 40 hours of billed labor ($175/hr by me) plus another $5-7,000 in parts, materials an subcontract work (aftercooler cleaning and water pump rebuilds).
The 2,000 hour service on my 38 Cabo with CAT C12's was $12,700, which included replacing both water pumps, all the hoses and everything else with two days of labor for one tech and three days for the second tech.
As far as regular yearly maintenance like oil changes, winterization and zincs, if you can do them yourself, it is maybe $1,000 in parts - having it done is more like $2,500.

Nomans

For 2020, I spent approximately $2,500 to have a pair of Cummins QSB 6.7 engines, Twin Disc gears, and a Northern Lights generator serviced by a factory-certified dealer tech. That includes several hundred dollars to winterize and all the zincs, oil, and filters. The most I have ever spent annually was about $4,000 when the service also included taking apart and cleaning the aftercoolers and heat exchangers. I have also spent less than $500/year in the past by changing impellers, zincs, and fuel filters myself.

Over an 18 year period of owning twin Diesel express boats, I have never come close to $5,000 let alone $10,000 on engine maintenance. That's running about 200-250 hours per year most years and about 300 a few years when I made long trips don the coast. I do not run my engines over 65-70% load at cruise and have a fresh water flush system that I use whenever the boat will sit for more than a day or two. I have never had to replace a major component. In my experience, Cummins makes excellent, reliable engines that will treat you well if you treat them well.

There are many other expenses just as big or bigger than maintenance for which you need to be prepared. My insurance costs more than the engine maintenance for example. Bottom painting is over $1,000 per year. I send my props out to be scanned and tuned every couple of years, which is around $700-$800. Last summer I had to spend $300 on a new fish box macerator pump and $200 on a new impeller for the air conditioning salt water pump. Just be sure your budget can tolerate all these things, which tend to go up substantially as you move up in size and complexity of systems. And then there's fuel....