*THE HULL TRUTH is the world's largest FREE network for the discussion of Boating & Fishing. Whether you're researching a new boat, or are a seasoned Captain, you'll find The Hull Truth Boating & Fishing Message Forum contains a wealth of information from Boaters and Sportfishermen around the world.
Welcome to the updated THT!
If you are having trouble signing in, please email feedback@thehulltruth.com with your username and we will help you. We thank you for your patience as we help you access the new site!
Random Quote: To those who know, no explaination is necessary. To those who don't, none is sufficient!
My buddy that bought a 28' Proline salvage boat from Hurricane Katrina has removed the 6 cylinder Yanmar diesel (300HP) and planned on rebuilding the engine. He found that the engine needs a lot of stuff including new valves which are going to cost about $6K. He's found that you can only buy Yanmar parts through Yanmar and everything is super expensive. Gasket kit for intakes and head are $1K, starter is over $1K, alternator is $1,100. So he is running into much more money for the rebuild than he expected.
He can buy a new 7 liter 350HP+ gas engine complete with warranty for about $8,500, and asked my opinion on whether he should rebuild the diesel or buy the gas engine.
I told him if it were me I would buy the gas engine for the following reasons:
-The gas engine weighs about 900-1000lbs less than diesel which will help offset the better mileage he would get with the diesel.
-The gas engine will come with a full warranty and is brand new, not a rebuild as he will have with the diesel.
-I think most people would prefer the higher horsepower gas engine over the diesel that came with the boat. The diesel engine had to be an expensive option so I'm wondering how the gas engine will effect resale value.
-Gas is easier to find than diesel fuel, it costs less (at least now), not as dirty and you don't have to worry about changing filters as often.
-He can sell the diesel engine to help offset the cost of the new gas engine.
He plans on rack storing the boat and using it a couple times per month as he is keeping it on Lake Erie but he lives in Kentucky so he's not going to be putting many hours on the boat.
Opinions needed, should he rebuild the diesel...if so, why? He should buy the new gas engine...if so, why?
Russ
I'm looking for opinions on whether or not he should rebuild
I think the answer will present itself if you look up the fuel consumtion for both engines.
Use the numbers to figure an approximate average day of use, translate that into an average season of use etc. Then factor in the resale value of a diesel boat over gas.
MHO is you will end up rebuilding the diesel. There's a lot more to the diesel equasion than fuel cost and lower consumption. Longevity of the engine for one thing. Typical numbers of 20000hrs before major work vs 2000 on gas on average. There's a good reason gas engines are less expensive. Crunch the numbers... It's worth the exercise.
Location: Los Angeles, FL.or Georgia, depends. In Fl now.
Posts: 5,979
RE: Help! Rebuild diesel or buy new gas engine.
Quote:
RussH - 5/2/2006 9:19 PM
My buddy that bought a 28' Proline salvage boat from Hurricane Katrina has removed the 6 cylinder Yanmar diesel (300HP) and planned on rebuilding the engine. He found that the engine needs a lot of stuff including new valves which are going to cost about $6K. He's found that you can only buy Yanmar parts through Yanmar and everything is super expensive. Gasket kit for intakes and head are $1K, starter is over $1K, alternator is $1,100. So he is running into much more money for the rebuild than he expected.
He can buy a new 7 liter 350HP+ gas engine complete with warranty for about $8,500, and asked my opinion on whether he should rebuild the diesel or buy the gas engine.
I told him if it were me I would buy the gas engine for the following reasons:
-The gas engine weighs about 900-1000lbs less than diesel which will help offset the better mileage he would get with the diesel.
-The gas engine will come with a full warranty and is brand new, not a rebuild as he will have with the diesel.
-I think most people would prefer the higher horsepower gas engine over the diesel that came with the boat. The diesel engine had to be an expensive option so I'm wondering how the gas engine will effect resale value.
-Gas is easier to find than diesel fuel, it costs less (at least now), not as dirty and you don't have to worry about changing filters as often.
-He can sell the diesel engine to help offset the cost of the new gas engine.
He plans on rack storing the boat and using it a couple times per month as he is keeping it on Lake Erie but he lives in Kentucky so he's not going to be putting many hours on the boat.
Opinions needed, should he rebuild the diesel...if so, why? He should buy the new gas engine...if so, why?
Russ
I'm looking for opinions on whether or not he should rebuild
EVERYTHING in the engine room has to come out or at least be checked out for its ignition-protected status. NOTHING in a diesel boat is required to be ignition-protected. This is NOT TRUE for a gas powered boat.
I wouldn't do it. I'd find a different diesel - perhaps a running take-out from a similar boat - but would not go to gas power.
Did the engine go under water? Yanmar used to have an exchange program to get a factory rebuilt engine.
If the costs for the rebuild vs. a new gas engine are the same then I would recommend going with the rebuild of the diesel for the following reasons:
1. The boat will have a much higher resale value with the diesel.
2. There will be other costs associated with the diesel to gas conversion making the gas conversion more money in the end.
3. I seriously doubt a 300 hp yanmar weighs 1,000 more than the gas, the gas won't have the torque of the diesel, and the gas engine will probably not perform as well as the diesel in the end.
__________________ Michael Dunlavy
Saunders Yachtworks
-----
24 Topaz, 15' Stauter
Yes the boat was underwater for 1-2 weeks. The engine he is interested in buying is a marine engine, it already has all of the proper ignition protected equipment mounted on it for a marine application.
Just about everything has been removed from the boat including all wiring, all instruments, engine, fuel tank, etc. I don't understand what would be so difficult in replacing the diesel for the gas. The engine mounts will need to be changed but all the fuel lines and everything has already been removed.
He's been in touch with Yanmar getting prices on replacement parts but I'll ask him if they still offer an exchange.
I'll suggest he contacts Proline about fuel consumption differences. I agree the difference in longevity his a big consideration for keeping the diesel but I doubt if he will put more than 50 hours a year on the boat.
Based on what Yanmar told him the diesel weighs and what he knows the replacement gas engine would weigh is between 900-1000lbs. Wouldn't there be a value for the existing Yanmar engine he is considering swapping out?
I'm shocked that so far everyone has voted for the diesel, I didn't expect that.
The gas engine will be lighter, higher hp, cheaper to buy, and most likely cheaper to operate when you factor in the costs of oil, filters, fuel, and parts. I'm not sure you can convince me that the longevity of the diesel will offset the costs. Also, spending a bunch more on a diesel to get back a little on resale makes no economic sense.
That said.....
The diesel is safer, has more appeal to many boat owners, can make your boat move faster when you sell, there wouldn't be a major swap, and boats with gas engines have everything ignition protected as mentioned above. That last reason would be enough for me to go with rebuilding the diesel. If I were buying new, I wouldn't buy the diesel knowing that I would never recoup the additional costs unless I kept the boat for about 65 years.
To me the question is "Does he need the diesels?". If he is only going to run 50 hours a year, it sounds to me like he is a "recreational" fisherman and not "Hardcore". If he is only fishing in the bay or a mile or two offshore, he doesn't need the diesels. If he was going to fish long and hard, then the diesels are the only way to go.... just my 2 cents.....
__________________ Built by Tiara, Powered by Cummins.
1984 31' Open
Well if the entire boat is stripped as it sits now, then there's no difference in the repower, since all wiring and accessories have to be replaced anyway.
In that case, with a boat of this size, I'd say go ahead and do gas.
The problem with diesels is that they require maintenance, the maintenance is not cheap, if you neglect them they go "boom" and the fixes are even more expensive.
Diesels are great - I love 'em myself - but for a boat that is going to be run 50 hours a year and can be reasonably powered with gas you'll never make back the difference in cost.
Find a good used diesel would be the best bet. I would not waste my time rebuilding a engine thats been under for 2 weeks you will find something else wrong at every turn . that said one resone I would not put a lot of money in the boat is will it ever be worth much being it was a salvaged boat ? would you pay full price for a boat (or car)thats been totaled ?could you get insured for any value ?
Another thing to consider is I believe those boats are stern drive. If it is he's going to also have to replace it too, because the gear ratio is setup for a lower rpm diesel not a higher rpm gas engine.
I have been fantasizing about repowereing with diesels for the past two years (and probably will in the next 2). First, I have looked into purchasing these damage boats and have some good friends that are carreer diesel mechanics who emphatically state that once a diesel takes a plung, it's basically only good for the block. The tolerances in diesels are much closer than in gas, so anything that could possibly have corrosion on it MUST be replaced or they will go "Kaboom" very shortly after being installed. The lower end is where all the cost and trouble is. To do it right, you, as a layperson, will spend more money in getting the diesel up to snuff than outright buying a new one. The manufacturer will NOT warranty the rebuild and if you contacted yanmar already and they have the block #'s, its been so noted in their records. Diesel warranties are long and very valuable since the cost to repair them are significant. The manufacturers take them very seriously.
Regarding converting to gas, it might be your best alternative based on your stage of dissassembly, boat size, cost and intended use. Diesel like to run, so 50 hours a year will actually be bad for them. I don't think the difference in weight should come into play, and looking at fuel cost savings is mute in my opinion. Basically the benefits of diesel are 1)increased speed-(higher torque and hp at crusing rpm than a similarly rated gas engine 2)increased range 3)potentially-subject to maintenance-longer service life 4)much less risk of explosion and accordingly lower insurance premiums.
If choosing to put in diesel, you need to be careful that the boat is set up for any other engine other than the yanmar. Yanmar focuses heavily on designing engines for gas (454 & 502 blocks) to diesel conversions where the others (cat, cummins, and detroit - with the new electronic cummings/mercruiser series - the bta replacements?- maybe an exception) do not. Accordingly, your clearances, stringers, water intake and exhaust diameters may be suited for yanmar, but will probably not be suited for the others. (For example, I think you can get away with a 3" exhaust with the yanmar, but the others want 4 - 5"; 1 and 1/2" intake verses 2") Additionally, yanmar requires less of a beefy tranny and smaller shafts since they do not put out as much torque as the other similar sized diesels. (This is to keep the cost of switching from gas to diesel down.)
If you go the gas route, besides making sure that everything on the gas engine is ignition protected, you must also check that everything else in the engine compartment has ignition protected stamped on the labels. This includes battery charger, any relays, water heater, bilge and other pumps/motors, a/c unites, etc. etc. This is probably the case if EVERYTHING installed in the engine room is rated marine, but because of the explosion potential, you MUST verify this. If something is not ignition protected, it will have to be removed and or replaced.
In the end, I think you will end up going gas if saving $$ is a predominate factor.
As far as resale value, the dieseled power boat will sell for higher and in my region (NJ) will be more in demand. I'm not sure of the demand on Lake Erie. As I see it, diesels have come very far in the past few years and more and more people will be wanting them because they have overcome thier largest two obsticles - poorer power to weight ratio than gas and the noise/smoking/odor objection.
You can have the starter rebuilt--same for alternator--or put on an after market alternator. The resale of the boat will be much higher with diesel, plus much less fuel costs. Also no engine mounts rebuild etc. Some parts will be expensive--but not all parts have to come from Yanmar--like bearings...
Doug,
I knew it was a 7 something liter just didn't remember what.
Bob, according to Yanmar the starter and alternator cannot be rebuilt after being under water because of corrosion in the windings. Of course they could be saying that simply to get the order for the new ones.
Help! Rebuild diesel or buy new gas engine. 
