By Bob Links
October 2011
When the time comes to decide whether to rebuild your old engine or replace it with a newer model, there are several factors that should come to mind. The condition and age of the existing engine, overall price of overhaul compared to new, environmental concerns, including working environment and how your engine treats nature, are all things that should be carefully thought about before jumping into a decision half-heartedly.
The condition of your old engine should be your first consideration. Has it been overhauled before? Are parts still readily available for the model engine you have? How much downtime will you have waiting for your engine to be rebuilt? Is there a reliable mechanic available to rebuild your engine?
All of these things can severely and expensively affect your decision to overhaul instead of replace. If your engine has been overhauled before, you need to see if it is even possible to rebuild it again. If during the last rebuild they had to bore the cylinder walls, you may not even be able to rebuild the engine. While some engines have liners in them that can be replaced and brought back to factory tolerance, not all engines have this feature. If your engine is a parent bore engine this means there are no liners. With no liners in the block if a piston ring, piston pin or trash in the cylinder scratches the liner wall, the engine will have to be bored. This will reqire you to completely remove the engine from the boat and strip it all the way down to the block so it can be brought to a machine shop and bored. After this boring is done you will have to decide if you want to use oversized pistons & rings or, if available, install an aftermarket liner. If you go with oversize pistons and rings the engine will no longer be to the original factory specifications and can only be overhauled again if there is enough metal to bore the cylinder again.
Parts availability is another concern that should be carefully analyzed. If you have an older model engine you need to think about how parts availability is, not only right now for your overhaul but how will it be in another 4 or 5 years. It really doesn’t pay to overhaul an old model engine only to find out in 5 years that parts are no longer available for that model. While it is rare for a manufacturer to completely stop building parts for most of their engines they do tend to raise the pricing on the parts as the engines get older.
Pricing is always a consideration when looking at overhauling or replacing your existing engine. While the price of the parts and labor to rebuild your engine is one thing that needs to be compared to the price of a new engine, there are other factors that will affect the price.
Downtime should be considered a pricing question; how much downtime is it going to cost you to rebuild your engine? While most fishermen don’t keep an exact record of the hours they work and how much money they make per hour, their time is still valuable. If you miss a couple of days fishing when the fishing is really good how much will that cost you in lost money? Most overhauls are done in the off-season while there is no fishing. While this is a good idea, you need to also consider how long is the warranty on the overhaul? There are a lot of engine shops that only offer 90-day warranty on repairs or rebuilds. This is usually sufficient if you are running the engine during these 90 days. But if you do the rebuild in the offseason, when does the warranty start? Is your entire warranty gone before you even make your first day of the fishing season?
Most new engines will have at least a two-year/2,000-hour warranty and will cover pretty much all of the parts on the engine. If you rebuild your old engine you will only have warranty on whatever parts were changed or rebuilt. After the rebuild you will still have a block, crank and other parts that are as old as the engine was before you overhauled it.
As was discussed earlier, you also need to look at the parts pricing question. If your engine is a model that has been replaced by a newer model 1 or 2 times since it came out, there is a good chance that the parts prices will start increasing. The older the model the engine and the less of them in the field, the more a manufacturer will have to charge for the replacement parts. This is not because manufacturers are greedy. It is simply because the higher the quantity of a part they sell the less expensive it is to build it. So conversely if they are building fewer of a part the price of that part will be higher.
The last but certainly not the least aspect of price should be to compare the fuel consumption of your old engine to a newer model engine. With the newer technology that most engine manufacturers are using today fuel consumption has really been improved – in some cases by huge amounts. If you have an old heavy engine with older technology, a new engine may pay for itself in only a few fishing seasons. One note to think about when comparing fuel consumption is the weight of the engines. When fuel consumption charts are made the engine is run on a dynamometer. While this gives you accurate HP, torque and fuel consumption readings, you need to remember that when the engine is in your boat it also has to carry its own weight. In other words the heavier the engine is the more fuel you have to burn just to carry it. This weight issue will also limit how much moneymaking load you can carry in the boat. If you carry less paying load you are making less money.
While making money and taking care of your family are the main reasons for fishing, we also want to leave the environment as close to the way we found it. All of the new marine engines available on the market today must meet very stringent EPA standards. Today’s marine engines are cleaner running, quieter and in most cases have very limited vibration. When you begin to compare a new engine to your older technology engine you will find a lot of differences.
Exhaust emissions on the new engines are almost completely invisible today. You don’t see the black smoke coming out of the exhaust like there used to be. This actually has more advantages than helping to keep the air clean. Without all of the soot and black smoke coming out of your exhaust you won’t have to work as hard to keep your boat clean and looking nice. The days of the stack being covered in soot or the transom being black are gone. If your boat looks nice you and your deckhands will not only have a cleaner boat to work on you will just feel better and prouder of your equipment.
Today’s marine engines are also a lot quieter than older engines. Many models can barely be heard running if they are below deck. Combine the quiet running and much less vibration of the newer engines and the overall comfort on the boat is improved drastically. Wouldn’t it be nice to work on the deck without having to yell or feeling like you are standing on a vibrator all day?
One of the newer technologies on today’s marine engines is the electronic engine control. While these controllers were a bit scary to fishermen when they first came out, they do offer several advantages over mechanical controls.
One feature of some of the newer controllers is the ability to track fuel consumption while running. While this doesn’t sound like a big deal, most owners of new engines have found that they can find a spot where they are getting the speed they need but are burning considerably less fuel. They are finding that if they back off the throttle by, say, 100 rpm they may lose less than one knot of speed but save 2-3 gallons of fuel per hour. When you are paying over $3.00 per gallon for diesel this can really add up quickly.
The new controllers also give off a failure code that you can give to your service technician when you call him. This will allow him to know what the problem is before coming to the boat. With this knowledge beforehand he can bring the parts he needs to fix the boat in one trip.
So when you’re considering rebuilding or replacing your existing engine, think about the condition and age of your old engine, the complete pricing issue and how you want your work environment and the world around you to be affected by your decision. ]
Bob Links is the Commercial Marine sales manager for Isuzu Motors America. With nearly 30 years of experience in the marine business and marine engines of all types, he has been with Isuzu for almost 6 years and worked with an Isuzu Distributor for 23 years.